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Conflict detection in 3D MEP coordination : tools, constraints and cost Subramanian, Ganesh 2006

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Conflict Detection in 3D MEP Coordination: Tools, Constraints and Costs by GANESH SUBRAMANIAN B.E (Civil), University of Mumbai, 2002 THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE FACULTY OF GRADUATE STUDIES (Civil Engineering) THE UNIVERSITY OF BRITISH COLUMBIA MARCH 2006 Ganesh Subramanian, 2006 ABSTRACT Coordination is an integral part of many activities during the life of a construction project. Traditionally, building systems are parts of the buildings that temper the building environment, distribute energy, allow for communication, enable critical manufacturing process, and provide and dispose water. With increases in the functionality and complexity of buildings, projects now include much more than just the traditional Mechanical, Electrical, and Plumbing (MEP) systems. The MEP scope now includes additional systems such as fire protection, controls, process piping, and telephone / datacom. Building system coordination involves the detailed layout and configuration of the various building systems such that it complies with design, construction, and operations criteria. Specialty contractors are typically responsible for the coordination of MEP systems, including checking clearances and identifying routes, fabrication details, and installation locations. The current MEP coordination process used in the industry is highly fragmented between design and construction firms, the level of technology used in different coordination scenarios varies significantly and does not provide a facility model for use over the complete life cycle. The main objective of this thesis is elaborate on the role of constraint-based design in MEP coordination process in conjunction with checking for constraint-based conflicts using the state-of-the-art tool, NavisWorks JetStream™ (NavisWorks). To achieve this objective the 3D Models of the MEP Systems of University of British Columbia's (UBC) Chemical and Biological Engineering Building have been analyzed for the constraint-based conflicts and the constraints governing the MEP systems have been classified based on the resulting type of conflict they generate. Also, a quantification of MEP coordination costs sustained in the project and the cost and productivity benefits resulting by implementing 3D MEP coordination for the project have been discussed. The Thesis concludes that using NavisWorks for conflict detection and management does enhance the knowledge on the constraint-based conflicts (e.g. clearance related constraints) in comparison to Autodesk® Building Systems (ABS). The classification of the constraints based on the resulting type of conflicts helps the project participants to have an idea on which constraints have to be given more importance while designing the MEP systems. From the study on the MEP coordination costs and the effect of field generated conflicts on these costs and project ii productivity, this thesis concludes that the investments in coordination typically pay for themselves by reducing conflicts and field generated change order costs in MEP intensive projects. 111 T A B L E OF CONTENTS Abstract. ii Table of Contents. iv List of Tables viii List of Figures x i Acknowledgements x i i Dedication x n Chapter 1: Thesis Overview 1 1.1. Introduction 1 1.2. Literature Review 2 1.2.1. Current MEP coordination processes... 2 1.2.2. Constraint based modeling for various building systems 3 1.2.3. Conflict Resolution Mechanisms 4 1.2.4. State-of-the-art software for constraint-based conflict detection for MEP coordination 4 1.2.5. Cost metrics of MEP design coordination 5 1.3. Research Objectives _ 5 1.4. Methodology 7 1.5. Reader's Guide 8 Chapter 2: MEP Coordination Process: A Review of the Current Practices 10 2.1. Introduction 10 2.2. 2D Design Coordination Process 11 2.2.1. Introduction H 2.2.2. Description 12 2.2.2.1.Sequential Comparison Overlay Process (SCOP) 14 2.2.3. Critique 3 6 2.2.3.1. Benefits 16 2.2.3.2. Limitations 17 2.3. 3D Design Coordination Process.. 20 2.3.1. Introduction 20 2.3.2. Benefits of 3D modeling in MEP coordination process 21 2.4. Conclusion 22 Chapter 3: Literature Review on Constraint-Based Modeling and Conflict Resolution 24 3.1. Constraint-Based Modeling 24 3.1.1. Introduction 24 3.1.2. Related Work 24 3.1.3. Types of Constraints 25 3.2. Conflict Resolution Mechanism 34 3.2.1. Related Work.. 34 3.2.2. Conflict Resolution Strategies ; 37 3.2.2.1 .The Theoretical Approach 37 3.2.2.2.The Practical Approach (Excerpts from other industries) 41 Chapter 4: Review of State-of-the-art Software for Conflict Detection and Management in MEP Systems Coordination 42 4.1. Introduction 42 4.2. Computer Tools 43 4.2.1. Facility Design and Construction 43 4.2.2. Product Design and Manufacturing 46 4.2.3. MEP Coordination Tool..... 46 4.3. Autodesk® Building Systems (ABS) 48 4.3.1. Introduction 48 4.3.2. Conflict Detection Mechanism 48 4.3.2.1.An Overview 48 4.3.2.2.Interference Detection 49 4.3.3. Critique of ABS .' 51 4.3.3.1. Benefits 5 1 4.3.3.2. Limitations 51 4.4. NavisWorks JetStreamTM (NavisWorks) 54 4.4.1. Introduction 54 4.4.2. Introduction to Clash Detection Mechanism 55 4.4.3. Definitions / Terminology ; 56 4.4.4. Clash Batches 58 4.4.4.1.Introduction to Clash Batches 58 4.4.4.2. Managing Batches of Clash Tests 59 4.4.4.3. Merging Clash Tests from multiple files. 59 4.4.4.4.Importing Clash Tests 59 4.4.4.5. Exporting Clash Tests ...60 4.4.4.6. Creating Custom Clash Tests 61 4.4.5. Clash Rules..... 6 2 4.4.5.1.Introduction to Clash Rules 62 4.4.5.2.Setting Clash Rules 63 4.4.5.3. Adding Custom Rules 63 4.4.5.4. Editing Clash Rules 66 4.4.5.5. Deleting Clash Rules 66 4.4.6. Selecting Items for Clash 67 4.4.6.1.An Overview , 67 4.4.6.2.Selecting Items for a Clash Test 67 4.4.6.3.Setting the Clash Test Type and Tolerance Options 68 4.4.6.4.Running the Clash Test 69 4.4.7. Clash Results 69 4.4.7.1. An Overview 69 4.4.7.2. Reviewing Clash Results ...70 4.4.8. Clash Reports ; 71 4.4.8.1. An Overview 71 4.4.8.2. Reporting Clash Results 71 4.4.9. Discussion 72 Chapter 5: Review of UBC Chem Bio Project using Na vis Works 74 5.1. Introduction 74 5.2. Case Background 75 5.2.1. Conflicts Detected by Autodesk® Building Systems (ABS) 77 5.2.2. Classification of Design and Modeling Constraints ...80 5.2.3. Critique...: ...83 5.3. Points of Departure for the Review ...84 5.4. MEP Design and Coordination Constraints 84 5.5. UBC Chem Bio Project Review using NavisWorks 89 5.5.1. Introduction 89 5.5.2. Results for Physical Interferences (Hard Conflict Test) 91 5.5.3. Results for Constraint Based Conflict Detection 100 5.5.3.1. The ducts should maintain a minimum clearance from the adjacent walls and slabs 100 5.5.3.2. Pipes have higher maintenance frequency than ducts; therefore they should not be positioned above the ducts 103 5.5.3.3. The Rain Water Drainage (RWD) Line cannot run below the false ceiling elevation 109 5.5.3.4. The Cable tray has to maintain a 60cm horizontal clearance on one side to provide access to cables 110 5.5.3.5. The Cable tray has to maintain a 30cm vertical clearance on the top side to provide future accessibility to the cables 116 5.5.3.6. The Cable Tray has to maintain a 15cm vertical clearance zone anywhere on the top side 123 5.5.3.7. The required clearance between heating water supply and return lines is 6 in 126 5.5.4. Summary of Results from Constraint-Based Modeling in NavisWorks 127 5.6. Classification of Conflicts 129 5.6.1. Introduction 129 5.6.2. Relation between the types of conflicts and MEP constraints _ 132 5.7. Conclusion 136 vi Chapter 6: Inter-relationship of Conflicts with Project Costs and Productivity 138 6.1. Background 138 6.2. Coordination Efforts vs. Field Conflicts, ____ 140 6.3. Conflict Costs vs. Project Delivery Systems 142 6.4. Design Coordination Costs vs. Project Delivery Systems 143 6.5. Factors Governing MEP Coordination Costs in a Project 145 6.6. Types of Field Conflicts vs. Productivity and Costs due to Field Conflicts . 147 6.7. MEP Coordination Cost for UBC Chem Bio Project . 151 6.7.1. Computation of Actual MEP Coordination Cost 151 6.7.2. Computation of Predicted Coordination Costs _ 154 6.8. Conclusion 156 Chapter 7: Conclusions and Recommendation for Future Work 158 7.1. Conclusion 158 7.2. Recommendation for Future Work 159 References 160 vii LIST OF TABLES Table 1.1: Priority Order SCOP 16 Table 3.1: The Codes and Standards governing the design M-E :P Systems 27 Table 3.2: The design and construction constraints identified in the case study, classified according to the knowledge domain, knowledge attributes, and modeling and coordination tasks 31 Table 3.3: Constraints in Mechanical Desktop 33 Table 3.4: The defining constraint operations 34 Table 3.5: Coordination of active systems 41 Table 4.1: Commercial tools for detailed design/simulation task 44 Table 4.2: Commercial tools for configurational task 45 Table 4.3: Commercial tools for both detailed design/simulation and configurational tasks 45 Table 5.1: Classification of Constraints based on Knowledge Domain, Attribute, Modeling & Coordination Tasks 82 Table 5.2: Final List of Design and Modeling Constraints Governing MEP Systems...85 Table 5.3: Summary of Clashes Detected using NavisWorks with respect to type of system 128 Table 5.4: Type and Description of Interferences Identified by Tatum and Korman (2001) 130 Table 5.5: Types of Coordination Conflicts, Timing of Detection, and Severity of Impact 130 Table 5.6: Classification of Interferences identified by Tabesh and Staub-French in their study (2005) :133 Table 5.7: Classification of Constraints with respect to the Type of Interference(s) they result in 135 Table 5.8: Classification of Constraints based on Knowledge Domain, Attribute, Modeling & Coordination Task and Resulting Type of Interference 137 Table 6.1: MEP Systems as a percentage of Total Building Cost 138 Table 6.2: Types of Coordination Conflicts, Timing of Detection, and Severity of Impact 150 Table 6.3: Computation of Actual Coordination Cost for UBC Chem Bio Project...... 153 viii Table 6.4: Computation of Predicted MEP Coordination Costs for UBC Chem Bio Project 155 Table 6.5: Summary of MEP Coordination Costs for UBC Chem Bio Project 157 LIST OF FIGURES Figure 1.1: Design disciplines and construction trades involved in M E P coordination. 12 Figure 1.2: Current practice using light table (SCOP) 14 Figure 1.3: Sequence for the Comparison Overlay Process . _ 15 Figure 3.1: The three dimensions of the M E P Knowledge Framework __ 30 Figure 3.2: Example of Constraint 32 Figure 4.1: Highlighting an interference condition 49 Figure 4.2: Options Window of ABS ; 50 Figure 4.3: Post rendered image in ABS after running collision detection tool 52 Figure 4.4: A Typical Unreported Conflict in ABS 53 Figure 4.5: Batch Window in NavisWorks... 58 Figure 4.6: Import Dialog Box in NavisWorks.. 60 Figure 4.7: Export Dialog Box in NavisWorks 61 Figure 4.8: Rules Window in NavisWorks 62 Figure 4.9: Rules Editor Window in NavisWorks 64 Figure 4.10: Select Window in NavisWorks 67 Figure 4.11: Results Window in NavisWorks 69 Figure 4.12: Report Window in NavisWorks 71 Figure 5.1: 3D Model of Chemical and Biological Engineering Building Project 76 Figure 5.2: Integrated 3D model of a typical lab on the fifth floor 71 Figure 5.3: The three dimensions of the framework used to classify the design and construction knowledge 81 Figure 5.4: Typical Approved Clash for Fifth Floor Level for Physical Interference Test 92 Figure 5.5: A Typical Active Clash for Fifth Floor Level for Physical Interference Test ...93 Figure 5.6: A Typical Approved Clash for Sixth Floor Level for Physical Interference Test 94 Figure 5.7: A Typical Active Clash for Sixth Floor Level for Physical Interference Test..95 Figure 5.8: A Typical Approved Clash for Main Floor Corridor Area for Physical Interference Test 96 Figure 5.9: A Typical Active Clash for Main Floor Corridor Area for Physical Interference Test 97 Figure 5.10: A Typical Approved Clash for Second Floor Corridor Area for Physical Interference Test 98 Figure 5.11: A Typical Active Clash for Second Floor Area Corridor for Physical Interference Test 99 Figure 5.12: A Typical Approved Clash for Fifth Floor Area for 5.5.3.1 101 Figure 5.13: A Typical Approved Clash for Main Floor Corridor Area for 5.5.3.1_ 102 Figure.5.14: A Typical Active Clash for Main Floor Corridor Area 5.5.3.1 103 Figure 5.15: A Typical Approved Clash for Fifth Floor Level for 5.5.3.2 105 Figure 5.16: A Typical Active Clash for Fifth Floor Level for 5.5.3.2 106 Figure 5.17: A Typical Approved Clash for Sixth Floor Level for 5.5.3.2......... 107 Figure 5.18: A Typical Approved Clash for Main Floor Corridor for 5.5.3.2 108 Figure 5.19: A Typical Active Clash for Main Floor Corridor Area for 5.5.3.2 109 Figure 5.20: A Typical Approved Clash for Sixth Floor Level for 5.5.3.4 111 Figure 5.21: A Typical Approved Clash for Second Floor Corridor Area for 5.5.3.4 112 Figure 5.22: A Typical Active Clash for Second Floor Corridor Area for 5.5.3.4 113 Figure 5.23: Active Physical Clash between Electrical Ceiling Device and Cable Tray in Second Floor Corridor Area 114 Figure 5.24: A Typical Approved Clash for Main Floor Corridor Area for 5.5.3.4_ 115 Figure 5.25: A Typical Active Clash for Main Floor Corridor Area for 5.5.3.4 116 Figure 5.26: A Typical Approved Clash for Sixth Floor Level for 5.5.3.5 117 Figure 5.27: A Typical Active Clash for Sixth Floor Level for 5.5.3.5 118 Figure 5.28: A Typical Approved Clash for Second Floor Corridor Area for 5.5.3.5 119 Figure 5.29: A Typical Active Clash for Second Floor Corridor Area for 5.5.3.5 120 Figure 5.30: A Typical Approved Clash for Main Floor Corridor Area for 5.5.3.5 121 Figure 5.31: A Typical Active Clash for Main Floor Corridor Area for 5.5.3.5 122 Figure 5.32: A Typical Approved Clash for Sixth Floor Level for 5.5.3.6 123 Figure 5.33: A Typical Active Clash for Sixth Floor Level for 5.5.3.6 124 Figure 5.34: A Typical Active Clash for Second Floor Corridor Area for 5.5.3.6 125 Figure 5.35: A Typical Active Clash for Main Floor Corridor Area for 5.5.3.6 126 Figure 6.1: Coordination Effort vs. Number of Conflicts 141 Figure 6.2: Project Delivery System vs. Conflict Costs 143 Figure 6.3: Type of Delivery System vs. Coordination Costs 144 Figure 6.4: Effects of Field Conflicts 148 Figure 6.5: Type of Field Conflict vs. Resulting Cost (Change Order) 149 ACKNOWLEDGEMENTS The work that is the basis for this thesis has been carried out from the summer of 2005, to the spring of 2006, at the Civil Engineering Department in University of British Columbia. It has been a challenging period of my life, and the completion of this work would have never been possible without the support of many people that have contributed to the development of this thesis, as well as to my own development as an individual. First, I would like to thank my supervisor and mentor, Dr. Sheryl Staub-French and express my sincere gratitude for her continuous support, invaluable guidance, and constructive criticism over this study in the past one year. I appreciate her patience and dedication without which this work would not have been possible. In addition, I would like to thank Dr. Thomas Froese for his constructive criticism, and sage advice. I would also like to thank my colleagues and friends at the Civil Engineering Department for their support and companionship. In particular, I would like to thank Mr. Abdorreza Tabesh for the insight he gave me into this research topic at the start of my work. A special thanks goes to my friends Chand Kumar, Navdeep Gupta, Mithun Shetty and P.V.S.N. Murthy for their friendship and support throughout this process. Finally, I am most grateful to my family and my fiancee for their tremendous encouragement and support throughout my life, and particularly throughout my time at UBC. xn DEDICATION To my Grandparents, Parents & my fiance, Ankhi Chapter 1: Thesis Overview 1.1. Introduction Coordination is an integral part of many activities during the life of a construction project. Traditionally, building systems are parts of the buildings that temper the building environment, distribute energy, allow for communication, enable critical manufacturing process, and provide and dispose water. Architects and engineers also refer to the building systems as the active systems of the building. With increases in the functionality and complexity of buildings, projects now include much more than just the traditional Mechanical, Electrical, and Plumbing (MEP) systems. The MEP scope now includes additional systems such as fire protection, controls, process piping, and telephone / datacom. In a complex building project, coordination of MEP systems is a critical and challenging task. Building system coordination involves the detailed layout and configuration of the various building systems such that it complies with design, construction, and operations criteria (Barton, 1983; Tatum and Korman, 2000). Specialty contractors are typically responsible for the coordination of MEP systems, including checking clearances and identifying routes, fabrication details, and installation locations (Korman and Tatum, 2001). Many construction industry professionals have cited M E P coordination as one of the most challenging tasks encountered in the delivery process for construction projects. There are three primary reasons for this. First, the process is highly fragmented between design and construction firms. Second, the level of technology used in different coordination scenarios varies significantly. Third, the current manual process does not provide a facility model for use over the complete life cycle (Korman and Tatum, 2001). This thesis essentially builds on the work done by Tatum and Korman (2001), Tabesh and Staub-French (2005) and Riley et al (2005). The main focus of this thesis is the case study on the University of British Columbia's (UBC) Chemical and Biological Engineering Building by Tabesh and Staub-French. This facility provides a variety of teaching and research spaces for the study of biological, chemical, environmental and process engineering at UBC. In this thesis, the 3D Models of the M E P Systems created by Tabesh and Staub-French (2005) have been analyzed for the constraint-based conflicts using more sophisticated conflict detection and management tool than Autodesk® Building Systems (ABS), NavisWorks Je tStream™ (NavisWorks). 1 The additional conflicts identified in this study have been classified with respect to the conflict classification framework designed by Tatum and Korman (2001) and Riley et al. (2005). In addition to this, a relationship between the constraints governing the MEP systems and the resulting type of conflict they generate is also given. As the study by Tabesh and Staub-French was one of the firsts to use 3D modeling technique for MEP coordination process, it was necessary to quantify the coordination costs and understand what the cost and productivity benefits in the project were. This thesis uses the cost benefits metrics designed by Riley et al. (2005) for quantifying the coordination costs incurred in the UBC Chem Bio Project. The main contributions of this research are the evaluation of the state-of-the-art software for 3D MEP coordination process, the relationship between the various governing constraints and the type of conflicts they generate and the cost benefits resulting from doing an early and high level of coordination effort for a project. This chapter gives an overview on the literature review, the research objectives, and the research methodology of this study. 1.2. Literature Review For this research, I reviewed the literature in the following areas: • Current MEP coordination processes (2D and 3D coordination processes) • Constraint based modeling for various building systems • Conflict Resolution Mechanisms • State-of-the-art software for constraint-based conflict detection for MEP coordination • Cost metrics of MEP design coordination, and the relationships between coordination efforts, types of project delivery systems, and field interference problems. 1.2.1. Current M E P coordination processes Tatum and Korman (2001) defined MEP coordination as "the arrangement of components of various building systems within the constraints of architecture and structure." Tatum and Korman (2000) conducted a study on the MEP coordination process. They identified MEP coordination knowledge that was relevant to design, construction, and operations and 2 maintenance. They investigated the 2D coordination process and suggested the need for a revised work process based on a 3D model. They also emphasized the need for full visualization capabilities as a requirement of effective MEP coordination, which allows sections cut at any point and direction. They also suggested the use of a composite 3D CAD model that combines preliminary designs for each system. Further research was conducted to develop a framework to represent MEP coordination knowledge in a computer tool (Korman et al. 2003). Tabesh and Staub-French (2005) built on these needs defined by the past research and used 3D modeling and collaboration of the MEP systems for MEP coordination process in their study on UBC Chem Bio Project and highlighted the benefits resulting from the use of 3D models in design coordination and these have been discussed in more detail in Chapter 2 of this thesis. 1.2.2. Constraint-based modeling for various building systems All the projects in the world are governed by certain constraints (e.g.: time, cost, design) laid out in the project. For a project to be a successful the project participants have to do a balancing act between all the constraints involved in the project and it's the balance that they achieve which makes the project viable and successful and beneficial to all the project participants. It is the knowledge of the design constraints that guides the designer to find a solution. Nassar et.al (2003) introduced in their study, the use of constraint-based assembly operations to help the designer in the generation of building assembly details and overcoming the need to recreate the detail for each new design. Constraint-based assembly operations are essentially a set of constructive operations that act on components of the assembly to place them in the correct position within the assembly. They also identified the types of constraints that one comes across in the real world while designing a project such as mathematical constraints, design and modeling constraints, constraints resulting from governing codes and standards, geometrical constraints and declarative constraints. They also gave an example of how these constraints govern the design in the mechanical industry and these have been discussed in more detail in Chapter 3 of this thesis. 3 1.2.3. Conflict Resolution Mechanisms Conflict resolution is the process that takes place simultaneously while one does the constraint-based design of the components. Mark Klien (1990) in his study on conflict resolution proposed a model of run-time conflict resolution in cooperative design that had advantages over existing conflict resolution approaches. This model was designed keeping in mind the mechanical engineering industry, however we as civil engineers can adopt some aspects of the model for MEP Coordination Process as MEP Coordination is also a cooperative design. It is based on the notions that conflict resolution expertise can be captured explicitly, and in addition can be organized usefully into taxonomy of conflict classes and associated conflict resolution strategies. He also divided the computational models of conflict resolution into different categories and gave developed a comprehensive theoretical approach on conflict resolution strategies based on these categories. While reviewing the literature on theoretical conflict resolutions strategies, I also reviewed the computer models, the product design and manufacturing industry uses for its coordination process and these have been discussed in more detail in the Chapter 3 of this thesis. 1.2.4. State-of-the-art software for constraint-based conflict detection for MEP coordination During the early and mid-1980s, CAD was gaining ground and becoming an efficient alternative to the drafting table. With the increased use of CAD, architects were continuously devising ways to automate drafting and design tasks in order to increase their efficiency. In recent years, 3D CAD models have become more popular in the design and construction industry. These tools are able to produce a complete product model, which assists in the configurational design task. These tools allow for faster design in detail, as they contain libraries of components stored in databases for use in building a specific plant model. Many of the tools have the ability to detect both physical interferences and clearance violations. Autodesk® Building System (ABS) is one such tool which is currently used by many in the industry for 3D modeling and conflict detection for the MEP Coordination process. The limitations of ABS as a comprehensive conflict detection and management tool in the industry 4 prompted me to review another state-of-the-art software tool, NavisWorks Clash Detective (NavisWorks). NavisWorks has the capability to act as a comprehensive conflict detection and management tool and has many advantages over ABS. The general outline on the working of ABS and NavisWorks has been discussed in the Chapter 4 and the use of NavisWorks for determining constraint based conflicts for the UBC Chem Bio Project has been discussed in Chapter 5 of this thesis. 1.2.5. Cost metrics of M E P design coordination While reviewing the past research in the MEP Coordination, I found that the past studies had not elaborated many details on coordination costs for doing a MEP coordination process and also what impacts do the conflicts arising during coordination have on the project costs and productivity. Riley and Horman (2001) presented a pre-study of the cost metrics of design coordination, and the relationships between coordination efforts, types of project delivery systems, and field interference problems and designed predictive coordination cost models for the MEP coordination process. I have built on the predictive models for coordination costs that were designed by Riley et al. (2005) and computed the cost benefits and variance in the coordination costs for the UBC Chem Bio Project to outline what cost and productivity benefits one gets in the project by using a 3D design and collaboration process for MEP coordination, which is discussed Chapter 6 of this thesis. 1.3. Research Objectives The research objectives of this study were: • Understand the role of constraint-based design in MEP coordination process in conjunction with checking for constraint-based conflicts in the UBC Chem Bio Project using robust conflict detection tool, in this case NavisWorks Clash Detective. I started off with looking into the literature on constraint-based modeling and conflict resolution mechanisms in various industries such as mechanical and manufacturing industry (Chapter 3). Building on the ideas of this literature and the past research in the field of MEP coordination (Chapter 2), I looked into the constraints governing the MEP 5 coordination process and did a constraint-based conflict analysis in NavisWorks using the UBC Chem Bio Project as my example (Chapter 5). This includes checking for physical conflicts and also constraint-based analysis for conflicts (e.g.: clearance based constraints for MEP Systems). • Compare the results of conflicts identified from NavisWorks for the UBC Chem Bio Project with the previous study by Tabesh and Staub-French (2005) on the UBC Chem Bio Project wherein they had used ABS for conflict detection of MEP systems. Although Tabesh and Staub-French had identified 50 physical interferences in the MEP systems of UBC Chem Bio Project, they had missed around 106 conflicts resulting just from the physical interference test of the 3D models of the UBC Chem Bio Project (Section 5.5.2). In addition to this I did a constraint-based analysis for the conflicts generated from the clearance constraints for the MEP systems and this analysis yielded an additional 69 active conflicts in the 3D Models of the UBC Chem Bio Project (Section 5.5.3). This analysis on the 3D models helped me in strengthen the conclusion that NavisWorks is a far better conflict detection and management tool than ABS. • Classify the conflicts identified in UBC Chem Bio Project with respect to the type they represent using Korman's Classification Framework (2001) Le. actual, extended, future, temporal and functional types of conflicts. Tabesh and Staub-French (2005) documented the conflicts in their study but they did not classify them based on Korman's or Riley et al.'s (2005) classification frameworks. For the conflicts they identified in their study, the classification based on Korman's classification framework is discussed in Section 5.6 of this thesis. • Classify the constraints that govern the MEP Coordination Process with the types of conflicts they generate in conjunction with the classification of the constraints by Tabesh and Staub-French (2005). Past research in this area just collected the knowledge with regards to the various constraints governing the MEP systems in a project (Section 5.2.2 and 5.4). Tabesh and Staub-French (2005) classified the knowledge they collected in their study on UBC Chem Bio Project based on the knowledge domain, the domain context, and the specific modeling and coordination task identified for the MEP coordination process by Tatum and Korman (2001). In this study, from the results of constraint-based analysis of the UBC Chem Bio Project in NavisWorks, I have classified these MEP constraints based on the type of conflicts they generate or can generate in a project (Section 5.6). 6 • Establish a relationship between the MEP Coordination Process and Coordination Costs and highlight the cost and productivity benefits one attains by doing an early and high level of coordination in a project using UBC Chem Bio Project. Riley and Horman (2001) presented a pre-study of the cost metrics of design coordination, and the relationships between coordination efforts, types of project delivery systems, and field interference problems and designed predictive coordination cost models for the MEP coordination process. I used these cost metrics and predictive models designed by Riley to compute variance of the actual coordination against these predictive models for UBC Chem Bio Project and using the number of conflicts identified in my study and Tabesh and Staub-French's (2005) study on UBC Chem Bio Project, I have computed the cost and productivity benefits resulted in this project (Section 6.7). 1.4. Methodology The methods used to achieve the research objectives include the following: • Literature Review: I reviewed the available literature in the area of MEP coordination to identify the body of knowledge which I could use and build upon in this study. In addition, the literature review helped me to identify what was missing in these studies and how my research could contribute to this body of knowledge. This formed a solid background for performing the case study, as well as the point of departure for my research. I also reviewed the literature of classification schemes and knowledge frameworks in the construction domain which helped to establish the basis for my data analysis and classification. • Review State-of-the-art 3D Software for conflict detection and management: Throughout the first couple of weeks of my study, I learned and worked with ABS, which is the state-of-the-art software used by many in the industry. This gave me a better understanding on the benefits of this tool and its limitations. In the second phase of my evaluation, I learned and worked with NavisWorks which appeared to be a more robust and sophisticated tool than ABS. In order to give my full critique on the ability this tool, it was necessary to review a case study and then compare these two software tools. As Tabesh and Staub-French had used ABS in their study on UBC Chem Bio Project for conflict detection, I used the same project as my example for reviewing the ability of NavisWorks as a more comprehensive conflict detection and management tool. 7 • Constraint Based Conflict Detection in NavisWorks: I reviewed the 3D models for the MEP systems built by Tabesh and Staub-French (2005) for the UBC Chem Bio Project. Using NavisWorks, I checked the floor areas (Fifth Floor, Sixth Floor, Main Floor Corridor and Second Floor Corridor) for which Tabesh and Staub-French had developed 3D Models for the physical interferences and, as NavisWorks has the ability to check for constraint based conflicts, I reviewed these floor areas for the conflicts resulting from these constraints (clearance-based constraints). • Knowledge Classification: I classified the collected knowledge (conflicts from my analysis of the UBC Chem Bio Project in NavisWorks and constraints from past studies in the field of MEP coordination) by building on and extending existing knowledge frameworks found in the literature. My goal was to establish the relationship between the various governing constraints and the type of conflicts they result in. • Evaluate MEP Coordination Cost: In addition to this, I also built on the cost metrics designed by Riley et al. (2001, 2005) and computed the variance in coordination costs of MEP coordination process and evaluated the cost and productivity benefits the use of 3D design and collaboration resulted in the UBC Chem Bio Project. 1.5. Reader's Guide I have started off this thesis by looking into the current 2D and 3D MEP coordination processes and analyzing the pros and cons of the same and I have concluded that the use of 3D design and collaboration process for MEP coordination is more advantageous then the 2D paper based coordination process. In the next chapter I have looked into the literature on the constraint-based modeling and conflict resolution mechanisms from the other industries such as Mechanical and Manufacturing industries. This helped me gain several insights into a cooperative design collaboration process and what are the various theoretical approaches one can take for resolving conflicts in the design. In the next chapter, I have reviewed the pros and cons of the two widely used tools for conflict detection and management in the construction industry for MEP coordination process viz; Autodesk® Building Systems (ABS) and NavisWorks JetStream™ (NavisWorks) and I have concluded that NavisWorks is a better conflict detection and management tool than ABS as one can also do a constraint-based conflict detection in addition to the physical interference tests for the 3D models of the MEP systems. In order to strengthen my conclusion on NavisWorks, I reviewed the MEP system of UBC Chem Bio Project using 8 NavisWorks for physical and constraint-based conflicts in the next chapter. My analysis yielded an additional 106 physical interferences and 69 constraint-based conflicts from the original 50 identified by Tabesh and Staub-French (2005) in their study on UBC Chem Bio Project using ABS. In the concluding section of my review on UBC Chem Bio Project, I have classified the various MEP constraints with respect to the types of conflicts they generate based on Korman's (2001) classification framework. In the last chapter of this thesis, I have computed the MEP coordination costs for the UBC Chem Bio Project and also evaluated the cost benefits achieved in this project (approximately $15.51 Million) by using 3D modeling technique for design and collaboration of MEP coordination process. 9 Chapter 2: M-E-P Coordination Process: A Review of the Current Practices 2.1. Introduction Coordination is an integral part of many activities during the life of a construction project. Traditionally, building systems are parts of the buildings that temper the building environment, distribute energy, allow for communication, enable critical manufacturing process, and provide and dispose of water. Architects and engineers also refer to the building systems as the active systems of the building. Design and construction professionals use the acronym MEP systems, which stands for mechanical, electrical, and plumbing systems. With increases in the functionality and complexity of buildings, projects now include much more than just the traditional mechanical, electrical, and plumbing systems. The MEP scope now includes additional systems such as fire protection, controls, process piping, and telephone / datacom. Although many of these systems may seem similar in nature, different specialty contractors often install them. In fact, the entire construction process requires coordinating key resources such as information, material, equipment, and labor. Tatum and Korman (2001) in their study stated that Mechanical, Electrical, and Plumbing (MEP) Coordination is the arrangement of components for various active building systems, which are critical to a building's function and must meet performance expectations for comfort and safety. These building system components must also fit within the constraints of architecture and structure. Coordination is a process that involves defining the locations for components of these building systems; often in congested spaces, in order to avoid interferences and to comply with diverse design and operations criteria. Ideally, the result of such a coordination effort is the most economical arrangement that meets critical design criteria and performance specifications. The level of difficulty associated with this process directly relates to the complexity and number of building systems in a facility, which in recent years has increased. Many coordination activities relate to MEP systems. A few are as follows: • Integration of MEP systems into the architectural and structural envelope • Integration of detailed MEP trade drawings • Creation of equipment matrices and selection of suppliers • Installation and procurement scheduling for MEP systems • Acquisition of supplier drawings for components of MEP systems 10 • Tracking and formalizing procedures for submittals • General contractor's management of MEP specialty contractors. Many construction industry professionals have cited MEP coordination as one of the most challenging tasks encountered in the delivery process for construction projects. There are three primary reasons for this. First, the process is highly fragmented between design and construction firms. Second, the level of technology used in different coordination scenarios varies significantly. Third, the current manual process does not provide a facility model for use over the complete life cycle. (Tatum and Korman, 2001) 2.2. 2D Design Coordination Process 2.2.1. Introduction In the detailed study on MEP Coordination Process, Tatum and Korman (2001) observed various projects that incorporated this coordination and stated that coordination of mechanical, electrical, and plumbing (MEP) systems is a major challenge for complex buildings and light manufacturing plants. M E P coordination is required to establish the detailed location and configuration of the H V A C , electrical, process, plumbing, fire protection, and other systems. Many aspects of current projects constrain this activity: limited building space, increasing complexity of all building systems, and limited engineering budgets and installation schedules for MEP systems. Combined with increasing pressures for better, faster, and cheaper projects, these constraints highlight the need for an improved work process for MEP coordination. Technical specifications for building projects typically assign responsibility for M E P coordination to the specialty or trade contractors. This includes checking for clearances, field conditions, and architectural conditions. The process of M E P coordination involves locating components and branches from all systems in compliance with design, construction, and operations criteria. MEP coordination meetings may include the project engineer from the general contractor, the project manager from the engineering firm, and an engineer or detailer from each of the specialty contractors. 11 2.2.2. Description The 2D Work process for MEP coordination begins with design consultants, or design build contractors who perform design, designing their systems independently. They generally prepare diagrammatic drawings indicating the required equipment and a path for the connecting elements of their system. Once engineers complete the system designs, the coordination process begins with meetings involving each of the specialty contractors (e.g., Heating Ventilation and Air Conditioning (HVAC) ductwork and piping, process piping, plumbing, electrical, fire protection, controls). These specialty contractors eventually fabricate and install these systems. (See Figure 1.1.) Figure 1.1 - Design disciplines and construction trades involved in M E P coordination (Source: Tatum and Korman, 2001) The MEP coordination process is usually outlined by general contractors in their contract documents. The team leader is often the heating, ventilation, and air conditioning (HVAC) contractor who designs large duct and piping layouts on the architectural background. Other systems are then added to this scale drawing. Ideally, the coordination process uses a computer aided design (CAD) platform to detect and resolve interferences between systems. However, in many cases, a subcontractor's time and .CAD resources are constrained, and coordination is conducted by the more conventional process of overlaying scaled transparent drawings on a light table and comparing them sequentially. In some cases, the process is not carried out at all. 12 MEP coordination begins after design and preliminary routing of all building systems (mechanical, plumbing, electrical, etc.). The design is complete when engineers have sized all components (e.g., conduits, pipe, and HVAC duct), completed the engineering calculations, and produced the diagrammatic drawings; however, engineers have not defined specific routing. Usually, they size HVAC and piping systems during this initial design. Other trades, such as electrical and fire protection, do not. Therefore, they draw some of the systems to scale and others simply as lines with references to component sizes. The design consultants typically assign full responsibility for coordination to the specialty contractors, including checking for clearances, field conditions, and architectural conditions. Representatives from each of the specialty contractors (primarily HVAC wet and dry, plumbing, electrical, and fire protection) meet to discuss their particular designs and drawings, which indicate the proposed routing for each system to follow to service each required location. Common constraints for them to consider in routing MEP systems are corridors, openings in shear walls, and architectural requirements, such as ceiling type and interstitial space. The architect and structural engineer set the envelope for routing MEP systems. The preliminary routing drawings reflect these constraints; each trade routes their system to their own advantage. This includes decreasing overall length, routing close to support points, choosing prime locations for major components, and locating system runs to facilitate the construction needs of their own trade. In the coordination meetings, Tatum and Korman (2001) observed that the participating specialty contractors compare preliminary routing for their systems to identify and resolve conflicts. The MEP trades use a Sequential Comparison Overlay Process (SCOP) to overlay their design drawings. SCOP continues until they resolve all interferences. This often requires preparing section views for highly congested areas to identify interferences. They also decide which contractor(s) will revise their design and submit requests for information regarding problems that require an engineering resolution. The product of this process is a set of coordinated shop drawings that the specialty contractors submit to the design engineer for approval. Upon completion of SCOP, all specialty contractors involved (mechanical, electrical, plumbing, and fire protection) sign-off on each others' drawings, indicating that they accept the coordinated design for the specific area of the facility. Specialty contractors then prepare cut sheets for duct fabrication and spool sheets for piping, based on the coordinated shop drawings. They fabricate 13 duct and larger pipe in shops and ship the pieces to the site. The contractors' crews install the systems, using the shop drawings to define location. Quality control personnel generally inspect the system using the diagrammatic drawings from the engineer. To complete the system, the contractors prepare as-built or record drawings by marking and editing the shop drawings or by consolidating electronic files. 2.2.2.1. Sequential Overlay Compar ison Process ( S C O P ) This process starts with the design of the system by designers, architects, and engineers. The design consultant assigns responsibility to the trade contractors to check for clearances, field conditions, and architectural constraints. Each trade generates shop drawings to its own advantage, choosing prime locations for their components, and locating runs to facilitate their own trade requirements. Representatives from each trade meet and indicate the proposed routing and location of their systems. Scale transparent drawings for each trade are overlapped on a light table, so that conflicts are apparent. EagiraermE Diawiagsl (diagraminauc) Shop drawiap (by Trade) Detailed stop diawinfs S'or fabsicasioa aid lastallatioa (Specialty C«mractors) Review Coordinated shop drawiajs (EapieaiBE and Oroer) Siga-otf Meetusg (Genera! Contracsors & Soeclaltv Cwuranon Fataicatioa, IcstaHanon. Record Drewinss Figure 1.2 - Current practice using light table (SCOP) (Tatum and Korman, 2001) 14 The trade representatives then work together and reroute the systems and revise the drawings for optimal location and placement. In cases of major redesign, design engineers are asked for additional information and ultimately sign off and accept responsibility for design changes. This process is repeated and the product is a set of coordinated drawings, which they submit to the design engineer for approval. Next, shop drawings and cut sheets are generated for fabrication and the contractor's crews use the coordinated shop drawings for field installation. To complete the process, as-built drawings are prepared by marking or editing the shop drawings. Figure 1.3 gives the sequence of the comparison overlay process and Table 1.1 summarizes the priority order for the Sequential Overlay Process. Electrical 5 Fire Protection 4 Plunibiiie: H V A C Wet H V A C Dry 1 3 Figure 1.3: Sequence for the Comparison Overlay Process (Tatum and Korman, 2001) 15 System Priority / Special Notes Mechanical (HVAC Dry) Usually first due to large size of Components Mechanical (HVAC Wet) Follows HVAC Dry due to interdependence of these systems Plumbing (gravity driven systems) Design criteria for slope essential for System performance Process piping Takes first priority if critical to manufacturing process Fire Protection Most flexible routing, especially small diameter pipe Plumbing (pressure driven systems) Lower priority because less difficult to re-route Electrical Flexible routing within safety and architectural requirements Control systems Flexible routing but must limit bend Radius for pneumatic tubes Telephone/Data communications Flexible routing but must limit bend Radius for fiber optic cables Table 1.1: Priority Order SCOP (Tatum and Korman, 2001) 2.2.3. Critique of the Current Practice 2.2.3.1. Benefits • It provides opportunity to value-engineer the entire project. • It allows interaction of representatives from many disciplines and construction trades to gather and discuss configuration alternatives i.e. interaction of consultants and sub trades from the various fields of the industry. • It promotes sharing knowledge regarding the multiple systems i.e. by group interaction of the various MEP Project Participants, there happens a knowledge sharing among them and thus they update their knowledge to the current of the individual participants. • It allows for the identification of many problems prior to field work, but it is not thorough enough to detect all conflicts. • It instigates discussion of construction scheduling and installation sequencing, but does not allow for a detailed investigation. 16 2.2.3.2. Limitations • The coordination process is slow and expensive. MEP coordination often delays the project and increases the cost for all involved in the process (Hanna, 1999). • Coordination is often not budgeted in the construction cost Le. it is a hidden cost in the design category. The sequential and iterative process is very slow because specialty contractors make only slight progress at each meeting and also involves the project participants from the MEP Systems (Sub Trades, Consultants, Project Manager Etc.). An example of this is the coordination of the MEP systems for labs on the basement floor of the McCullough Annex building on the Stanford University campus. The 57,000-sf basement required 15 meetings and 520 person hours for an estimated coordination cost of $260,000. This estimate includes time spent by personnel inside and outside coordination meetings as well as travel time to meetings. (Tatum and Korman, 2001) • The coordination process is also highly fragmented. Design and coordination take place on an as-needed basis (Tatum and Korman, 1999). Engineers and contractors do not perform design and coordination sequentially. There is a lack of knowledge and understanding regarding the multiple disciplines involved, which often gives rise to systems that needs redesign to meet coordination criteria. In many instances, parts of the systems must be re-coordinated in different stages. • It is difficult to integrate construction knowledge into the MEP coordination process. Often the parties involved do not take the opportunity to align goals and define requirements. In addition, the MEP design consultants' do not consider constructability issues, and designers must make assumptions about constructability or ignore the issue totally. Furthermore, there is a lack of understanding between the different MEP trades. Each discipline focuses on its own design and construction requirements. Failing to consider the big picture, many MEP contractors are unaware of unique installation requirements for other trades and are reluctant to learn more about or consider each other's systems. • Because of the lack of communication between designers, builders, and operations personnel, it is difficult to integrate knowledge about operation and maintenance of the facility. Operations and maintenance personnel often are not involved in coordination decisions; therefore, designers must make assumptions concerning the user's needs. • Three-dimensional space requirements are difficult to visualize. Contractors performing coordination with two-dimensional flat drawings overlaid on each other face the problem 17 in interference-checking as the visualization they can do in 2D is limited while most of the components installed are required to be visualized in 3D. Specialty contractors need many section views and they manually calculate clearances since they perform the procedure with flat drawings. When specialty contractors produce drawings on computer-aided-design (CAD), they can use a number of software systems products such as QuickPEN™ or AutoCAD's SoftDESK™ for interference checking. Even with the aid of CAD software, specialty contractors may still need to produce cross-section and projection views to visualize congested spaces. In some extreme cases, specialty contractors construct full-scale mock-ups of very congested areas to identify places of conflict in order to alleviate concerns regarding constructability, operations, and maintenance. The level of technology used in difficult coordination scenarios varies. Specialty contractors use a wide range of technology to assist with MEP coordination. Plant design systems, which some engineering and construction firms use on large process and power plants, can avoid many of the problems associated with MEP coordination (Tatum and Korman, 1999). However, these large projects usually require large computer systems to handle the design on 3D CAD platforms. Specialty contractors, who design, fabricate, and construct the project, perform the MEP coordination on most projects. These specialty contractors usually do not possess the sophisticated computer systems or technical knowledge to take advantage of 3D CAD's capabilities. Instead, they work independently of others, using 2D CAD platforms. In rare cases, a specialty contractor will use a 3D CAD platform for design; however, these are usually very special systems and data are not transferable or compatible with other systems. Upon the completion of the current coordination process, no electronic models of the facility remain with the owner for use over the facility's life cycle. Facility managers and maintenance personnel use as-built drawings provided by the contractor. Furthermore, the coordination process often must take place in two stages, once for the coordination of the building systems under the core-and-shell construction contract and again under the construction contract for tenant improvement. Facility managers must prepare as-built drawings of core-and-shell construction in order to provide information for tenant improvement contracts. In the current practice, many of the identified issues in this research are resolved on site by the specialty trades. This is usually done under pressure of a tight schedule, and 18 therefore, the resulting solutions are not always the best solutions. In addition, in a number of these situations, the knowledge utilized remains implicit and is not documented. By revealing and exposing the issues sooner in the modeling process, the project team will have more time to resolve it and develop better solutions. This will result in less ad-hoc solutions and rework in the project. Moreover, by documenting the issue, the designers can prevent facing the same problem in the future. • Information is not interactive. Paper-based information forces people to navigate through information manually, change it in their heads, and manually predict impact of those changes. • Focus of information is not shared. Since much of the information that the team uses or refers to during the meeting,' such as the project specifications and design details, may be private, teams rarely focus on the same information. Even shared information, such as 2D drawings, provides no visual cues to guide the focus of the team because this information is created with single discipline tools. Consequently, participants from various organizations present are distracted and cannot communicate truly relevant information to others. • Views do not visually represent critical relationships. During these meetings, as a team member describes certain features, s/he would walk to a 2D view of the project and point out "where" the work is taking place. Similarly, when the team wants to compare information in design sketches and/or specifications, various team members search through documentation to identify those related items. Relationships between time, space, resources, project requirements and etc. are not captured or communicated in today's traditional graphical representations. This forces the team to spend time comparing documents and trying to understand how this information is related, when simple visualization techniques might easily communicate these relationships. • Views are inappropriate for group use. Usual printed views of project information are designed for individual review and not group review. By nature, most issues discussed in meetings require multi-disciplinary and multi-organizational attention. Yet in all meetings, the meeting leader and the participants had a hard time establishing and maintaining focus because of the problems listed above. Teams need more effective ways to share project information and need more interactive methods of communicating project information that enhance focus on critical and relevant information 19 and communicate critical relationships to better share and compare project information. We believe that, once teams, can perform these tasks more efficiently, they will be better equipped to make decisions and this is where the use of 3D modeling and collaboration for MEP Coordination becomes a handy tool for the project participants. 2.3. 3D Design Coordination Process 2.3.1. Introduction The main objective of performing collaboration process using 3D/4D models is to reduce the lag time between when a question about a design option arises and how soon it is resolved. Reducing this latency in the design process is a must for effective design collaboration using 3D / 4D models. On the other hand, in design coordination meetings, traditionally, each team first explains and describes different positions using 2D Drawings, and then all participants mark their drawings to update and configure their models later on, hence due to the lack of proper interfaces between their models, many of the conflicts are not detected and those detected are not properly documented. As a result, rework in the design phase and/or change order in the construction phase would be needed. Fischer et al. (2000) demonstrates that in current meetings using media which are paper based, 40% of the time is spent on describing project-related information, while only 10% is spent on predictive tasks. However to perform the project with the best quality, study of different design alternatives on the overall project outcome is extremely important, thus more time in project meetings should be spent on predictive tasks. To allocate time to predictive tasks in meetings, time that is spend on describing project related information to ensure all participants comprehensively understand the project, could be reduced. Fischer et al. (2000) states that a reason why the time spent on describing information is exceptionally high is that all the different parties working together on a project use a different view on the related 1 project data. In the past couple of years, effort has been done to establish relationships between different models using modern computer based technologies to overcome these problems. Fox et al. (2000) suggests that such established relationships can be graphically represented in so called interactive workspaces. Therefore performing coordination meetings in interactive workspaces reduces the time spent on descriptive tasks by integrating physical and virtual modern computer technologies in order to enable data exchange and control between applications. (Fischer et ai, 2000) 20 3D modeling and collaboration of the MEP systems which is now being slowly implemented in the industry helps the project participants to overcome the limitations of the conventional 2D (R) coordination process. Currently many in the industry use Autodesk Building Systems (ABS) which is an extended application of AutoCAD for developing the 3D Models of the MEP Systems. ABS has in-built 3D components of the various Mechanical, Electrical and Plumbing Systems used in the building systems and thus enables the developer to develop these models at a fast pace from the 2D Drawings of the project. ABS also has a function for interference detection, which enables the developer to check for any physical interferences in the assembled components in the project and the same can be resolved as and when they are detected by consulting the appropriate project participants. However, ABS also has some limitations and the major one being its incapability to help us check the various constraints that govern the MEP Integration in the project. There is a need for more sophisticated tool such as NavisWorks for determining the clashes and conflicts with regards to the various governing constraints for 3D MEP Coordination Process. The functioning, advantages and limitations of NavisWorks for this 3D Design Coordination process have been explained in detail in Chapters 4 and 5 of this thesis. 2.3.2. Benefits of 3D modeling in M E P coordination process • Ease in Visualization: The 3D modeling and coordination process assists all project team members in visualizing each system and their relation to others. This results in better communication between trades which in turn helps to unveil hidden constraints. In addition, this gives each subcontractor a warning of the critical factors, areas or elements for their system. The construction knowledge implemented in the 3D model reveals the actual availability of space and potential points of concerns and conflicts to the project team, which could not be demonstrated by the schematic details of 2D drawings. • Helps in Integration of constraints with the M E P System: The 3D model provides an integrated view of the design perspective, together with implicit constraints of codes and specifications, and the constructability concerns of the trades and subcontractors. Although a specialty trade might be well aware of all these constraints and might have a clear picture of these critical points of concern, there are many other trades working in the same space that do not have this specialty knowledge and awareness. The 3D modeling process integrates the different design data and assumptions made by individual designers, specialties and consultants in a single environment. This integration will 21 validate the design, expose any missing data and information, and reveal any contradiction or conflict in the design. • Interference Detection: Recent 3D modeling software tools have the ability to identify the interferences / clashes / conflicts (Hard, Clearance, Duplicity, Positioning, Routing, and Codal Provisions) in the modeled system. In addition, the visualization capabilities enable the specialty trades, designers, and coordinators to review and detect these interferences faster, better, and more accurately. When identifying possible solutions, one can instantly make the necessary changes in the systems, and trace the effect of the suggested solutions on other components and systems. Finally, when the model is coordinated and finalized, it is easier and faster to create the sections, elevations, and other necessary documentation of the systems. • Cost and Productivity Benefits: Riley (2000, 2005) concluded by conducting case studies on 4 different types of construction that the savings from eliminating field conflicts were estimated to be worth ten times the investment the project participants had done for coordination and also stated that every hour spent on coordination saved the project participants about 5 hours in the field. Another compelling reason to execute detailed coordination is the sequencing and production information that can be extracted during the process. Trade foreman and superintendents testify that by building the intricate details of a project on paper or in a computer model, they can better visualize the construction process. This visualization allows complex areas of a building to be broken down into a logical order that accommodates crew access and material handling constraints in additional to the physical coordination of building components. As a result, more quality work plans can be developed, and work flow can be planned more accurately. (Riley, 2001) 2.4. Conclusion As we can see, there is wide variation in the level of technology used in the MEP coordination process. At the low-tech end of the spectrum, specialty contractors draft plan-views on translucent media and prepare section-views when necessary. At the other extreme, progressive contractors have used 3D CAD to improve the process. One example of this is the use of electronic plant models, with major benefits on large hydrocarbon and power projects, where an Architect/Engineer completes the entire design. However, design consultants and specialty 22 contractors prefer computer-aided design systems that are tailored to provide specific information for detailing, estimating, fabricating, and tracking their specialty work. Current use of multiple systems (e.g., AutoCAD™, QuickPEN™, MultiPIPE™) tailored to the needs of specific disciplines and trades limits overall effectiveness. The systems are not compatible and electronic data transfer between them usually results in a loss of about ten percent of the data content. Also the systems / tools that are in use in the industry do not have the capability to help in a detailed modeling of the MEP Systems so as to give the ideal solution to all the conflicts that arise during coordination. Also, there is no system that is being used so as to capture the knowledge shared during this coordination process so that it can be used in the future. There is also no mechanism that can help control the budget of the costs that are involved in this coordination process. There is definitely not a lack of technology, but there is a need to better apply the available technology tailored to a specific set of business and technical conditions and also infuse the benefits of this 3D Design Collaboration process into the owners and general contractors so that we can have more efficient and economical projects. 23 Chapter 3: Literature Review on Constraint-Based Modeling and Conflict Resolution 3.1. Constraint-Based Modeling 3.1.1. Introduction All the projects in the world are governed by certain constraints, such as time or cost or design or any other constraint laid out in the project. For a project to be a successful, the project participants have to do a balancing act between all the constraints involved in the project and it's the balance that they achieve which makes the project viable and successful and beneficial to all the project participants. Constraint-based modeling has thus played a very crucial role right from the early days and it's recently that researchers have tried to go more in depth into this aspect. However, there are problems with purely constraint-based systems. Creating complete and consistent constraint specifications is difficult. Defining a complex model by constraints can be a cumbersome task, while applying some modeling operations would produce the same model in a simpler and more natural way. The search for a design solution is, by its nature, a complex one. It is not possible to divide a product into discrete chunks, assign those chunks to individual design teams, have those teams design and build their parts, and expect the product to work the first time. Because of the inherent complexity of design, the teams must check their parts with other design teams, and then re-design their parts on the basis of the constraints imposed by other design teams. Effective and efficient design requires each designer to understand both the internal requirements of their portion of the design, as well as the external requirements imposed by the rest of the product. It is the knowledge of the design constraints that guides the designer to find a solution. 3.1.2. Related Work Nassar et.al (2003) introduced the use of constraint-based assembly operations to help the designer in the generation of building assembly details and in overcoming the need to recreate the detail for each new design. Constraint-based assembly operations are essentially a set of constructive operations that act on components of the assembly to place them in the correct 24 position within the assembly. In architectural practices the details are generally drawn separately from the main plans, elevations, and sections. In constraint-based modeling, on the other hand, the generated detail is based on an abstract 3D representation of the assembly. The designer provides a 3D model of the building in terms of abstract building assemblies. This is analogous to many of the commercial CAD tools (e.g. AutoDesk's Architectural Desktop, Graphisoft's ArchiCad, and Bentely's TriForma, and recently Revit). In this abstract representation of the building, each assembly is modeled as a separate 3D entity. Once the building is modeled in 3D, the constraint-based modeling operations can be used to generate the detail for a specific assembly (or a set of assemblies). Of course, it is possible to generate a complete set of details for all the building. However, this is generally not needed in practice and would make the model undecipherable. Architects usually concentrate and generate details of specific assemblies that are critical or need more explanation. Also, once the detail is generated, the original abstract 3D representation of the building still exists. This allows for viewing the complete 3D model of the building at different levels of detail. Constraint-based modeling operations can help to cut the time it takes to modify the detail and generate new ones and also to minimize the errors resulting from current cut-and-paste practice of details. In order to illustrate this concept, the properties of the abstract 3D representations of the assemblies and the components used in the proposed building assembly detailing system are first presented. Then, the set of constraint-based modeling operations are described next. This is followed by a discussion of the syntax and use of the system along with an example. Finally, the computer implementation is described and conclusions are drawn. 3.1.2.1. Type of Constraints • Mathematical Constraints: Specifications define the first constraints on a new design. The rest of the design process is the search for a solution that satisfies these constraints. Constraints define what form the design will have, and whether a proposed design is viable. The iterative design process is a process of constraint specification and satisfaction, where a designer's knowledge of the design constraints, their satisfaction, or violation, guides the design process. Although constraints used during design include heuristics, tables, guidelines, codal provisions and computer simulations, a majority of those used can be expressed as mathematical constraints. However, it is not enough to define constraints only as equalities, because a majority of the constraints define limitations on a design, rather than stipulating an 25 exact relationship between variables. For example, a possible constraint may be that a beam cannot deflect more than a certain amount. Mathematical design constraints are complex because of several factors. First, constraints can be either equalities or inequalities. Second, although some constraints are linear, most design constraints are highly non-linear; for example, those used to calculate maximum stresses. Third, the size of the problem also complicates the search; for example, a large and complex set of variables and constraints describes the flushness of a seam between two pieces of sheet metal in a car. Fourth, coupled constraints complicate the search for a design solution. Because a change in a design made to satisfy one constraint can result in the violation of other constraints, there is a need for multiple design iterations and continual communication of constraints and their degree of satisfaction. (Thornton, 1996). Constraints from governing Codes and Standards: In Building Systems, and more specifically in MEP systems we have a large number of codes to be followed. Further the types of product used for MEP system also have certain constraints in-built for their installation and efficient functioning. For example, for a Heating Ventilation Air Conditioning (HVAC) unit, key design considerations include space for equipment, space for ductwork, properties of the building enclosure, and noise and vibration. HVAC equipment is generally very large and bulky. The equipment must be accessible for maintenance and replacement. Table 3.1 summarizes the various codes that govern the design and installation and functioning of the MEP system in the building or any project. 26 System Organization or Code rt H V A C • Uniform Mechanical Code (UMC) • Uniform Building Code (UBC) • Building Officials Code Association (BOCA) • Sheet Metal and Air Conditioning Contractors' • National Association (SMACNA) • American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHREA) Plumbing • Uniform Plumbing Code (UPC) • Uniform Building Code (UBC) • Building Officials Construction Association (BOCA) Process Piping • Local Toxic Gas Ordinances (TGO) • Uniform Fire Code (UFC) - Article 80 • American Society of Mechanical Engineers (ASME) - Boiler Code • American Society of Mechanical Engineers (ASME) - Pressure Vessel Code Fire Protection • City fire marshals • Uniform Fire Code (UFC) • City Ordinances • National Fire Protection Association- Article 13 • Uniform Building Code (UBC) • , Building Officials Construction Association (BOCA) Electrical • National Electric Code (NEC) • Uniform Building Code (UBC) • Building Officials Construction Association (BOCA) • National Electrical Manufactures Association (NEMA) • National Fire Protection Association (NFPA) -Article 13 Control • Control device manufactures • National Electric Code (NEC) • Uniform Plumbing Code (UPC) • International Society for Measurement and • Control (ISA) Telephone / Data Communication • Local communications company Table 3.1: The Codes and Standards governing the design M-E-P Systems (Source: Tatum and Korman, 2001) Geometric Constraints: Computer aided geometric modeling plays an important role in the industrial product design process. However, the definition of geometric shapes with today's interactive CAD systems is still difficult and not always as natural as one would like. Most modeling systems are based on an operational paradigm, i.e., geometric shapes are defined 27 by a sequence of construction operations (explicit modeling). These systems do not automatically ensure that the generated shapes meet the specifications, nor do they check whether an operation violates the intended properties of previous operations. To overcome these problems, some modeling systems provide a way of specifying shapes by geometric constraints (implicit modeling). Since Ivan Sutherland developed the first constraint-based drafting system, Sketchpad [Sutherland, 1963], various approaches have been taken to utilize constraints for computer aided design. Constraints give users the ability to specify geometric properties of the models, for example, the length of a side, the volume of a solid, or the parallelism of two surfaces. Whenever a part of the model is modified, the system adjusts the rest of the model such that all the user-imposed constraints remain valid. Sohrt and Bruderlin (1991) took an approach to determine the intended properties of modeling operations and to maintain them during future manipulations. Not only does this avoid possible errors, but it will make the interaction more efficient. If done properly, the system operates according to the users' intentions without them explicitly stating these intentions all the time. The idea is to keep the post conditions of geometric operations as constraints. Since they are not established explicitly by the user, but implicitly as a side effect of modeling operations, they are called implicit constraints. When constraints are imposed on objects or groups of objects (assemblies), they restrict the degrees of freedom for interactive manipulations. Constraints are visualized to make it intuitively clear to the user which operations are possible, and which are not. For example, if the rotational degrees of freedom of an object are restricted to an axis, this axis is displayed. They also demonstrated on representing these constraints in Boolean form and also how to solve the inequalities involved in constraint-based modeling to arrive at a conclusive result for a model. They demonstrated various examples of constraint-based modeling in their work and concluded that by integrating modeling operations with graphical user interaction, constraint solving and group hierarchies one can create an easy-to-use interactive 3D geometric modeling system. Objects can be created, translated, rotated and scaled according to exact specifications with a few mouse- clicks and dragging operations. The intermediate results of such operations are automatically fixed by constraints, so that future modifications will not violate previously fulfilled design requirements. Dependencies between objects are represented by a group hierarchy that is automatically established during constriction. 28 Handles provide the user not only with an interactive transformation facility, but also with feedback about the degrees of freedom that are left for an object. If dependencies are not sufficient, simultaneous systems of constraints can be specified explicitly and solved with a two-phase symbolic constraint solver. Constraints are not only helpful for constructing models, but they are seen as an integral part of the model. This is particularly useful for models of assemblies with moving parts. Also, by integrating constraints into the model, design teams can communicate incomplete specifications for further work on of the model. Constraints ensure that earlier design decisions are not violated by modifications in later design stages. Recipients of model data can not only look at the components of the model, but also see how these components are attached to one another. They can modify the model within its degrees of freedom and even view an animated display of the working model. Design and Modeling Constraints: Design and modeling constraints are present in all projects. The only thing that differs is the variance they have in the overall execution of the project. In the case of the MEP coordination process, it was the study by Tatum and Korman (2001) that made other researchers do more exploration into this idea of knowledge-based reasoning for the MEP Coordination Process. Tabeesh and Staub-French (2005), in their work, developed a framework to formalize the MEP coordination knowledge they collected in a way that conveys the context of the knowledge, represents the generality of the knowledge, enables reuse of the knowledge across multiple projects, and potentially supports computer-based implementation. This framework builds on and extends the knowledge items identified by Korman et al. (Korman, 2003). This was the only time that the work done by Korman was applied to classify the knowledge captured actively and firsthand from an MEP coordination process on an actual project. Tabeesh and Staub-French (2005) added some new attributes based on the facts of this case study, industry terminology, and the knowledge items used in other constructability frameworks. They were more involved with the construction experts and therefore the developed knowledge attributes relate more to the construction domain. 29 Figure 3.1: The three dimensions of the MEP Knowledge Framework (Tabesh and Staub-French, 2005) Tabesh and Staub-French (2005) also defined the attributes they had extended from the earlier work done by Tatum and Korman (2003). Many of these constraints are valid in the context of the modeling and coordination tasks that they are used for, and they tried to account for that in their classification. Essentially, the modeling and coordination tasks represents "how" the constraints affect the coordination process, whereas the knowledge attributes represent "why" the constraints affect the coordination process. In addition to that, they also represented the modeling and design constraints with respect to the knowledge framework they defined in their work and the same are illustrated below in Table 3.2. 30 System Modeling and Coordination Constraints • Knowledge Domain Knowledge Attribute Modeling & Coordination: Task Korman's Knowledge attribute 1 The ducts should maintain a minimum clearance from the adjacent walls and slabs. Construction Tolerances Routing Clearance 2 The ducts, needing the largest supports, should be positioned closer to the slab. Construction Productivity Support System Mechanical In case of external insulation of equipment, positioning should account for installation ^ S P 3 C 6 Construction Installation Space Positioning Insulation Installation Space Mechanical 4 The code implies the thickness of the duct's external insulation or internal lining. Design Performance Detailing Insulation Mechanical 5 The minimum standard radius of a round fitting elbow can not be less than its diameter. Operation Performance Mechanical Construction Fabrication Mechanical 6 It is better to install the ducts first, due to their size and inflexibility. Construction Productivity Sequencing Sequence Plumbing - Process Piping 7 U-shaped over passing creates air traps in pressure pipes; Avoid them. Operation Performance Routing Plumbing - Process Piping 8 The RWD line can not run bellow the false-ceiling elevation. Design Aesthetics Plumbing - Process Piping 9 In assigning space to pipes, should account for installing insulation. Construction Installation Space Insulation Installation Space Plumbing - Process Piping Pipes have higher maintenance frequency than ducts, therefore they should not be ^ positioned above the ducts. Operation Access Access Sequence Plumbing - Process Piping 11 RWD pipes should maintain a 1% minimum slope. Design Performance Slope Plumbing - Process Piping 12 The minimum standard radius of a round fitting elbow can not be less than its diameter. Operation Performance Detailing Plumbing - Process Piping Construction Fabrication Plumbing - Process Piping 13 The code implies the thickness of the insulation around the pipe. Design Performance Insulation Plumbing - Process Piping 14 The placeholder used to hold a 4" vertical stack pipe in a wall, will need at least a 7" wall Construction Variance Plumbing - Process Piping 15 The RWD routing should connect the vertical stacks of the adjacent floors. Design Function Validating Design Function Plumbing - Process Piping All Waste/Sanitary Drain stacks have to be connected to the vent stacks going up from 1 6 that floor Design Performance System/Function Electrical The cable tray has to maintain a 60 cm horizontal clearance on one side to provide 1 7 access to cables. Operation Access Layout Access Clearance Electrical Construction Installation Space Electrical The cable tray has to maintain a 30 cm vertical clearance on top side to provide future 1 8 accessibility to cables. Operation Access Access Clearance Electrical Construction Installation Space Electrical 19 The cable tray has to maintain a 15 cm vertical clearance zone anywhere on top side. Operation Safety Performance Clearance Electrical 20 The number of maximum 90 degree elbows from start to finish for a conduit is four. Operation Performance Routing Table 3.2: The design and construction constraints identified in the case study, classified according to the knowledge domain, knowledge attributes, and modeling and coordination tasks (Tabesh and Staub-French, 2005) For each building system, they presented the modeling and coordination constraints (Column 2), the knowledge domain (Column 3), the knowledge attributes (Column 4) , and the specific modeling and coordination task (Column 5). They also illustrated the functionality of their knowledge framework by using an example (conflict) from their Case Study on UBC Chem Bio Project. However, I found that although the framework defined by Tabesh and Staub-French is quite good, it is missing one of the key attributes which is the Cost of MEP Coordination. In my opinion, every project is constrained by cost and it's essential for us to incorporate this attribute too in the framework. Riley et al. (2005) did a comprehensive study on MEP Coordination Costs as shall be discussed in depth in Chapter 6 of this thesis. Declarative Constraints: In the study on constraint-based modeling for building systems, Nasar et al. (2003) introduced the term, Declarative constraints which relates the location of two objects together. Declarative constraints can be used to restrict the locations or orientations of certain objects in the model. For example, a mate constraint can be used to ensure that the beam object is geometrically located flush with a column as seen in Fig. 3.2. In this case, the mate constraint takes four parameters: the two objects to be constrained and two vectors on the objects to describe how to mate them. Once the constraint is specified, any modifications to the assembly must comply with the set constraints, and a new assembly detail can be generated. The new details reflect the correct location of the components. So if the size of the beam in Fig. 3.2 changes, for example (or the column is moved or resized), the model will be updated to reflect the new size maintaining the flush constraint. The mate constraint in Fig. 3.2 is only one type of constraint. Loadw 4 7\ D IZ 171 BEAM -Male Constraint MATE (OBJECT I, OBJECT2, VECTOR 1, VECTOR 2) COLUMN Figure 3.2: Example of Constraint 32 Various generic constraint sets have been proposed in the literature. However, there are, as yet, no standards for specifying or representing constraints [Hower and Graf, 1996]. The constraints are divided into two main groups: orientation and position. The position constraints are used to define distances between two points as constraints. They specify the distance measure from a reference entity to a target entity. The orientation constraints are divided into five types: parallel, perpendicular, angle, coplanar and coaxial. Another set of declarative constraints is offered in a commercial constraint-based modeler, AutoCAD Mechanical Desktop. This program allows users to specify four kinds of constraints: AMINSERT (insert), AMANGLE (angle constraint), AMFLUSH (flush constraint), and AMMATE (mate constraint) as shown in Table 3.3. Mechanical Desktop was used as the constraint-based engine for the prototype system developed in this research, and hence these constraints are used here. Constraint • • S i v • --"Description, '•*if»»''. • Mate To join points, axes, planes, or non-planar faces. Insert To align two circles, including their center axes and planes, use the Insert constraint. Flush To make two planes coplanar with their faces aligned in the same direction, use the Flush constraint. Angle To control an angle between two planes or two vectors, use the Angle constraint. Table 3.3: Constraints in Mechanical Desktop Although the discrete parameters in traditional constraint-based modelers like Mechanical Desktop can be changed (e.g. the length or width of an element, a radius of cam, etc.), the parameters of the declarative constraints (the CADREPs themselves) have to be changed manually. Furthermore, when modeling building assemblies using constraint-based modeling, one often needs to resort to a number of steps in order to achieve the final effect [Nassar et al., 1999]. In building assemblies, for example, there are usually repetitive objects. For example, the CMU units or the metal ties are repetitive objects with the same solid model. If we were to specify these units separately, the modeling time would increase significantly. A solution might be to define a 3D ARRAY operation that can used to create objects and then constrain the final set of objects as a whole using the traditional geometric constraints. In addition, the 33 sequence of the assembly process itself could be important for further analysis of the properties of the objects. Therefore, a set of constraint-based assembly operations is proposed. These operations can be used to specify the sequence of operations to constrain the locations and orientations of certain objects in relation to others. The set of constraining operations are constructive steps that place geometric elements relative to each other. This approach is often called constructive specification [Nassar et. al, 1999]. The operations and the constraints associated with them are shown in Table 3.4. Operation Geometric work-feature parameters on reference Geometric work-feature parameters on target Building y| parameters Example Layout One point, one line One point, one line Spacing Metal ties, fixtures Assemble One point, one line One point, one line - Bolts, screws Cover One point, one line One point, one line Start point, end point Angle, spacing, overlap Tiles, sheet, rock Cut One point One point, one line Angle Sawing wood Stack One point, one line One point, one line Start point, end point Vertical joint stacking Horizontal joint stacking Masonary Table 3.4: The defining constraint operations In summary, constraint-based design uses constraints to describe a design, and uses computational methods to search for a feasible and/or optimal solution I design. In addition to the above mentioned constraints, when the individual design disciplines begin their integration of the 2 D or 3 D drawings of the respective MEP systems by sitting with the other, it results in a whole new dimension of conflicts for the design disciplines and, in order to resolve these conflicts, the conflict resolution mechanism starts. 3.2. Conflict Resolution Mechanism 3.2.1. Related Work Mark Klien (1990), in his paper on conflict resolution, proposed a model of run-time conflict resolution in cooperative design that had advantages over existing conflict resolution approaches. This model was designed keeping in mind the mechanical engineering industry; however, we as civil engineers can adopt some aspects of the model for MEP coordination process as MEP 34 coordination is also a cooperative design. It is based on the notions that conflict resolution expertise can be captured explicitly, and in addition can be organized usefully into a taxonomy of conflict classes and associated conflict resolution strategies. The study consisted in essence of recording the activity of architects engaged in the design of a home, and then analyzing it to gain insights into the cooperative design process in general, as well as conflict resolution in particular. In the study, Klien also divided the conflicts into 2 categories viz; Competitive Conflicts, in which each party has solely their own benefit in mind and has no interest in achieving a globally optimal situation if such a solution provides them no added personal benefit and Cooperative Conflicts, in which the parties are united by the super ordinate goal of achieving a globally optimal solution, which often requires sacrificing personal benefit in the interest of increased global benefit. Resolving conflicts is a critical requirement for a cooperative design system that realizes parallel interaction among different sources of expertise. Since the participants in a cooperative design activity generally have different perspectives (e.g. different goals, different ways of achieving similar goals, etc), they will occasionally come into conflict concerning some aspect of the design. One design agent may specify that a given part have a particular shape to maximize strength, while another may specify a different shape that simplifies the operations needed to machine the part. In human design teams, the participants will usually then utilize conflict resolution strategies they have developed over the course of their working lives to produce a design that is satisfactory with respect to the different sources of expertise represented on the design team. Not all conflicts may be discovered at design time, of course; some may only become apparent when the product is actually built and used. Computational models of conflict resolution range over a spectrum that can be divided into five categories as listed below, however these categories vary in the extent to which conflict resolution expertise is made explicit and available for use during run time. • Development-Time Conflict Resolution: Traditional knowledge-based systems rely on all of the potential conflicts between different perspectives being resolved at development time. The conflict resolution knowledge utilized by the experts is then implicit in the individual conflict resolution decisions made during development. While this approach can be used in cooperative problem solving systems, there are a number of advantages to allowing conflicts among knowledge sources to be detected and resolved at run time using explicitly represented conflict resolution strategies. 35 o Reduced Development Time o Improved Comprehensibility o Increased Extensibility o Increased Flexibility o Involving Human Problem Solvers The fundamental advantage of run-time conflict resolution, then, is that it constitutes a more realistic model of cooperative problem solving than does run-time conflict resolution, both in the sense of constituting a better model of human group problem solving, as well as in the sense of reducing the complexity of the individual design agents to more manageable levels. In 2D MEP coordination process, the project participants sit down to check for conflicts only after they finish the first draft of the 2D Drawings and this delays the entire coordination process. In the use of 3D modeling for the MEP coordination, this concept of development-time conflict resolution is used as the designers can do simultaneous checking for the conflicts while designing or placing the components. Backtracking-Based Failure Handling: Conflict resolution in non-distributed design and planning systems is generally known as failure processing. In backtracking-based failure handling, when conflicting design commitments are made, the control flow is traced backwards to some decision point, and some previously untried alternative is chosen. This approach suffers from the drawback that the backtracking is done without the guidance of domain-specific conflict resolution knowledge. As a result, excessive amounts of backtracking may be needed before a conflict resolution is found, and there is no guarantee that the resolution found is in any way optimal. In 2D coordination, one does the back tracking of the conflicts by reverting back to the previous revisions of 2D drawings of the MEP systems and this can be a tedious process, using the 3D modeling technique for coordination reduces this time as the modeler saves the drawing files in separate names and one can thus easily revert back to the conflicts found in that revision of the 3D models. Numerically-Weighted Constraint Relaxation: Systems that perform conflict resolution based on numerically-weighted constraint relaxation include the ISIS system for factory scheduling and the GARI system for producing plans for manufacturing parts. These approaches rely on assigning static numerical weights to different constraints on the final design. When constraints come into conflict, the systems attempt to find the set of admissible constraint relaxations that minimizes the reduction in the total constraint weights. While this 36 approach has shown some success, it suffers problems analogous to those exhibited by other numerical weighting approaches, such as plausibility factors. These problems include: o Acquisition: Human experts find it unnatural to express conflict resolution expertise using a numerical formalism. o Consistency: If the constraint weights are derived from multiple experts, we cannot be sure that the different experts used the same semantics when assigning the weights. o Modifiability: Changing the desired conflict resolution behavior in a design system can require coordinated changes to a potentially large set of constraint weights. o Explainability: The reasoning behind a given conflict resolution decision can only be expressed in terms of constraint weights, rather than in terms of the domain entities used to explain design commitments. This makes these conflict resolution decisions more difficult to understand. o Context Dependence: The importance of a given constraint may vary with the situation, but the use of a single numerical value commits us to a single context-independent evaluation. This makes it difficult to capture situations where the importance of a given constraint is context dependent, i.e. is determined by an interaction among the participating constraints. This concept can be very effective if we can complement the same with the integration of drawings process, as this can help us understand the constraints that are more of priority among the various MEP coordination process related constraints. 3.2.2. Conflict Resolution Strategies 3.2.2.1. The Theoretical Approach Klien (1990) in his study also described each conflict resolution strategy, and also indicates when necessary the applicability conditions for that strategy. • Abandon Goal: o Abandon Goal Justifying Action: Abandon the goal justifying a design action. This is appropriate when we want to • reduce use of a resource (abandon the goal justifying the plan that uses that resource) • resolve conflicting recommendations (abandon a goal justifying one of the conflicting recommendations) 37 • resolve a negative critique of a design action (abandon the goal that justifies the critiqued design action). o Abandon Goal Justifying a Critique: Abandon the implicit threatened goal justifying the negative critique. A typical example for this can be changing the type of duct work to resolve a conflict from fixed to flexible is abandoning the goal of the specifications of the system but we are justifying the action as we want to resolve the conflict. Try Alternate: o Alternate Plan: Find an alternate plan for a goal. • For Critiqued Action: Find an alternate plan for a goal justifying a critiqued design action that no longer threatens the goal justifying the critique. • Less Resource Intensive Plan: Find a plan that uses less of the resource that the threatened goal wishes to preserve. • For Conflicting Recommendations: Find an alternate plan for satisfying a goal justifying one of the conflicting recommendations. • Consistent with Existing Constraints: The alternate plan does not conflict with existing constraints on the design. • Inconsistent with Existing Constraints: The alternate plan conflicts with existing constraints on the design. o Alternate Sub goal: Replace the goal justifying a design action with an alternate sub goal for satisfying the higher level design goal involved. This is appropriate when the higher level goal has several viable sub goals. A typical example for this can be changing the shape of a conduit so that it fits into space allocated for it to move to the next floor level. Add Detailing: o To Satisfy Threatened Goal: Find a plan to satisfy the threatened goal justifying the negative critique of a design action. • Inconsistent With Critiqued Action: Find a plan for the threatened goal that is inconsistent with the critiqued action. • Consistent with Critiqued Action: Find a plan for the threatened goal that is consistent with the critiqued action. • Alleviate Resource Shortage: Find a plan that satisfies the threatened goal by alleviating the shortage of a limited resource. 38 • Make More of Resource Available: Find a plan that makes more of the resource available. • Reduce Use of Resource: Find a plan that reduces the use of the resource. • Use Less: Find a plan that reduces the amount of resource consumed. • Goal Overlap: Find a plan that makes a given chunk of resource satisfy several goals that were previously satisfied by separate chunks. • Change Number-Valued Feature: Find a plan to increase/decrease the value of a design feature that is too small/big to satisfy the threatened goal. o Satisfy Goals for Conflicting Recommendations: Add detailing that allows the satisfaction of both the goals justifying conflicting recommendations. • Duplicate Functional Resource: Find a plan that divides the conflicting constraints on a functional resource into mutually consistent sets, and then produce one copy of the resource to satisfy each set of constraints. A typical example for this can be Request for information (RFI) for any missing details in the drawings of the MEP systems. Partial Goal Fulfillment: o Two-Sided Compromise: Partially satisfy both conflicting goals. This is appropriate when all sides involved have some degree of flexibility. • Establish Tradeoff and Ask Client: Frame the conflict as a tradeoff and allow the client to pick a compromise point that is most satisfactory. • Heuristic: Use a heuristic to find a tradeoff point, such as "find the average of the conflicting constraints on a numeric design feature". • Numeric Optimization: Use numerical optimization techniques. This is appropriate when evaluation functions are available. • Resource Tradeoff: Allocate some of the resources used by one goal to the conflicting goal. This is appropriate when the plans for the conflicting goals both use a limited resource. • Minimize Degree of Goal Violation: Minimize the extent to which one or both goals are violated. • Minimize Area: Minimize the spatial area over which the goals are violated. 39 • Minimize Time: Minimize the amount of time for which the goals are violated. • Most Important Subset: Satisfy the most important subset of the goals, o One-Sided Compromise: Partially satisfy one of the conflicting goals, and completely satisfy the other. • Penalize Biggest Resource User: Find a plan to partially satisfy the goal that justifies the heavy use of a limited resource in a way that reduces the use of that resource. In another study, Wiebe, E.N. (1999) illustrated that the mechanical design process consists of three parts; Ideation phase, the design requirements are embodied in potential geometric forms and material specifications, Refinement stage, the modeling strategy developed in the ideation stage can be applied to the actual construction of the model and, Implementation stage, the geometric database, representing the design, is transformed in ways that help support the manufacture, sale, and support of the product. These transformations might include the creation of traditional working drawings from the model or the creation of CNC code for machining molds. These parts happen both concurrently and cyclically towards a final design solution, and 3-D modeling software plays a role in all three phases. The above literatures provided me with several insights into conflict resolution in cooperative design which can be applied to MEP coordination process: • conflict resolution plays a central role in cooperative design • conflict resolution knowledge can be viewed as a form of problem solving expertise • we need to represent the design rationale to support conflict resolution • knowledge acquisition in cooperative design presents special challenges, and requires additional techniques compared to traditional knowledge acquisition • the earlier the conflict is detected, the earlier it can be resolved and thus saves time and cost incurred in the coordination process and has less impact on the productivity of the project. 40 3.2.2.2. The Practical Approach (Excerpts from Other Industries) The equivalent of MEP coordination in the product design and manufacturing industry is required for ships, aircraft, and automobiles, which require coordination of multiple active systems located within their structure. For aircraft and ships, the most common procedure for coordinating mechanical, electrical, and plumbing systems is to designate pathways for each system during the design of the product. Engineers then route the systems within these reserved spaces to required locations and show them on drawings. Overlays and section cuts show the coordination of the systems. The slow and expensive process previously required a full-scale model of the aircraft to identify interferences. Once engineers determine an optimal arrangement, engineers repeat results exactly for each product produced. This process changed dramatically with the design and manufacture of the Boeing 777 airplane. Engineers used the CATIA™ design software to design and route all systems on board the aircraft in a 3D model. This enabled Boeing to complete a virtual design without building a full-scale mock-up of the aircraft [Dornheim, 1991]. For automobiles, specifically engine design, a process known as incremental design entails never starting with a new design. It always uses an existing design as a basis for the new design and makes incremental adjustments. The automobile industry is very quick to move to the detailed design stage by choosing to produce prototypes rather than by producing configurational design drawings. Table 3.5 summarizes the coordination of active systems in the above mentioned products. Structure * Coordination Technique S Ships Overlay of translucent drawings with section views. Aircrafts Virtual 3D product model in CATIA design software. Automobiles Incremental design and full-scale 3D-product model. Table 3.5: Coordination of active systems (Source: Tatum and Korman, 2001) In the next chapter, I will be describing the growth and analyzing the current state-of-the-art software that is being used for MEP conflict detection in the industry. 41 Chapter 4 : Review of State-of-the-art Software for Conflict Detection and Management in MEP Systems Coordination 4.1. Introduction During the early and mid-1980s, CAD was gaining ground and becoming an efficient alternative to the drafting table. With the increased use of CAD, architects were continuously devising ways to automate drafting and design tasks in order to increase their efficiency. Repetitive tasks were automated using predefined scripts, utilizing the various scripting languages offered in the CAD systems (e.g. AutoCAD's AutoLISP). Object-oriented data was added to lines, arcs and circles, and systems began recognizing them as doors, windows and doors. Object data was then extended to the third dimension, so architects could work in 2D and 3D. A number of software tools were devised in which architects can define their designs in 3D and the complete object model is maintained by the system. This started with simple "house modeling" software marketed to help non-architects define their "dream house" (e.g. Home Architect, Home Designer, etc.). The idea was then extended to professional software like Triforma, Architectural Desktop and ArchiCAD. Concurrently, in the mechanical design realm, parametric modelers were being introduced. The concept behind these modelers is that a user defines a set of parameters that in turn drives a 3D model. This means that changes in any parameter are propagated to the rest of the model. Additionally, various 2D details can be extracted from the model. In the architecture realm, Revit [Revit's Users Manual] first introduced this concept commercially. Revit is a parametric modeler that acts on parametric components (e.g. doors, windows and doors), and annotations (e.g. dimensions and grids) and parametric views (e.g. plans and sections) to ensure bidirectional association between the elements of design. When changing the location or size of a window in a floor plan, for example, the change is reflected in all views like elevations and perspectives. If a dimension measuring from the end of a wall to the center of a window is changed, not only will Revit move the window, but also any other windows parametrically related to it. This parametric model of the building, which is driven from a single integrated database, is what makes Revit unique. Simultaneously in the mechanical design realm, constraint-based modelers, like Mechanical Desktop [Mechanical Desktop Users Manual], were being introduced and used. Constraint-based geometric modeling entails specifying geometric constraints to control the locations of the components in the assembly. Consequently, any future modifications of the components are governed by these constraints. 42 The constraints are used to relate two components within an assembly to control their positions and orientation relative to one another. Similar concepts in architecture were described in a number of research studies as early as the 1960s [Sutherland, 1963]. Gross [1996] described a system where building components can be assembled using "Lego-style" constraints that guide the placement of the components in the building. The constraints mainly relate to the various grids and modules used for the various systems in the building. Harfmann and Chen [1993] also proposed a system where the various components of the building are linked together using constraints. An integrated database that stores all this information is maintained by the system. Frazer [1985, 1997] described how constraints could be used to describe the rules of the physical and spatial structure of architecture designs, which he called plastic modeling. Kilkelly [2000] described a comprehensive approach for construction drawings. The approach employs object-oriented entities to specify the composition of construction drawings and details. 4.2. Computer Tools In facility design and construction as well as product design and manufacturing, designers use computer tools to automate specific design tasks related to the product cycle. Most of these computer tools have focused on detailed design/simulation tasks related to the product cycle. However, more recent computer tools have been able to assist with additional tasks related to the product cycle. These tasks include detailed design to determine a preferable work method and sequence and configurational design to identify an optimal arrangement of objects. To pursue each new capability, researchers have employed knowledge-systems software technology that allows knowledge integration with computer representations of facilities or products. This software uses a knowledge framework and reasoning structure to link an object (component) with a particular set of knowledge. The following examples illustrate attempts to integrate knowledge with geometric models and bridge the gap between design tools and geometric models using knowledge-based systems. 4.2.1. Facility design and construction Traditionally, construction has lagged behind other industries in the use of computers. In recent years, 3D CAD models have become more popular in the design and construction industry. These tools are able to produce a complete product model, which assists in the configurational 43 design task. Currently, there are many software products related to the design of MEP systems. Tables 4.1 through Table 4.3 categorize the major commercial tools by their primary application in the product cycle. These tools allow for faster design in detail, as they contain libraries of components stored in databases for use in building a specific plant model. However, these current commercial tools do not allow full integration of building systems nor are they able to use knowledge frameworks and reasoning structures to assist in the configurational design task. Many of the tools have the ability to detect both physical interferences and clearance violations. However, they rely on knowledge from coordination teams and do not provide feedback. Tool-Name ' *: Capabilities '*f-5'"" SPIPE - Plumbing design software (Elite Software Development, Inc.) Computes optimal pipe sizes for hot and cold-water domestic water supply. Capabilities include system performance calculations, automated generation of bill of materials, and labor estimates. FIRE - Fire sprinkler design software (Elite Software Development, Inc.) i Performs all necessary hydraulic calculations as required by the NFPA 13; capabilities include estimating sprinkler head requirements and calculating optimal pipe sizes. Ductsize - Duct design software (Elite Software Development, Inc.) Calculates optimal air conditioning duct sizes for round, rectangular, and flat oval ducts, including total duct section surface area and weight based on design procedures. Table 4.1 - Commercial tools for detailed design/simulation task 3D models also allow for increased visualization of design. Drafters represent all components and objects visually. Individuals are able to visualize rather than conceptualize difficult geometric configurations [Hill, 1998]. Visualization helps with some coordination issues; however, the benefits from visualization techniques are limited by the knowledge of those looking at the model. For example, extremely congested areas are difficult to visualize. It is often difficult to determine clearances between components and project teams require many projections and sections to identify interferences. 44 Tool Name Capabilities Softdesk - Building Services Edition (Autodesk Corp.) AutoCADTM-based design tool for mechanical, electrical, and piping systems. Capabilities include automatic generation of schedules and bill of materials as well as interference detection. 3DM - Bechtel 3D System (Bechtel Corp.) 3D computer modeling system that includes capabilities for interference detection, drawing creation, generation of bill of materials, and model verification. Also provides capability to design and model mechanical, electrical, and piping systems interactively. SolidBuilder (EaglePoint Software) Residential and light construction application that creates the 3D model and automatically frames using wood, logs, steel, concrete, brick/block. Capabilities include automated cutting and layout lists, bill of materials, and quantity takeoff. PlantSpace (Bentley Systems, Inc.) 3D modeling software for mechanical, electrical, and piping. Provides for interactive specification-driven design process for process and power plants. Capabilities include detection of both physical clashes and clearance violations. CCPlant - Plant Design Software (Silicon Graphics, Inc.) Fully integrated, object-oriented, rule-based modeling software, covering piping, equipment, structural, and ductwork. Allows for concurrent design including interference detection, layout verification, and standards compliance. ArchT (Ketiv Technologies, Inc.) AutoCADTM-based object-oriented software that aids in the automating the design of building components that includes component databases containing specified properties. Table 4.2 - Commercial tools for configurational task Tool Name Capabilities QuickPen (QuickPen Intl.) 3D sheet metal and mechanical system design software, which assists in H V A C dry layout. Capabilities include automatic collision checking, automated generation of 3D spools, data transmission to plasma cutters for fabrication, and automated generation of bill of materials. AutoPLANT (Rebis - Industrial Workgroup Software) AutoCADTM-based, object-based, 3D piping module that assists in design and modeling of piping networks. Capabilities include automated isometric generation program, including automatic dimensioning, annotation, and bill of materials. CATIA™ (IBM) CATIA™ Version 5 allows users to capture and reuse corporate expertise throughout the product life cycle. Combines the power of explicit rules that define the product behavior, with interactive capture of design intent as the design is built. The system acts as an expert advisor to guide you through the task, warning you of rule violations and conflicts. AutoRouter (DesignPower, Inc.) Algorithmic optimization routing software for process and chemical plants. Routes pipes direct from P&ID to 3D piping. Capabilities include automated nozzle placement and automated generation of C A D drawings. Table 4.3 - Commercial tools for both detailed design/simulation and configurational tasks 45 4.2.2. Product design and manufacturing In the product design and manufacturing sector, computer tools have focused on one particular aspect of design and manufacturing. Traditionally, the purpose of these tools was to integrate specific aspects of design and manufacturing. Electronic engineers developed the design tool Magic™, a VLSI Layout System, to assist in integrated-circuit design [Ousterhout et al, 1984]. The tool assists designers in locating design violations based on manufacturing criteria. The system incorporates expertise about design rules and connectivity directly into the layout system, thereby providing feedback to the designer during the design process. The integrated circuit design problem is much like a quasi three-dimensional problem with multiple layers; therefore, it does not deal with many similar issues that MEP coordination must. Due to the nature of integrated circuit design, the tool is limited in its visualization capability. 4.2.3. MEP Coordination Tool According to Tatum and Korman (2001), Heuristic Reasoning and Model Based Reasoning provide a more robust reasoning system then Case Based Reasoning because they rely more heavily on individual component attributes rather than solution sets as used with case based reasoning. Based on these reasoning structures, they developed a J A V A ™ based application MEP Coordination Tool and used this tool in test cases. However, this tool had its own set of limitations which are as below: • The tool is not commercial software; was designed and developed for research purposes and is limited in executing certain capabilities. • The primary limitations are the basic structure of the user interface. Compared to commercial software such as AutoCAD™ and QuickPEN™, the user interface only allows limited software links; furthermore, the links that exist support a relatively low level of data exchange between software applications. • The graphical display of components used in the prototype tool is only able to support a two-dimensional rendering. As described, data transfer to VRML provides a three-dimensional visualization capability; however, movement of components is not possible in VRML. • The elementary geometric representation limits the reasoning ability of the prototype tool. The prototype tool was designed to represent objects as rectilinear solids, not as they 46 actually exist in the real world. For example, the prototype tool does not correctly represent cylindrical shapes, but uses their upper and lower bounds. A more sophisticated geometric reasoning algorithm is required to allow the reasoning structure developed to take full advantage of the geometric reasoning capabilities. • In addition, further development of the user-interface is necessary to increase user-friendliness, simultaneous access to multiple software, graphical representation, and three-dimensional rendering. • The test cases also revealed two primary deficiencies of the tool. First, the tool should provide more information about the reasoning used to resolve interferences. The tool needs to provide more clarification regarding the rationale it uses to make suggestions. Since the prototype tool symbolically represents knowledge in the tool, the raw knowledge is not available to the user. The users focus on what they can visualize, as they do in the actual coordination process. The prototype tool needs a better means to provide this additional information, which contractors communicated verbally during the coordination meetings. • Second, users require increased visualization capabilities. This need stems from the inherent nature of MEP coordination. Components actually exist in a 3D world. In the actual coordination process, contractors perform coordination on flat 2D drawings. The capability to integrate a three-dimensional geometric representation of components with reasoning proved to be extremely valuable in identifying interferences other than physical clashes. Extended interferences were much easier to visualize in the 3D environment and the tool was able to provide additional information regarding functional, temporal, and future interferences. This is not available on coordination drawings. These limitations of the tool developed the need to review the state-of-the-art software available and being used currently in the industry for MEP Coordination Process and more specific to for Conflict Detection as the basic purpose of MEP Coordination is to resolve the conflicts that would occur on the field once the drawings of the Mechanical, Electrical and Plumbing Systems are integrated together to enhance my understanding in how much growth has happened in this sector after the idea of a MEP Coordination Tool was developed by Tatum and Korman. In the following sections, I will be reviewing the two mainly used state-of-the-art software tools in this field viz. Autodesk Building System (ABS™) and Navisworks™. ABS™ is an extended 47 application of AutoCAD while Navisworks is a fairly new tool that is rapidly gaining popularity with the industry professionals for conflict detection in MEP Coordination Process. 4.3. Autodesk® Building Systems (ABS) (executed from ABS Users Manual) 4.3.1. Introduction Autodesk® Building Systems™ (ABS) is an AutoCAD®-based building design and construction documentation solution for MEP engineers, designers, and drafters - improving productivity, accuracy, and coordination. The basic purpose that ABS tends to achieve is: • Improve Workflow Efficiencies with Increased Productivity: Flexibly implement Autodesk Building Systems, adapting it to existing workflows to improve the design process. Move from schematic design to documentation faster through automated construction documents with an object-based model. Reduce drafting time by working in an intuitive design environment with intelligent engineering objects. • Streamline the Design Process Through Greater Accuracy: Incorporate actual industry-based parts and equipment into design layouts for more efficient design development and construction documentation. Automatically exchange engineering data among model and third-party analysis, fabrication, and estimating applications. Reduce requests for information (RFIs) and costly design changes in the field with construction documents that are dynamically linked to the design model. • Work Effectively with the Extended Design Team for Increased Coordination: Help ensure coordination with architectural and structural designs prior to construction with instant feedback from the object-based model. Clearly communicate design intent with a realistic representation of building systems directly from the model. Collaborate seamlessly with the extended team using the industry-leading DWG file format. 4.3.2. Conflict Detection Mechanism 4.3.2.1. A n Overview After drafting your building systems layouts, you need to check for valid connections between parts, completed runs from start point to endpoint, and interferences between other building systems components or structural members. You may also need to verify specific object connections. ABS provides tools to assist you in checking your layout: 48 • Disconnect Markers show invalid connections between components by displaying a defect marker symbol at the invalid connection points. • Show Connected Run displays a complete run of connected components by highlighting the run from start to end. • Show Connected Objects highlights the objects that are connected to a selected object. • Show Circuited Devices highlights the devices that are connected to a selected circuit. • Interference Detection shows interferences between the Building Systems or AEC structural objects by highlighting the intersecting portions of the objects. 4.3.2.2. Interference Detection Interference detection finds spatial interferences between Building Systems objects and structural members, such as columns, braces, and beams, in your drawing. Identifying interferences when working with complicated design layouts tends to be time consuming in 2D. Applying interference detection when drafting your layout can help to prevent laying out components of your building systems in physically impossible locations, such as running a water pipe through a heating duct. Detecting interferences between Building Systems objects and AEC structural members is critical for construction, because structural elements of a building are generally difficult to move. You can also use interference detection across external reference files. . . hiqhliqhted interference Figure 4.1: Highlighting an interference condition ABS interference detection finds only hard interferences that are critical for design. If insulation is applied to your Building Systems objects, the thickness of the insulation is included in the interference detection. The detected interferences are shown by highlighting the intersecting portions of the objects that were drawn last. The interference highlighting color is red by default. 4 9 Prior to applying interference detection, you should temporarily change the color of any Building Systems objects and AEC structural members to a color other then red. To apply interference detection: 1. On the Format menu, click Options. 2. In the Options dialog box, click the Building Systems Layout Rules tab. 3. Under Building Systems Interference Detection, select Alert. tions Current profile: Building Eng...g - UK Metric [p Current drawing: Drawingl.dwg AEC Project Defaults ABS Layout Rule: ABS Crossed Objects ABS Elevations ABS Catalogs ABS Tooltips < > j - Connection Test Mismatch Action to take when connection tests fail: © 0 Do not make connection 0 Prompt for user input r\ Automatically match and make connection \ Part Selection 0 Use Catalog Parts Only ® f j j j j t a n d a , d 0 Use Non-Standard Parts Collision Detection-© • Alert Color: 1 - Red OK Cancel Help Figure 4.2: Options Window of ABS 4. If you want to change the interference highlighting to a color other than red, click the [...] icon and select a different color. 5. Click OK. 6. On the command line, enter REGEN and the interferences are displayed in the Dimensional drawing of the Floor Level. 50 4.3.3. Critique of A B S 4.3.3.1. Benefits • ABS is an extended application of AutoCad™ and AutoCAD™ is a widely used application for developing 2D drawings in the industry, developing a 3D model of the already developed 2D drawing is a far easier job as most of the components used for MEP Systems are predefined in ABS, it's more user friendly to develop these models. • ABS recognizes the thickness necessary for insulation around the objects, if you define that in the beginning of your design. • ABS does help to a certain level in detecting physical interferences among MEP systems and thus helps the user to change the model to resolve these conflicts. 4.3.3.2. Limitations • ABS does not help the user in conflict management i.e. there is no way the user can document the conflicts detected in the collision detection tests he runs. This incapability of ABS is one of the main limitations of this tool, as when the project participants sit down for the coordination meeting, the developer has to pan the drawings all over again to check for the conflicts and this tends to be time consuming. • The conflicts detected are represented in the 2D drawings and not in the 3D regenerated model and hence, in a complex system, it's very difficult to locate all the conflicts. The software does not produce any kind of documented file, but only represents the conflicts in the floor level among the systems developed in the floor level. For example, in the UBC Chem Bio Project that was undertaken as a case study in the work by Tabeesh and Staub-French (Tabeesh and Staub-French, 2005), there are many conflicts that were left unreported due to this. 51 V I 11W \ SMO | . 11 Ki j . « B 4 „ _, ri x Figure 4.3: Post rendered image in A B S after running collision detection tool As seen in the above image which has been captured after running the collision detection tool of ABS, there isn't any clear idea of the number of interferences in the floor level as the color coding of the interference detection tool maybe similar to those of the components installed in the floor level. Although, in their study, they determined interferences, due to the incapability of the tool many of them went unreported as seen below: 52 f3' Autodesk Building Systems 2006 - [5th Floor Final File-June 10th] — - k j i s u i a tip Ne E.dit i5ew Insert Format MEP Common Window IFC-Utiity fclelp . e x «4 .ni <?} V * H <© »< Q s C • *S? « I *; k, 9 | j / /• / -. , a o v . . < c *: J -:.. •> # > ») V J . \ / .<•< /Layoutl (2)/Martin[BndgesJXLayoutl ( 3 ) / ® Scale: 9 6 . 0 0 0 0 0 0 * Standard ~ f ^ ' " f l f '<f*Z :Command: _3dpan Press ESC or ENTER to e x i t , or r i g h t - c l i c k to di s p l a y \ \ shortcut-menu. - Command: 2 4 4 5 5 . 7 3 , 1 4 8 1 0 4 . 0 . 0 0 SNAP G R I D | 0 R T H 0 P O L A R | 0 S N A P J 0 T R A C K D Y N L W T | M D D E L Elevation: + 0 . 0 0 1*8 $ a M rf' * Figure 4.4: A Typical Unreported Conflict in ABS Although, ABS does not detect spatial conflicts, the rendering and regeneration it does for the hard conflicts is a strain for the eyes of the user as he has to pan through the entire system to determine the interferences and also look through the 3 D Model of the floor level simultaneously to check for the interferences all along the height of the floor level. This becomes a tedious process for the user and it is impossible for the user to document these interferences. ABS only recognizes the hard conflicts (i.e. physical interferences between the objects) and doesn't have any built-in functionality to analyze constraints such as access space, installation space or clearance which form most of the constraints in the MEP Systems. This limitation of ABS was the main point of departure for me to look into some other tool that can be used to help us in a better conflict management system (NavisWorks™). In further sections, I have demonstrated how NavisWorks surpasses ABS as a better conflict detection and management tool, by reviewing the case study i.e. UBC Chem Bio Project done by Tabeesh and Staub-French (Tabesh and Staub-French, 2005) using NavisWorks and undertaking constraint based checking for the conflicts in the entire project. My analysis of the case study using NavisWorks has been discussed in depth in the next chapter. 53 • For the soft conflicts, all work is based on human interpretations and professional advice. • Having the interference / collision detection tool enabled always results in performance problems when we are working with large complex drawings in ABS. • In ABS for the plumbing module, interference detection works only with equipment and fixtures; however, it can be helpful when working in conjunction with the mechanical and electrical modules. 4.4. NavisWorks JetStream™ (NavisWorks) (executed from NavisWorks Users Manual) 4.4.1. Introduction NavisWorks offers universal access to view and walkthrough 3D CAD models in real-time; with interactive visualization and interference checking regardless of file size or format. A virtual building is created from numerous 3D CAD files, thus enabling true collaboration between the design team even if they are not on compatible CAD systems. Effective 3 D design review with NavisWorks contributes to complete, accurate and coordinated production information so that projects finish on time and within budget. Design issues and interference errors can quickly be identified and rectified before work commences on site thus avoiding the expense of delay and reworking. Some of the features of NavisWorks are as below: a) Clash Detective™: The Clash Detective plugin checks your model and shows you any areas where items interfere or "clash" with each other. Like all plugins, the Clash Detective is a dockable tabbed control bar accessed through the Tools menu. From the Clash Detective control bar you can set up the rules and options for your clash tests, view the results, sort them and produce a report as a text file or in HTML or XML formats. b) TimeLiner™: The TimeLiner™ plug-in adds 4D schedule simulation to NavisWorks™. TimeLiner™ imports schedules from a variety of sources; allows you to connect objects in the model with tasks in the schedule; simulate the schedule showing the effects on the model, including planned against actual schedules; and export images and animations based on the results of the simulation. TimeLiner™ will automatically update the simulation if the model or schedule changes. This tool acts as your visualization module with respect to your project schedule which you may draft in Microsoft Project™ or any other Scheduling Software. c) Presenter™: The Presenter™ plug-in enables you to set up materials and lights in your scene and render it with more realism and effects. Using the Presenter™, you can edit pre-defined materials and apply them to items in the scene, add lights to the scene and set up 54 rules for applying the materials to other files in the same project set up with the same parameters. You can define and apply your materials and lights to a model and save the settings into a NavisWorks .nwf file so that as the model is updated, the materials and lights remain the same. Materials can also be brought through from CAD applications via the .3DS, .dwg and .dgn file formats, or by exporting from 3D Studio Viz or Max. The Features of Presenter™ include rendering a scene, applying various kinds of materials to the components in the drawing, lighting effects, rendering backgrounds, texture spaces etc. d) Publisher™: NavisWorks Roamer™ has an optional plug-in called NavisWorks Publisher™ that enables you to take a snapshot of the model at a certain time for issuing for use by other members of the design team, who perhaps are not CAD users, but who have a need to view the 3D model. e) Freedom™: NavisWorks Freedom JS™ is a cut down free version of NavisWorks Roamer™. It is designed to work with NavisWorks Publisher™ by allowing you to distribute published .nwd files to your clients and other non-CAD users for free and easy viewing of your models. Simply publish the .nwd file, give them Freedom™, and let them walk around your model. 4.4.2. Introduction to Clash Detection Mechanism The Clash Detective plugin checks your model and shows you any areas where items interfere or "clash" with each other. Like all plugins, the Clash Detective is a dockable tabbed control bar accessed through the Tools menu. From the Clash Detective control bar you can set up the rules and options for your clash tests, view the results, sort them and produce a report as a text file or in HTML or XML formats. A clash test is a configuration of options, rules and selections used in checking for clashes in a model. These are useful if you have set tests for your model and need to run them as a batch. You can create a number of different clash tests for a model and save them in a NavisWorks .nwffile for checking with updated models at a later date. General clash tests that you are required to run on all projects can be set up once, exported and then re-used on subsequent projects. Such tests may be specific to your industry or company; for example, you may always use a particular diameter piping which requires insulating. You could therefore set up a test, which selects all of this piping in the scene and clash test it against the rest of the model to ensure a specific clearance around it is maintained. Managing a series of clash tests can get complicated, especially if you have a whole set of different layers you want to clash 55 separately. Clash Detective is designed to help you control these clash tests and leave an audit trail of clashes throughout the life of the project. One simple but time-saving way it does this is by remembering the names of clashes throughout the project's life so you don't have to go through each clash every time you do a test to figure out whether it's a new clash or one you have already seen. Clash Detective also allows you to assign a status to a clash and can update this status automatically, informing you of the current state of the clashes in the model. You can set up a batch of clash tests that you could run overnight, every night and for each test, choose the items to clash against, along with the options for the test. Setting up and running a clash test: • Select a previously run test from a batch, or start a new test • Set the rules for the test. • Select the required items to be included in the test and set the test type options. • View the results. • Produce a clash report. 4.4.3. Definitions / Terminology • Clash Status: Each clash has a current status associated with it and each status has a colored icon to identify them. This status is updated automatically by Clash Detective or can be manually overridden if desired. The statuses are as follows: o New: a clash found for the first time in the current run of the test. o Active: a clash found in a previous run of the test and not resolved. o Approved: a clash previously found and approved by someone. o Resolved: a clash found in a previous run of the test and not in the current run of the test. It is therefore assumed to be resolved. o Old: any clash in an "old" test. The icons still have the code of the status from the previous run, but this is a reminder to say that the current test is old. If the status is changed to Approved, Clash Detective takes the user currently logged on as the person who approved it. Enabling hyperlinks will show clash results using the relevant status icon. • Clash Test Status: A clash test can have one of 4 statuses-o New indicates a clash test that has not yet been run with the current model. 56 o Done indicates a clash test that has been successfully run with the latest version of the model. o Old indicates a clash test that has been altered in some way since being set up. This might include changing an option, or having loaded the latest revision of the model. o Partial indicates a clash test that has been interrupted during execution. Results are available up to the point of interruption. Clearance Clash: A clash in which the geometry of item 1 may or may not intersect that of item 2, but comes within a distance of less than the set tolerance. Hard Clash: A clash in which the geometry of item 1 intersects that of item 2 by a distance of more than the set tolerance. Duplicate Clash: A clash in which the geometry of item 1 is the same as that of item 2, located within a distance of between zero and the set tolerance. A tolerance of zero would therefore only detect duplicate geometry in exactly the same location. Intersection Method: A standard Hard clash test type applies a Normal Intersection Method, which sets the clash test to check for intersections between any of the triangles defining the two items being tested (remember all NavisWorks geometry is composed of triangles). This may miss clashes between items where none of the triangles intersect. For example, two pipes that are exactly parallel and overlap each other slightly at their ends. The pipes intersect, yet none of the triangles that define their geometry do and so this clash would be missed using the standard Hard clash test type. However, choosing Hard (Conservative) reports all pairs of items, which might clash. This may give false positives in the results, but it is a more thorough and safer clash detection method. Severity: For hard clashes, the severity of a clash depends on the intersection of the two items intersecting. Hard clashes are recorded as a negative distance. The more negative the distance, the more severe the clash. Hard clash severity depends on whether the Conservative or Normal Intersection Method has been applied. If Normal, the greatest penetration between a pair of triangles is measured. If Conservative, the greatest penetration of space around one item into the space around another is measured. For clearance clashes, the severity depends on how close one item invades the distance required around the second. For example, an item coming within 3mm is more severe than an item coming within 5mm of the other. For duplicate clashes, the severity depends on how close one item is to the other. When the distance between them is zero, it is more likely that 57 this is duplicate geometry, where as items that are further apart are more likely to be different objects and therefore have a lesser severity. • Tolerance: The Tolerance controls the severity of the clashes reported and the ability to filter out negligible clashes, which can be assumed to be worked around on site. Tolerance is used for Hard, Clearance and Duplicate types of clash test. Any clash found that is within this tolerance will be reported, whereas clashes outside of this tolerance will be ignored. So for Hard clashes, a clash with a severity of between zero and the tolerance value will be ignored, whereas for Clearance clashes, a clash with a severity of more than the tolerance value will be ignored as it is further away than the distance required. Similarly, a Duplicate clash with a severity of more than the tolerance value will be ignored as it is likely to be a separate, yet identical piece of geometry. 4.4.4. Clash Batches 4.4.4.1. Introduction to Clash Batches The Batch tab of the Clash Detective control bar is used to manage your clash tests and results. You can set up as many tests as you like in a batch and save them into the NavisWorks .nwffile so that on opening it up again the tests can be re-run with the new model revision. B a t c h | O p t i o n s | S e l e c t J R e s u l t s | R e p o r t ) r T e s t s — — — — N a m e e l e c t r i c a l & m e c h a n i c a l T e s t 1 T e s t 2 1 S t a t u s O l d N ft '.••! N e w j C l a s h e s 4 0 9 • O I N e 4 0 : O • X U p d a t e A d d 1 D e l e t e | C o m p a c t | C l e a n C l e a r A l l [ Figure 4.5: Batch Window in NavisWorks To run a clash test, either: • Click on Update to run all of the tests in the batch. Or • Select an existing test to run on its own, switch to the Select tab and click Start. 58 4.4.4.2. Managing batches of clash tests • Click Add to append a new test to the current batch. • Click Delete to delete the currently selected test from the batch. • Click Compact to delete all clash results with a status of resolved from the test in order to create a smaller file. • Click Clean to reset all tests so that they are as if you had not yet run them. In other words, this will make their test status new. • Click Clear All to remove all tests from the batch in order to start from scratch. • You can rename a test by selecting it and either pressing F2, or by clicking again on the highlighted text. 4.4.4.3. Merging clash tests from multiple files Merge the files using File, Merge. See the File Management, Merging Files section of the NavisWorks Roamer user guide for more information. All of the clash test data will be combined, whilst any duplicate geometry from the files will not be loaded. 4.4.4.4. Importing clash tests Clash tests can be imported into NavisWorks Clash Detective to set up pre-defined, generic clash tests. If the clash test to be imported contains a search set as one of the clash selections, then the search set will also be imported along with all other test rules, options and selection information. To import a clash test: • From the File menu, choose Import, Clash Test XML... The Import dialog is displayed: 59 File name: Files of type: jXML f.xml I™* Open as read-only Figure 4.6: Import Dialog Box in NavisWorks • Locate and Open the .xml file to import the clash test information, or click Cancel to return to NavisWorks. 4.4.4.5. Exporting clash tests Tests can be set up to clash items based on generic properties, including direct property selection in the left and right clash selection trees, or using pre-defined search sets. For example, you may have saved a search set that finds all pipes of a specific size, named "100mm Pipes". Your test then clashes all 100mm Pipes against the entire model. Exporting this clash test will enable you to import it into another model, which will automatically set up a clash test between 100mm Pipes and the entire model. Any clash tests that are based on explicit selections will not be exported. For example, clashing one layer against another is not a valid test for exporting. To achieve this you will need to use the Find Items dialog to search for each layer based on a specific property (e.g. Item, Name). These searches can then be saved as Search Sets and finally selected in the Left and Right selection trees in Clash Detective. One may also select all loaded files in the Left or Right selection tree and Clash Detective will treat this as selecting the entire model. Multiple generic tests can be set up as a batch and exported for use by other Clash Detective users or by you on other projects. 60 To export a clash test: • Having set up your implicit clash tests, from the File menu, choose Export, Clash Test X M L . . . The Export dialog is displayed: File name: | snowmobile, xml Save as type: ]XML(".xml) Save Cancel Figure 4.7: Export Dialog Box in NavisWorks • Enter a new file name and location, if you wish to change from those suggested. • Click Save to export the .xml file, or click Cancel to return to NavisWorks. 4.4.4.6. Creating custom clash tests Exported clash tests can be used as a basis to define custom clash tests. If you have a common set of clash tests that you reuse on multiple projects, you can turn them into a custom clash test. Once installed as a custom clash test, the entire batch of tests can be selected and run directly from the Select tab. The results from all tests in the batch are combined and presented as the results of the custom clash test. The name of each test in the batch is displayed in the Description field of the results. Custom clash tests are an excellent way to roll out a standardized set of tests across an organization. They allow the expertise of "power" users to be reused by everyone. Finally, they can be seen as a way of implementing object intelligence. For example, a custom clash test could be written that checked for compliance with a local building code based on object information and properties defined in a particular C A D system. 61 To define a custom clash test: • Export your clash tests to an XML file. The name of the file is used as the default name of the custom test. • If desired, change the name of the custom test by editing the XML file directly. The top level element in the XML file is called "batchtest". The name of the custom test as displayed to the user is defined by the "name" attribute. The name of the custom test as saved in a file is defined by the "internal name" attribute. • To install the custom test, copy the exported XML file to the custom_clash_tests subdirectory of one of the NavisWorks search directories. Clash Detective searches these directories on startup looking for custom tests. • To use the custom test select it from the Test Type drop down on the Select tab. And press Start. All other options and rules are specified by the custom test. 4.4.5. Clash Rules 4.4.5.1. Introduction to Clash Rules The Rules tab of the Clash Detective control bar allows you to define and customize ignore rules to be applied to the clash test. The Rules Tab looks as below: Batch Rules 1 Select | Results) Report | Ignore Clashes Between [ l i tems in same layer 1 litems in same group/block/cell !~~~]l terns in same file TJ Items in same composite object 1 litems in previously found pair of composite objects f litems with coincident snap points New f d" 1 Figure 4.8: Rules Window in NavisWorks 62 4.4.5.2. Setting Clash Rules The Ignore Clashes Between box enables you to select "rules" that reduce the number of clash results by ignoring certain combinations of clashing items. The following rules are built-in: • If Items in same layer is checked, any items found clashing that are in the same layer are not reported in the results. • If Items in same group/block/cell is checked, any items found clashing that are in the same group (or inserted block) are not reported in the results. • If Items in same file is checked, any items found clashing that are in the same file (either externally referenced or appended) are not reported in the results. • If Items in same composite object is checked, any items found clashing that are part of the same composite object (an item composed of multiple parts of geometry) are not reported in the results. • If Items in previously found pair of composite objects is checked, any items found clashing that are part of composite objects (items composed of multiple parts of geometry) that have previously been reported in the test are not reported in the results. • If Items with coincident snap points is checked, any items found clashing that have snap points that coincide are not reported in the results. This can be particularly useful for pipe runs made from cylinders. • If Items in the same AutoPlant Component is checked, any items found clashing that are contained within the same AutoPlant component are not reported in the results. • If Connected AutoPlant Components is checked, any items found clashing that are in connected AutoPlant components are not reported in the results. 4.4.5.3. Adding Custom Rules NavisWorks Clash Detective provides a number of templates which you can customize to create your own ignore rules. To add a new ignore rule: • Click the New button. The Rules Editor dialog is displayed: 63 Rules Editor Rule name 211 New Rule Rule Templates Items in same layer Items in same group/block/cell Items in same file Items in same composite object Items in previously found pair of composite objects Items with coincident snap points Insulation Thickness Same Property Value Same Selection Set Specified Selection Sets Rule description (click on an underlined value to edit it) Figure 4.9: Rules Editor Window in NavisWorks Enter a new name for your rule. From the Rule Templates list, choose a template to customize. The following templates are built in: a) Insulation Thickness. This rule is to be used with a Clearance test and will ignore any items found clashing where the clearance is greater than the insulation thickness. If you have a pipe requiring a specific thickness of insulation, then you may want to carry out a clearance test on that pipe, setting the clearance tolerance to the required insulation thickness. This would identify any areas where there is not enough clearance around the pipe to install the insulation. If you have various pipes, all requiring different thicknesses of insulation then rather than setting up a separate clearance test for each thickness, you can set up one test with the greatest necessary tolerance, i.e. assume all pipes require the maximum thickness of insulation. This rule can then be applied to ignore any clashes that are falsely identified, as their actual insulation thickness is less than the maximum clearance used. The diagram below for an example depicts where this ignore rule would be applied: 64 t t 1 2 c F Pipe 1 has insulation thickness t and C is the maximum clearance (thickest insulation) required anywhere in the current model. Any items (2) that come within the range of t to C will not be reported in the results. b) Same Property Value. This rule will ignore clashing items that share a specific property. c) Same Selection Set. This rule will ignore clashing items that are in the same specified Selection Set. d) Specified Selection Sets. This rule will ignore clashing items where each item is in a specified Selection Set. • In the Rule Description box, click on each of the underlined values to define your custom rule. The customizable values available with the built in templates are: a) Name. Use the name of the category or property as it is displayed in the interface (recommended). You can also choose Internal Name which is that accessed via the API (for advanced use only). b) '<category>'. Choose from the available list, which category the property you wish to define is in. Only the categories that are contained in the scene are available in the drop down. c) '<property>'. Choose from the available list, which property you wish to define. Again, only the properties in the scene within the chosen category will be available. d) the Last Object. Search for the defined property on the specified selection. The Last Object is the default, though you can also choose from Any Parent, a Model, a Layer, or the Geometry. e) '<set>'. Choose from the available list, which Selection Set you require to define the rule. Only the pre-defined Selection and Search Sets are available in the drop down. • Click OK to add the new ignore rule, or Cancel to return to NavisWorks. 4.4.5.4. Editing Clash Rules • Choose the ignore rule you wish to edit. • Click the Edit button. • Rename the rule if you wish to change it from its current name. • Choose another Rule Template if you wish to change it from the current template. • In the Rule Description box, click on each of the underlined values to redefine your custom rule. • Click OK to save the changes you've made to the rule, or click Cancel to return to NavisWorks. 4.4.5.5. Deleting Clash Rules • Choose the ignore rule you wish to delete. • Click the Delete button to delete the clash rule. 66 4.4.6. Selecting Items for Clash 4.4.6.1. A n Overview The Select tab of the Clash Detective control bar allows you to refine your clash test by only testing sets of items at a time, rather than the whole model against itself. This will produce faster and more sensible results. You choose two sets of items to test against each other using selection trees, which are exactly the same tabs as those in Roamer's selection tree control bar. The Select tab is also where you set the test type and tolerance and where you run a single test from. Batch | Rules Select j Results | Report | • r~ I 1 L e f t Hight— Standard I - Self Intersect Standard f - Self Intersect Select Current Select Current I 1 Run Type: Tolerance (m)' |Hard (10.000000 Start Found: JQ Figure 4.10: Select Window in NavisWorks 4.4.6.2. Selecting items for a clash test a) There are two identical boxes in this tab called Left and Right. These boxes represent two sets of items that will be tested against each other during the clash test and you need to select items in each. You can select the items by choosing a tab from the selection tree and manually selecting items from the tree hierarchies. Any selection sets in the scene are 67 also included on a tab, which is a quick and useful method of setting up items across sessions. b) You can also transfer the current selection to one of the boxes by selecting items in the usual way in the main navigation window and/or selection tree and clicking the appropriate Select Current button. c) Check the appropriate Self Intersect check box if you want that set to test for self-intersection, as well as intersection against the other set. 4.4.6.3. Setting the clash test type and tolerance options There are four default clash test types for you to choose from: • Hard. Choose this option if you wish the clash test to detect actual intersections between geometry. • Hard (Conservative). This option performs the same clash test as Hard; however it '' additionally applies a conservative intersection method. This clash test type is only available when in Developer profile. See the Interface, Profiles section of the Roamer book for more information on user profiles. • Clearance. Choose this option if you wish the clash test to detect for geometry within a set distance from other geometry. You might use this type of clash when pipes need to have space for insulation around them, for example. Clearance clashes are not the same as "soft" clashes. Clearance clashes detect for static geometry coming within a distance of other geometry, whereas soft clashes detect potential clashes between moving components. NavisWorks Clash Detective does not currently support soft clash checking. • Duplicates. Choose this option if you wish the clash test to detect for duplicate geometry. You might use this type of clash test to check a model against itself to ensure the same part has not been drawn, or referenced twice, for example. To select the clash test options: • From the Run, Type drop down, choose the clash test type you wish to run. Any custom clash tests that have been defined appear at the end of the list. • Enter the Tolerance required, which will be in metric units. 68 4.4.6.4. Running The Clash Test Once the left and right sets are selected and the clash type and tolerance defined, click on Start to start the test running. The Found box shows how many clashes have been found so far during this test. The progress bar shows how far through the test Clash Detective has got. If you wish to stop the test at any time, press the Cancel button and all clashes found up until the interrupt will be reported and the test will be saved with a Partial status. 4.4.7. Clash Results 4.4.7.1. An Overview The Results tab of the Clash Detective control bar enables you to interactively view the clashes found. On the left is a list of clashes, numbered and sorted by severity. The list also shows the status, the distance, the clash point, date found and, if the clash has been approved, who approved it and when it was approved. Batch | Options | Select [E^Sl Report | Name Status Dista Found • Clashl • Clash2 • Clash3 • Clash4 • Clash5 • Id • Id • Id • Id • Id • ClashG Old • Clash7 Old -0.066m -0.042m -0.015m -0.015m -0.015m -0.015m -0.012m 10:00:04 10:00:04 10:00:04 10:00:04 10:00:04 10:00:04 10:00:04 07/0 07/0 07/0 07/0 07/0 07/0 07/0 li . n u . i . n n u ^ n . n n . n ji m .'fi I tern 1-———— - — • — -Item Name: WALL_249 ZI Item Type: PolyFace Mesh - | gatehouse, nwd M BR ICK_FACING WALL_249 i m W A L L _ 2 4 9 LLJ : i R Highlight BAND Select r Item 2 Display • Select Filter • A u t o Reveal 0 A u t o Zoom H S a v e Viewpoint • Highlight All • Dim Other • Hide Other Item Name: WALL_269 * 1 Item Type: PolyFace Mesh j gatehouse, nwd M C A V I T Y _ C L O S E R _ V E F k & WALL_269 B-ffiP W A L L _ 2 6 9 LiJ i W Highlight Select Figure 4.u: Results Window in NavisWorks 69 .2. Reviewing Clash Results Click on a clash to highlight both clashing items in the main navigation window. The "Item 1" and "Item 2" boxes show the Smart Tag properties relating to each item in the clash and also the path through the standard selection tree from the root to the geometry of the item. Click on the clashes name or press f2, if you want to rename the clash. This name will be saved and remembered for future tests. To manually change the status, select a new clash status from the drop down list. To enter notes about the clash for others to review, right click on the clash and choose Add Comment from the context menu. The Add Comment dialog will appear to allow you to enter your comment. Select the display options you wish to apply: • Check Select Filter if you want to select an item in the main navigation window and show only those clashes that involve that selected item. • Check Auto Reveal if you want NavisWorks to attempt to temporarily hide anything obstructing the clashing items so that you can see the clash when zooming in on it, without having to move location. • Check Auto Zoom if you want to automatically zoom in on the selected clash. Unchecking this box allows you to keep the main viewpoint static while flicking through the clashes one by one. • Check Save Viewpoint if you want to store the current viewpoint with the result. This allows you to tailor the viewpoint for a clash result. It also enables redlining to be stored with a clash result. Once redlining has been added, subsequent changes to the viewpoint due to navigation will not be saved. In order to save a different viewpoint, the redlining must first be removed using the redline Erase tool. • Check Highlight All if you want to highlight all the clashes found in the main navigation window, in the color of their status. • Check Dim other if you want to turn all items not involved in a clash to gray. • Check Hide other if you want to hide all items not involved in a clash in order to focus better on the clashing items. 70 • Check the Highlight check box to override the color of the item in the main navigation window with the color of the status of the selected clash. • Click Select to select a clashing item in the main navigation window. If a selection color is set (by default blue), this overrides the Highlight option, which allows you to highlight the item, in the color of its status. 4.4.8. Clash Reports 4.4.8.1. A n Overview The Report tab of the Clash Detective control bar is used to write reports containing details of all the clash results found in the current test. You can write a text file, an html or xml file containing jpegs of the viewpoints of the clashes or simply save the clash results as a list of viewpoints for review by a NavisWorks user without the Clash Detective plugin. B a t c h | R u l e s | S e l e c t | Resu l t s Repor t | Repo r t T y p e j Current test ^ | - Con ten t s - Inc lude C l a s h e s [yjlS ummary W N e w @ C l a s h Point S3 A c t i v e [v ' iDate F o u n d [y<] A p p r o v e d (yfl D ate A p p r o v e d Iv*] R e s o l v e d [ y JApp roved By • Old V : Layer N a m e [yOltem P a t h fV)l tem ID [«•] S tatus [ ^ D i s t a n c e Descr ip t ion fy1] Commen ts [y]Smart T a g s Repo r t Format | H T M L H W r i t e Repor t Figure 4.12: Report Window in NavisWorks 4.4.8.2. Reporting Clash Results • In the Contents box select all the information you want to appear in the report for each clash result. This can include Smart Tag properties relating to the items involved in the clash, how to find them in the standard selection tree from root to geometry, clash status and so on. 71 • Check those clashes in the Include Clashes box to select which clashes you want to include in the report based on status. • Select the type of report from the Report Type drop down list: o Current Test creates a single file for the current test. o All Tests (combined) will create a single file containing all results from all tests o All Tests (separate) will create a separate file for each test containing all results, o Select the format of the report from the Report Format drop down list: o X M L will create an .xml file containing all the clashes and a jpeg of their viewpoints alongside their details. On choosing this option, you will need to select or create a folder for the files and enter a name for the xml file. o HTML will create an .html file containing all the clashes and a jpeg of their viewpoints alongside their details. On choosing this option, you will need to select or create a folder for the files and enter a name for the html file. To customize the appearance or layout of the html file, you will need to edit the 1 clash_report_html_lang.xsl file, where lang is a code representing your language. The installed file is located in the s t y l e s h e e t s subdirectory of the NavisWorks install directory. You can copy the edited file to the stylesheets subdirectory of any of the NavisWorks search directories. o Text will create a .txt file containing all the clash details and the location of a jpeg of each clash. On choosing this option, you will need to select or create a folder for the files and enter a name for the txt file. o As viewpoints will create a folder in the saved Viewpoints control bar, called the name of the test. Each clash is saved as a viewpoint in this folder, with a comment attached containing the clash result details. • Click the Write Report button to write the report. 4.4.9. Discussion • On the face value, NavisWorks appears to be a more handy conflict detection tool then ABS, as it gives the user a more detailed outlook on the conflicts detected in the drawings. • NavisWorks™ also enables the user to check the model for the different types of modeling and design constraints, which is not available with ABS. This is in addition to the normal physical interferences that one can determine by running the simple Hard Clash Test with Zero Tolerance. 72 The multiple functionalities such as TimeLiner , Publisher , Roamer and Freedom™ of NavisWorks gives the project participants a detailed retrospective of the schedule, work progress and productivity of the project, and these help in giving the project participants a better analysis of the on goings. NavisWorks is more user friendly then ABS and thus is getting more popular in the industry for conflict detection. NavisWorks enables the user to save all the clash results of the tests run on the project by using the write report tool which helps in conflict management and reduces the time when the project participants sit down for the MEP Coordination meeting and thus helps in dedicating more time for resolving the conflicts. Another major advantage of using NavisWorks is the option of using .NWF extension for the drawing files. .NWF basically is a pointer variable and when one needs to incorporate the solution proposed in the meeting and check the whether this solution is appropriate for the clash. The user just has to open the AutoCAD file of the drawing and make the changes there and when he reopens the .NWF File of the drawing, all the changes made to the original drawing are incorporated and thus if the solution proposed was correct then when the user runs the clash test, he/she does not see the conflict any more and if it was the wrong solution then the clash is displayed. This speeds up the entire Conflict Resolution Process and thus in turn speeds up the MEP Coordination Process. Although there is lot of advantages of using this tool, I would like cite some limitations I found with this tool too. For example, when one models a clearance constraint for a specific side, say horizontal, then the results show the conflicts within the whole zone mentioned in the tolerance. Also, NavisWorks is incapable in modeling positioning related constraints. This will be more explained in detail in the next chapter wherein I have done the review of the 3D Models of UBC Chem Bio Project using NavisWorks. To conclude, the advantages of using this tool definitely outdo the disadvantages and the same will be understood in more detail in the Chapter 5 wherein I will also compare this tool with ABS in more detail using the results of the case study by Tabesh and Staub-French (2005) on the UBC Chem Bio Project (wherein they had used ABS as the tool for conflict detection). 73 Chapter 5: Review of UBC Chem Bio Project using NavisWorks 5.1. Introduction Past research on MEP Coordination collected their knowledge by observing coordination meetings, interviewing the project participants or by conducting a survey. There has not been much that focused on any one particular project and documented the conflicts and coordination constraints found in that project. The study of University of British Columbia (UBC)'s Chemical Biological Engineering Building Project by Tabesh and Staub-French (2005) was one of the research efforts that made use of 3D Modeling Techniques for the design and coordination of the Mechanical,Electrical and Plumbing (MEP) Systems. 3D modeling and collaboration of the MEP systems which is now being slowly implemented in the industry helps project participants to overcome the limitations of the conventional 2D MEP coordination procedure. Currently many in the industry use Autodesk® Building Systems (ABS) which is an extended application of AutoCAD for developing the 3D Models of the MEP Systems. ABS also has a function for interference detection, which enables the modeler to check for any physical interference in the assembled components in the project. ABS can be used only to detect the physical interferences in the model and cannot detect any conflict due to clearance or any other design and modeling related constraint: Tabesh and Staub-French (2005) documented the physical conflicts/interferences using ABS and the design and modeling constraints pertaining to the MEP Coordination Process for the UBC Chem-Bio Project. They also classified these constraints based on the Knowledge Attributes defined by Tatum and Korman (2001) and in addition to that also defined some knowledge attributes of their own in their study. However they did not correlate the identified conflicts with the constraints, nor did they do constraint based conflict detection of the assembled MEP Systems for the project. My review on the UBC Chem Bio Project which has been discussed in this section focuses on the following points: 74 • Check for the conflicts in the UBC Chem Bio Project using robust conflict detection tool, in this case NavisWorks Clash Detective. This includes checking for physical conflicts and also constraint based analysis for conflicts (e.g.: clearance based constraints for MEP Systems). • Classify the conflicts identified in UBC Chem Bio Project with respect to the type they represent using Korman's.Classification Framework (2001) i.e. actual, extended, future, temporal and functional types of conflicts. • Classify the constraints that govern the MEP Coordination Process with the types of conflicts they result in. 5.2. Case Background Tabesh and Staub-French (2005) documented an on-site project using this 3D design and coordination for MEP systems. The project under their study was the Chemical and Biological Engineering Building, which was being constructed on the campus of the University of British Columbia (UBC). Figure 5.1 shows the 3D Model of Chemical and Biological Engineering Building Project. This facility provides a variety of teaching and research spaces for the study of biological, chemical, environmental and process engineering at UBC. The project budget was approximately $38 Million and the construction schedule was 13 months. The 123,000 Square Feet building includes high-head laboratories, teaching/research laboratories, large lecture theatres; offices, seminar rooms, project rooms, undergraduate facilities; and shops, storage and support rooms. These spaces were been grouped for functional and adjacency reasons into two distinct structures: Laboratories, offices and lecture theatres have been grouped in a six storey structure. The high-head laboratories, attendant support spaces and workshops are housed in a low-rise, ground-related structure for service access and structural loading reasons. 75 Figure 5.1: 3D Model of Chemical and Biological Engineering Building Project (Source: Tabesh and Staub-French, 2005) The building systems of this project were complex and accounted for a large part of the total project cost. Tabesh and Staub-French (2005) modeled and coordinated a variety of building systems in 3D, including architectural, structural, mechanical, electrical, and plumbing systems, in support of the MEP coordination process. This provided a unique opportunity to collect specific and detailed MEP coordination knowledge, since there was an active involvement in the 3D coordination process rather than observing the process from the periphery. This was essential to learn what actually happens on the site during the MEP Coordination Process to gain more knowledge about the same. Tabesh and Staub-French developed detailed 3D models of all the building systems in several critical spaces and used Autodesk Building Systems™ software (ABS), because the architect and the consultants had already developed their 2D drawings in AutoCAD and because ABS offers an integrated MEP - Architectural application. In addition, ABS provides much of the engineering data needed in a library of standard predefined objects (e.g. walls, doors, windows, ducts, pumps, valves, etc.). In this process, by analyzing the composite model, the MEP coordinator can identify physical interferences and non-compliance with different design, construction and operation constraints. In addition, the model can provide separate drawings and design views of the MEP systems by 76 different specialty contractors, during and after the coordination process. Figure 5.2 illustrates an integrated view of a typical lab in the fifth floor which was an area where Tabesh and Staub-French (2005) more concentrated their analysis on. Figure 5.2: Integrated 3D model of a typical lab on the fifth floor (Source: Tabesh and Staub-French, 2005) Tabesh and Staub-French (2005) in their study modeled approximately 800 m2of laboratory and corridor space. They identified 25 design errors, omissions, and inconsistencies and 25 MEP coordination issues. In addition to this they also classified the MEP coordination knowledge (design and modeling constraints that governed the MEP systems) they acquired in the project based on the Domains of Classification viz; Construction, Operation and Maintenance and Design. 5.2.1. Conflicts Detected by Autodesk® Building Systems (ABS) In their research, Tabesh and Staub-French (2005) used ABS for detecting conflicts and below is the list of conflicts identified in the work either in the modeling stage or in the conflict detection stage by floor levels: 77 Design/Consultant related Issues: These are the types of issues raised and addressed, which does concern the consultant body and most probably requires formal RFI and in some cases, changes in the drawings and/or designs. 5 t h Floor Typical Lab: th th 1. Slab opening on 6 floor slab, right in the Electrical Room and the 5 floor slab extra opening. 2. The floor drain and the related sanitary line located in Room 516. 3. Missing size on the exhaust duct in 508 Lab. 4. The change in the Room 512 riser and layout of the wall. 5. The resulting changes in Room 512 regarding the sink CA and gas pipe. 6. Sanitary line and stack in Room 508. 7. The cup sinks and their sanitary drains. 8. The ventilation of acid neutralizers (there is no ventilation). 9. Sizes of the Sanitary Pipes for fume-hood and sinks. 10. Branching at either sides of the wall, or one side. 11. Opening in the concrete block wall adjacent to riser, to pass the conduits. 12. The location of the diffuser in the 518 lab. 6th Floor Corridor: 1. Chilled Water/Heat Recovery line. 2. Floating ceiling elevation on the bridge. 3. Cable tray clearance and layout. 4. Finished floor heights and the sloping roof slab. 5. Arrangement of lighting fixtures. 6. The exact positioning of roof drains on the roof. 7. The layout of storm-water drain pipe and stack. Main and 2 n d Floors Corridor: 1. The rain-storm water run discontinued at the lower floor. 2. The cable tray size and layout in the main floor. 3. Slab opening dimensions and trimming the concrete beam. 4. The cable tray clearance in the corridor of High-head Lab. 5. The difference in elevation between architectural and structural drawings. 6. Missing sizes in the plumbing pipes. 78 M E P Coordination-Related issues/lessons learned: These are the issues that were raised and addressed that are of concern to the MEP trades and should serve as a warning to avoid future conflicts. Obviously all of the previous section should also be considered by the MEP trades, in addition to the following: 5 t h Floor Typical L a b : 1. The elevation of Main Supply Ducts and their connection to the diffusers. 2. The location of the Exhaust Duct in the Room 508, mounted at 2100 AFF. 3. The positioning and layout of the Supply Duct and the Fume Hood Air Valves in Room 518. 4. The elevation of the Return/Exhaust Duct running parallel to the windows in the labs. 5. The interference of the wall unit, and the Vent Stack in Room 508. 6. The elevation of exhaust ducts in 508 and 518 labs. 7. The order and offset dimension of pipes to leave the proper sleeves. 8. Compressed Air pipe running from Rooms 508 to 514. 9. Relative elevation of vent pipe from 512 to 508, & duct work in 508 and 514. th 10. 6 floor, floor drains in Room 508. 11. Compressed Air and Gas pipe to supply fume-hoods. 12. Proper elevation and layout of the conduits. 13. 5 degree turns in the conduit ending in the opening. 14. Elevation of the Gas pipe in Room 518 (avoid conduits). 15. The layout of the supply diffusers. 16. Supply duct layout in Room 512. 17. Relative elevation of sanitary waste pipe and ducts in the lab 518. 18. Layout, positioning and elevation of sanitary waist in 508. 6th Floor: 1. The arrangement & relative elevation of HWS & R in the corridor and bridge. 2. The proper layout and elevation for the other plumbing systems (Storm-Rain water, Domestic/Hot water systems). 3. The positioning & routing of the ducts relative to the corridor walls and slab. 4. The finished height in the labs and the service space less than indicated. M a i n and 2 n d Floor: 1. Paying attention to plumbing layout and elevation, since there are 4 different ceiling height elevations involved. 2. Positioning in the tight area in front of the elevator (works, but there is no room for mistakes). 79 3. Duct transitions, offsets, and elbows to maximize the usage of the space. Unresolved Issues: There were some conflicts which were identified in the study, which needed to be discussed or resolved by having meetings with the respective project participants and they are as below: 1. Fire Protection in the staircase (all floors). nd 2. Fire Protection in the corridor (Double Sprinklers) (2 floor). nd 3. Interference of the Conduits and the Wall-mounted fire protection pipes in 2 floor. th 4. The thickness of the wall containing the Rain/Storm stack in 6 floor. 5. The Location of diffuser in Rooms 512 and 518. 6. In the fifth floor, Vent line and stack near grid line 5 does not carry any size. th 7. The effect of the sloping roof slab in the 6 floor, on the service area in the labs. 5.2.2. Classification of Design and Modeling Constraints Tabesh and Staub-French (2005) identified the design and construction knowledge utilized to create a coordinated and constructible design. They classified this knowledge in a framework that associates the design and construction constraints that govern the modeling and coordination process with the knowledge domain, the domain context, and the specific modeling and coordination task. The goal was to formalize the MEP coordination knowledge collected to convey the context of the knowledge, represents the generality of the knowledge, enables reuse of the knowledge across multiple projects, and potentially supports computer-based implementation. Figure 5.3 shows the three dimensions of the framework developed to represent the design and construction constraints captured in their case study, which included the knowledge domain, the specific knowledge attributes, and the modeling and coordination tasks. The documented design and construction constraints are shown in Table 5.1. This framework builds on and extends the knowledge items identified by Korman et al. (2003). They also added some new attributes based on the facts of their case study, industry terminology, and the knowledge items used in other constructability frameworks. As they were more involved with the construction experts and therefore the developed knowledge attributes relate more to the construction domain. 80 a.- B 1 Know ledge Atnbutes t l k l l l l C M J ! 8 I 1 « i s I I % > I e I * J JS» \ . V I u I Figure 5.3: The three dimensions of the framework used to classify the design and construction knowledge (Source: Tabesh and Staub-French, 2005) 81 System Modeling and Coordination Constraints Knowledge Domain Tabesh's Knowledge Attribute Modeling & Goordinati • ;.oh Task Korman's Knowledge attribute 1 The ducts should maintain a minimum clearance from the adjacent walls and slabs Construction Tolerances Clearance 2 The ducts, needing the largest supports, should be positioned closer to the slab. Construction Productivity Routing Support System achanica 3 In case of external insulation of equipment, positioning should account for installation space. Construction Installation Space Positioning Insulation Installation Space S 4 The code implies the thickness of the duct's external insulation or internal lining Design Performance Insulation 5 The minimum standard radius of a round fitting elbow can not be less than its diameter. Operation Performance Detailing Construction Fabrication 6 It is better to install the ducts first, due to their size and inflexibility Construction Productivity Sequencing Sequence 7 U-shaped over passing creates air traps in pressure pipes; Avoid them Operation Performance 8 The RWD line can not run bellow the false-ceiling elevation Design Aesthetics Piping 9 In assigning space to pipes, should account for installing insulation. Construction Installation Space Routing Insulation Installation Space ocess 10 Pipes have higher maintenance frequency than ducts; therefore they should not be positioned above the ducts. Operation Access Access Spnnpnpp Cl. 11 RWD pipes should maintain a 1% minimum slope. Design Performance Slope b£ c 15 12 13 The minimum standard radius of a round fitting elbow can not be less than its diameter Operation Construction Performance F s n n r a l m n E 3 The code implies the thickness of the insulation around the pipe Design I Q U I lualiuil Performance Detailing Insulation CU 14 The placeholder used to hold a 4" vertical stack pipe in a wall, will need at least a 7" wall Construction Variance 15 The R W D routing should connect the vertical stacks of the adjacent floors Design Function Validating Design Function 16 A l l Waste/Sanitary Drain stacks have to be connected to the vent stacks going up from that floor. Design Performance System/Functio 17 The cable tray has to maintain a 60 cm horizontal clearance on one side to provide access to cables. -Operation Access Access Clearance M Construction Installation Space lectric; 18 The cable tray, has to maintain a 30 cm vertical clearance on top side to provide future accessibility to cables Operation Access Layout Access "Clearance UJ Construction Installation Space Ta 19 20 ble 5.1: The cable tray has to maintain a 15 cm vertical clearance zone anywhere on top side. The number of maximum 90 degree elbows from start to finish for a conduit is four Classification of Constraints based on Knowledge Domain. Attribute. Modeling Operation Operation & Coordinatio Safety Performance Performance a Tasks CTabe Routing sh and Staub-Clearance French. 2005) 5.2.3. Critique Tabesh and Staub-French (2005), did an excellent job in their study by taking the responsibility of modeling these MEP systems in 3D and determining the conflicts among the MEP Systems using a tool that will transfer the responsibility from the MEP Coordinator to the software under consideration (in this case, ABS). Their case study was limited in the following aspects: 1. In case of Conflict detection, ABS represents the conflicts in 2D and does not zoom to show each and every conflict, which makes it much more difficult to see and thus can result in many of the conflicts going unreported/undetected. 2. Tabesh and Staub-French (2005) identified 50 conflicts in their study. However, they failed to classify them based on the types of conflicts they represent (Korman's Classification Conflict Classification Framework, Korman et al. (2003)). 3. Tabesh and Staub-French (2005) classified the constraints they had found during the course of their work with respect to the knowledge domains, attributes and modeling and coordination tasks (See Table 5.1) which are key in MEP Coordination Process. However, they failed to correlate them with the interferences they identified and classify the constraints/conflicts based on the types of interferences. 4. ABS does not have the feature to check the 3D Models of the MEP systems for conflicts for the various governing design and modeling related constraints they identified in their study (See Table 5.1). Overseeing these constraint based conflicts at the modeling stage will chose them to be detected in the field when the entire system(s) is (are) ready to be installed / placed and will just add to the cost and delay the time frame of the project and result in the project going over the budget in terms of time and cost (discussed in Chapter 6). 5. ABS also does not have the functionality to check for the clearances (required for either installation of any component or for future maintenance operations) which are the most common constraints involved in MEP Systems. Therefore, they may have missed conflicts resulting from these constraints in their study. 6. When I was going through the 3 D Models of the project, I came across certain conflicts that were visible from naked eye but were overseen and unreported in their study. 83 5.3. Points of Departure for the Review From my critique on Tabesh and Staub-French's (2005) study and also the study by past researchers in this field, my review of the UBC Chem Bio Project focuses on the points that were missed in the past studies: • Review the assembled MEP Systems of UBC Chem Bio Project for physical interferences using NavisWorks. • Do a constraint based conflict detection testing for the assembled MEP Systems of UBC Chem Bio Project and check for the various active clashes in the project. • Analyze whether NavisWorks is a better Conflict Detection and Management Tool then ABS. • Classify the clashes identified in UBC Chem Bio Project with respect to the type they represent using Korman's Classification Framework (2001) i.e. actual, extended, future, temporal and functional types of conflicts. • Give a more comprehensive knowledge on the constraints that govern the MEP Systems by linking them to the type of interference(s) they generate. 5.4. M E P Design and Coordination Constraints As discussed in section 5.2.2, Tabesh and Staub-French (2005) identified 20 design and modeling related constraints and classified them with respect to the knowledge domain, the specific knowledge attributes, and the modeling and coordination tasks. In addition to these constraints, Tatum and Korman (2001) identified some constraints in their study which Tabesh and Staub-French failed to document or classify and they are as below: • Access Space required by personnel for valves is typically 12 in., depending on the type of valve • Required Clearance between Heating Water Supply and Heating Water Return Lines is 6 in. • Gravity Driven Wastewater drain lines should slope 1/8 in. per foot • Electrical conduit may rest on pipe racks that contractors attach to walls or hang from trapeze hangers • Insulation thickness required for heating water supply lines is 1 1/2 in. • Pulling electrical cable requires 5 ft of access space from end of conduit • Installation of air terminal boxes always precedes air distribution ducts to zone 84 Thus for my review on the constraint based conflict detection of the UBC Chem Bio Project, the total number of constraints I have is 27 and the same is shown in Table 5.2. Sr. No. Constraint Description Source ,;. A] Mechanical Systems Related Constraints 1 The ducts should maintain a minimum clearance from the adjacent walls and slabs. Tabesh and Staub-French (2005) 2 The ducts, needing the largest supports, should be positioned closer to the slab. Tabesh and Staub-French (2005) 3 In case of external insulation of equipment, positioning should account for installation space. Tabesh and Staub-French (2005) 4 The code implies the thickness of the duct's external insulation or internal lining. Tabesh and Staub-French (2005) 5 The minimum standard radius of a round fitting elbow can not be less than its diameter. Tabesh and Staub-French (2005) 6 It is better to install the ducts first, due to their size and inflexibility. Tabesh and Staub-French (2005) 7 Insulation thickness required for heating water supply lines is 1 1/2 in. Tatum and Korman (2001) 8 Installation of air terminal boxes always precedes air distribution ducts to zone Tatum and Korman (2001) B] Plumbing Systems Related Constraints 9 U-shaped over passing creates air traps in pressure pipes; Avoid them. Tabesh and Staub-French (2005) 10 The R W D line can not run bellow the false-ceiling elevation. Tabesh and Staub-French (2005) 11 In assigning space to pipes, should account for installing insulation. Tabesh and Staub-French (2005) 12 Pipes have higher maintenance frequency than ducts; therefore they should not be positioned above the ducts. Tabesh and Staub-French (2005) 13 R W D pipes should maintain a 1% minimum slope. Tabesh and Staub-French (2005) 14 The minimum standard radius of a round fitting elbow can not be less than its diameter. Tabesh and Staub-French (2005) 15 The code implies the thickness of the insulation around the pipe. Tabesh and Staub-French (2005) 16 The placeholder used to hold a 4" vertical stack pipe in a wall, will need at least a 7" wall Tabesh and Staub-French (2005) 17 The R W D routing should connect the vertical stacks of the adjacent floors. Tabesh and Staub-French (2005) 18 A l l Waste/Sanitary Drain stacks have to be connected to the vent stacks going up from that floor. Tabesh and Staub-French (2005) 19 Required Clearance between Heating Water Supply and Heating Water Return Lines is 6 in. Tatum and Korman (2001) 20 Gravity Driven Wastewater drain lines should slope 1/8 in. per foot Tatum and Korman (2001) 21 Access Space required by personnel for valves is typically 12 in., depending on the type of valve Tatum and Korman (2001) C] Electrical Systems Related Constraints 22 The cable tray has to maintain a 60 cm horizontal clearance on one side to provide access to cables. Tabesh and Staub-French (2005) 23 The cable tray has to maintain a 30 cm vertical clearance on top side to provide future accessibility to cables. Tabesh and Staub-French (2005) 24 The cable tray has to maintain a 15 cm vertical clearance zone anywhere on top side. Tabesh and Staub-French (2005) 25 The number of maximum 90 degree elbows from start to finish for a conduit is four. Tabesh and Staub-French (2005) 26 Pulling Electrical Cables requires 5 ft. of access space from the end of the conduit Tatum and Korman (2001) 27 Electrical conduit may rest on pipe racks that contractors attach to walls or hang from trapeze hangers Tatum and Korman (2001) Table 5.2: Final List of Design and Modeling Constraints Governing MEP Systems Unlike in ABS, NavisWorks has the capability for the modeler to do constraint based conflict detection for the 3D Models of the MEP Systems. I have to say that no two projects are the same but in case of MEP, most of the components installed are the same / similar and hence the governing constraints rarely change. Though the documentation on the constraints from the past 85 research efforts was less than what one might actually come across in a project, I found it quite useful in modeling the U B C Chem Bio Project in NavisWorks. Before checking the models for constraint based conflicts, it was necessary to see which are the constraints from Table 5.2 that one can actually model and check for in NavisWorks Clash Detective. Component Property Related Constraints: NavisWorks Clash Detective does not have the function to check for properties of components (e.g.: the insulation thickness of a component, slope of a component, dimensions of a component) and hence I could not model the constraints related to properties of components in NavisWorks. As ABS allows the modeler to predefine the insulation thickness for each component while modeling the same, the modeler should consider these constraints while modeling the components of the building. This incapability of NavisWorks deletes the following constraints from my review: 1. The code implies the thickness of the insulation around the pipe 2. The code implies the thickness of the duct's external or internal lining 3. Insulation thickness for heating water supply lines is 1.5 in. 4. The Rain Water Drainage Line should maintain a minimum 1% slope 5. Gravity-driven wastewater drain lines should slope 1/8 in. per foot 6. The minimum standard radius of a round fitting elbow can not be less than its diameter 7. The maximum number of elbows from start to finish of a conduit shall not exceed 4 8. U-shaped over passing creates air traps in pressure pipes; so it's better to avoid them Component Connections Related Constraints: NavisWorks Clash Detective does not have the function to check for connections of a component with another component in the MEP system, hence I could not model the constraints related to connections of components in NavisWorks. This incapability of NavisWorks deletes the following constraints from my review: 16. The placeholder used to hold a 4" vertical stack pipe in a wall, will need at least a 7" wall 17. The Rain Water Drainage routing should connect the vertical stacks of the adjacent floors 18. All sanitary drain stacks have to be connected to the vent stacks going up from that floor 27. Electrical conduit may rest on pipe racks that contractors attach to walls or hang from trapeze hangers Component Installation Sequence Related Constraints: NavisWorks Clash Detective does not have the function to check for construction sequence of a project, hence I could not model the constraints related to construction sequence of components in NavisWorks. This incapability of NavisWorks deletes the following constraints from my review: 6. Its better to install the ducts first, due to their size and inflexibility 86 8. Installation of air terminal boxes always precedes air distribution ducts to zone Space Related Constraints: NavisWorks Clash Detective does have the function to check for clearance spaces around components and if we use this clearance based clashes on a more liberal level we can check the model for spatial requirements for a component (e.g.: insulation installation space for a pipe). I could not model these spatial constraints in NavisWorks as I had almost no information available with me for the exact value of these spaces required for the components. This lack of information deletes the following constraints from my review: 3. In case of external insulation of equipment, the positioning of the equipment should account for installation space required for the insulation 11. In assigning spaces to the pipes, one should account the space required for installing insulation Position Related Constraints: NavisWorks Clash Detective does not have the function to check for position of a component, hence I could not model the constraints related to position of component in NavisWorks. The modeler should consider these constraints while modeling the components in ABS. This incapability of NavisWorks deletes the following constraints from my review: 2. The ducts, needing the largest supports, should be positioned closer to the slab. Access Related Constraints: The constraints that fall under this category are: 21. Access space required by personnel for valves is typically 12 in. depending on the type of valve; I could not model this constraint in NavisWorks as there was no clear information on what is the access space required for each and every valve in the floor levels. 26. Pulling electrical cable requires 5 ft. of access space from the end of the conduit; NavisWorks Clash Detective does not have the function to check for space from a specific point on a component, hence I could not model the constraints related to codes in NavisWorks. The modeler should consider this constraint while modeling the conduits in ABS by not allowing any component to fall in the 5ft. zone from the end of the conduit. Thus from the 27 constraints I have listed in the Table 5.2,1 cannot model 19 constraints either due to lack of information or lack in capability of the tool I am using for constraint based conflict detection i.e. NavisWorks. To analyze for the conflicts resulting from these constraints, one must use more sophisticated tool or use a more manual (less automated) checking process than NavisWorks. 87 Clearance Related Constraints: The constraints that I have checked for conflicts in NavisWorks on the 5th floor typical lab, 6th floor and main & 2nd floor corridor of the UBC Chem Bio Project are related to the clearances around a component. NavisWorks has the capability to check for clearances by inserting a tolerance limit for the clearance and selecting the component for which one wants to check for clearances. 1. The ducts should maintain a minimum clearance from the adjacent walls and slabs; this constraint is related to the mechanical duct work in the floor area and is important for the understanding the routing of the duct work. The minimum clearance which the code states for this is 25mm-50mm and the same has been used in my analysis of this constraint in NavisWorks. 10. The Rain Water Drainage (RWD) line cannot run below the false ceiling elevation; this constraint is related to the design aesthetics of the false ceiling and is important because if the RWD line is below the false ceiling at any point then the designers will have to either change the elevation of the false ceiling or slope of the RWD Line which has to be a minimum of 1%. 12. Pipes have a higher maintenance frequency than ducts and hence should not be positioned above the ductwork; this constraint is related to plumbing and mechanical pipework in the floor area and is important for future maintenance operations on the pipework which are subject to more wear and tear in the systems. I will be elaborating the results of this constraint under plumbing systems category so that I am at par with the classification done by Tabesh and Staub-French (2005). In NavisWorks, it's not easy to check for the constraint as NavisWorks does not have the ability to check for specific sides for clearances, so one has to model this clearance for the entire zone (in this case assumed as 0.5m) and then manually review the clashes in the zone for just the ones positioned above the duct work. 19. The required clearance between heating water supply and return lines is 6 in.; this constraint is related to the heating water supply and return lines and is important as it relates to the clearance between these two pipes which generally run very closely to each other. So if the required clearance is not maintained, there might be a heat transfer among the pipelines. In NavisWorks, one can check for clearance between these 2 components with a tolerance of 6 in. or 15 cm. 22. The Cable Tray has to maintain a minimum 60cm clearance on any one side horizontally for future access; this constraint is related to the cable tray which is an electrical component in the MEP Systems. This constraint is important as it relates to the clearance required for any future maintenance on them. In NavisWorks, it's not easy to check for the constraint as NavisWorks does not have the ability to check for specific sides for clearances, so one has to model this 88 clearance for the entire zone (in this case 0.6m) and then manually review the clashes in the zone for just the ones positioned horizontally on any one side of the cable tray. 23. The Cable Tray has to maintain a 30cm vertical clearance on the top side for future access; this constraint is related to the cable tray which is an electrical component in the MEP Systems. This constraint is important as it relates to the clearance required for any future maintenance on them. In NavisWorks, it's not easy to check for the constraint as NavisWorks does not have the ability to check for specific sides for clearances, so one has to model this clearance for the entire zone (in this case 0.3m) and then manually review the clashes in the zone for just the ones positioned on the top side of the cable tray. 24. The Cable Tray has to maintain a minimum 15cm vertical clearance on the top side at any point of time; this constraint is related to the cable tray which is an electrical component in the MEP Systems. This constraint is important as it relates to the clearance required for any future maintenance on them. In NavisWorks, it's not easy to check for the constraint as NavisWorks does not have the ability to check for specific sides for clearances, so one has to model this clearance for the entire zone (in this case 0.15m) and then manually review the clashes in the zone for just the ones positioned horizontally on any one side of the cable tray. From the above discussions, it is clear that NavisWorks is more capable to handle clearance related constraints and to check for conflicts generated from the remaining set of constraints i.e. component property related constraints, position related constraints, access related constraints, component installation sequence related constraints, space related constraints, we need a more sophisticated tool than NavisWorks. However, in comparison to ABS, NavisWorks is definitely better as a constraint based conflict detection tool. A detailed report on the results of these constraints that were simulated in NavisWorks to check for conflicts resulting from these constraints is discussed in Section 5.5.3. 5.5. U B C Chem Bio Project Review using NavisWorks 5.5.1. Introduction The study by Tatum and Korman (2001), who were the first to do an extensive study into the MEP coordination process illustrated that the design of MEP systems and the entire coordination process is governed by constraints i.e. MEP coordination process is a type of constraint-based modeling and use of 3D models for this process just make the task a lot simpler as the project 89 participants can see the 3D model of the component in the drawings instead of visualizing the same in their minds as done in the paper based Sequential Comparison Overlay Process (SCOP) or 2D MEP coordination process. These MEP components are tough to visualize as a lot of intrinsic details govern the overall structure and positioning of these components in the desired area. Given the nature of conflicts that one might come across, the visualization of these systems as a whole component using the 2D drawings is cumbersome and often results into a misinterpretation of the exact nature of the conflict that has arose. Also, it is tough for the designers of these MEP systems to model the various constraints right from the preliminary stages of the design as the integration of these systems happens at a stage when all the respective design disciplines have completed the designing and detailing of their respective systems. When I started with my study on this project, the project was almost completed and my only sources of information were the 3D drawings of the UBC Chem Bio Project and the authors, Abdorreza Tabeesh and Dr. Sheryl Staub-French who had undertaken the earlier study of this project (Tabeesh and Staub-French, 2005). Having regular meetings with the authors enhanced my understanding on the work they had done in their study and also helped me formulate my plan of action for my study. Also, not having any access or direct interaction with the project participants limited my knowledge on what actually happened while the project was being modeled. In my meetings with the authors, we discussed what needs to be done further to enhance the knowledge contributed by their work to the industry and the first step we zeroed in on was to do the review of this entire project using a more sophisticated conflict detection tool. Understanding and learning a new tool is always cumbersome for any individual and I too faced the same problem. But the support and guidance of my supervisor, Dr. Sheryl Staub-French helped me to quickly learn the functioning of the tool I was to use for conflict detection i.e. NavisWorks. Before modeling the specific constraints, it was very important to know how many hard conflicts (physical interferences) were overseen in the project and hence the first test that I ran using NavisWorks was an Overall Physical Interferences Test for the various floor areas that were modeled in 3D in the study by Tabeesh and Staub-French (2005) which is discussed in the next section followed by checking for clashes resulting by modeling the various design and modeling related constraints for the project. The results shown in the next sections are only the typical conflicts detected for the constraints modeled, and the detailed results for all the modeled constraints are enclosed in a Compact Diskette (CD) which contains the NavisWorks Drawing File (.nwd) for the 5th floor, 6th floor, Main floor corridor and 2nd floor corridor levels. 90 5.5.2. Results for Physical Interferences (Hard Conflict Test) The first step that I undertook doing a hard conflict analysis of the entire floor level by testing all the components installed in the floor level against itself and also against all the other components installed in the floor level. The Tolerance Limit I inserted for the same was Zero as I wanted to test it for all the possible hard conflicts. 5th Floor Typical Lab: This test resulted in a total of 465 Clashes. On analyzing the conflicts in detail, I found out that most of the conflicts were pertaining to the intersection of the components with the walls of the floor and hence I gave them an approved status as they are components which are passing into the adjacent rooms on the floor levels. Also, some of the conflicts were pertaining to the fittings of the components with each other (for example, a conflict between an electrical conduit and electrical conduit fittings), these also have been given an approved status. The conflicts wherein I saw water pipes going into the kitchen sink and cabinets have also been given an approved status. A total of 417 clashes have been given an approved status by me as I don't think these are clashes which need to be checked for with the consultants or sub trades. A typical approved clash for this floor level is as shown below: 91 • SI L# a: U g a 3SJ5 & ? #| ^ E §8 <>J a < ^  3> & <bj * t ?t o s ? 3: $ |<TQ""g ® r j ® © B a t c h Rules Select R e s e t s Report Name Status Dista Description Found Approved Approved By Clash Point A Display • Exhaust Duct and Wall Approved •0.582B Hard 9:21:45 AM 15/0... 6:39:55 PM.. SSF 21.008m -8.825m 3 282 p Select filter <s » Power Conduit and Wall [Approved v ! -5 57im Hard £21:45 AM 15/0... 6:39:56 PM . SSF 27 808m -1.448m 2.924 IfgAuto Reveal vVall end Power Conduit Approved 0.553m Hard 9:21:45 AM 15/0... 6:39:57 PM. SSF 24.862m 0.488m 2.91V IkJjAiio Zoom L_J| : \'SA\ and Fvhai sst Hi irl Anornven1 -fl Hftn Hard 9 ?1 45 AM 15 0 M M W P M _SSF, ?7 WSm -1 fiR9m 3 1 « Y . ii^jSave Viewpoint •Hahliaht Al v < | j f>| - teml « Name: E-Powr-Cndt Type: ConduS rtem 2 Name:A-Wa« Type-Wall B[s] 5th Floor Final File-June 10th checked on (an 15 20O6.nwd ! * | ~ B j f E-Powr-Cndt • & Conduit v 0 Highlight | Select j B|3| 5th Floor Final Fite l^une 10th checked on Jan 15 2O06.nwd A B l A - W a l l I await v 0 Highlight S e | e c t Figure 5.4: Typical Approved Clash for Fifth Floor Level for Physical Interference Test This leaves us with 48 clashes with active status. These clashes need to be resolved after discussions with the consultants and sub trades. A typical active clash is as shown below: 92 M l 5th Floor Final as on Feb 04 2006 - NavisWorks JetStream (Not for Resale) file Edit View Viewport Review Tools htelp • <Q a G* a a B i ? i « § t v| A E ss «s Q» 1**11 8 o\= Eaten Rules Select Results Report Name Status Data... Descnption Found .Approved Approved By Clash Point A jHsplay • Clash87 Active v -0.115m Hard 9:21:45 AM 15/3... 24 843m 1.288m 33O0T" •Select Hter j*l yjAuto Reveal . • dashSD Active •0.085m Han) 9.21:45 AM 15/0... 24.900m 1 330m 3.30ft • Clash92 • na*ion Active Adive -B.C€5m -MUlm. Had Hsrrt 5:21:45 AM 15/0... ..M-4S..AM.1M!.... 24.826m 1.20Sm 3.30ft,.., 24175m I.TOn 3¥WY VSuto Zoom IB| 3 Save Viewpoint. J <l ii _ _ i > rHiahWTtAil v --Hem 1 1 Name: M-Supp-Duct Tjpe: Duct Name: E-Powr-Cndt Type: Conduit B% 5th Floor Final File June 10th checked on jan 15 2O06.nwd S BiM-Supp-Duct L ODuct v 0 Highlight Select] B § 5th Floor Final File June 10th checked on jan 15 2O06.nwd W B l E-Powr-Cndt L 9 Conduit H 0 Highlight V m i — . . . . . — .. i Ready S—, Q ffi 66 MB Figure 5.5: A Typical Active Clash for Fifth Floor Level for Physical Interference Test In the above clash, we see that a bunch of electrical conduits (4 to be more specific) pass through the supply duct. This clash should have been detected in the modeling stage itself but this clash was overlooked and this clash may have been detected on the site by the on-field personnel after installing the components and would have resulted in a change order thereby affecting the project. Had this clash been detected and brought to the notice of the project participants in the designing stage, then the change order could have been avoided. The active clashes I looked at in this floor level are of the similar nature to the one above i.e. clashes which were overlooked and may have resulted in a change order in the project. 93 6"1 Floor: This test resulted in a total of 185 clashes. On analyzing the conflicts in detail, I found out that most of the conflicts were pertaining to the intersection of the components with the walls of the floor and hence I gave them an approved status as they are components which are passing into the adjacent rooms on the floor levels. Also, some of the conflicts were pertaining to the fittings of the components with each other (for example, a conflict between an electrical conduit and electrical conduit fittings), these also have been given an approved status. A total of 153 clashes have been given an approved status as I don't think these are clashes which need to be checked for with the consultants or sub trades. A typical approved clash for this floor level is as shown below: 6th floor Final as on Feb 05 - NavisWorks JetStream (Not for Resale) file Edit Vjew Viewpoint Review Tools Help Q n £ £ y ^ i n « - a ? ... ^ m go »3 c \ [4 $ ^ $ | Batch Rules Select Results R e p d Name Status ['era Descnption Found Approved Approved By Cash Point * • QashS Old •0415m Hard 2:14:29 AM 05/0... 21910 AM. SSF 24.348m 14.2€Sm 3 55 ClashS Old •0.378m Hard 2:14:29 AM 05/0... 2:19:11AM... SSF 14,365m 12.339m 3.42. • Clash? Old -0.350m Hard 2:14:29 AM 05/0... 2:19:12 AM... SSF 27.670m 17.646m 3.051, • flashS CM / 1 4 / 9 AM 05/11 7-19-11AM SSF 70917m 14?R?m • i ? v < | _ j> Display ;[jSeiect filter [. IglAuto Revea1 f g i Auto Zoom gjSave Viewpoint nwut AI Kern 1 — Name: M-HVAC-Duct Type: Duct Name:A-Wall Type: Wall B@6Bi floor Final as on Feb 05.nwd B l M-rfVAC-Duct 13 Duct 0 Highlight v Bg) 6th floor Final as on Feb OS.nwd BSA-VVall gwaii I Select 1 0 Highlight Select Ready 8 VT> 99 MB Figure 5.6: A Typical Approved Clash For Sixth Floor Level for Physical Interference Test 94 This leaves us with 32 Clashes with Active status. These clashes need to be resolved after discussions with the consultants and sub trades. A Typical Active Clash is as shown below: 'Dl^^filQe § § § n o. § f tfl o = • Batch Rules Select Results Report Name Status (Ma... Descnption Found Approved Approved By dash Point £ feptay # CiashJS oa -0.022m Hard 2:14:29 AM 35/0 14.435m 10.904m 3 .S1:" ' Se-ec: Fier [A # Qash37 Old •0.022m Hard 2:14:29 AM 0 M . . . 21.003m 10.904m 3.81: /%jto Reveal [ j ' • C taMf l OM 4.022m Hard 2:14:29 AM 05/0... 13.477m 13.372m 2.931 ! y_ kin Zoom UB m -flfflftn Hard 214 29 AM M 21185m 12 318m ?<C' V i / Save Viewpoint <| i [>} tanl — Name: HWAC-Hote-Ppe Type: Pipe lem2 Name: P-Watr-Pipe Type: Pipe 6 3 6th floor Final as on Feb OS.rtwd BlM-HVAC-Hotw-Rpe 9 Pipe 0 Highlight a v ¥@6 th floorFinal as on Feb QismT B f P-Watr-Pipe 9 Pipe [Select I 0Highlight Select Ready p ?P , 100 MB Figure 5.7: A Typical Active Clash for Sixth Floor Level for Physical Interference Test In the above clash, we see that the plumbing water pipe is passing through the HVAC hot water pipe. This clash too was overlooked and may have resulted in a change order thereby affecting the project. Had this clash been detected and brought to the notice of the project participants in the designing stage then the change order could have been avoided. 95 The active clashes I looked at in this floor level are of the similar nature to the one above i.e. clashes which were overlooked and may have resulted in a change order in the project. Main Floor Corridor: This test resulted in a total of 207 clashes. On analyzing the conflicts in detail, I found out that most of the conflicts were pertaining to the intersection of the components with the walls of the floor and hence I gave them an approved status as they are components which are passing into the adjacent rooms on the floor levels. Also, some of the conflicts were pertaining to the fittings of the components with each other (for example, a conflict between an electrical conduit and electrical conduit fittings), these also have been given an approved status. A total of 190 clashes have been given an approved status as I don't think these are clashes which need to be checked for with the consultants or sub trades. A typical approved clash for this floor level is as shown below: M Main Floor Final on Feb 0 5 - NavisWorks JetStream (Not for Resale) File Edit View viewpoint Review loots Help • i?) £ & a£ y MI M s Space — • Electrical Lite C e i l i n g -Device / Batch Rules Select Results Report Name Status Dots. . Description Found Approved Approved By Clash Point A : Display s • da*82 [Approved Hard 3:30:24 AM 05/0. 3:34:10AM.. SSF 16.625m 21.002m 3.35I [•Select Fitter • Clash83 Approved •0.025m Hard 3:30:24 AM 05/0.. 3:34:11 AM... SSF 16.625m 1B.702m 3.35f~-' yAuto Reveal • Dash 84 Approved •0.025m Hard 3:30:24 AM 05/0. 3:34:12 AM... SSF 14,225m 23.365m 2JHt_. l*Auto Zoom j • cuss m , AmmyftH -f lWM Hard ,if).:.?4.AM 05/0 3__S AM _SSF 13__.#35" y Save Viewpoirt : < | _ _ _ _ _ _ _ ili:inriiiiin»itiww<«rJ w 1 hrtaNjqht All Hj . - t a i l Item 2 r4ame: Mail floor-Spce Type Space Name: Mam Roor-E-Lfte-Qng Type: Device B_|May2o3oliTi5aiForrn. mainflooraftermath-nointerterence.nwd O S Main floor-Spce 9 Soace 13 Highlight B _ May 20-2005 platform- mainfloor aftermath-no interterence.nwd B S Main Floor-E-Lite-CIng 9 Device I Select I i 0 Highlight Select Ready Pi IB t n « Figure 5.8: A Typical Approved Clash for Main Floor Corridor Area for Physical Interference Test 96 This leaves us with 17 clashes with active status. These clashes need to be resolved after discussions with the consultants and sub trades. A typical active clash is as shown below: |H Main Floor Final on Feb 05 - NavisWorks JetStream (Not for Resale) Rie gdit View Viewpoint Review Toots Help Batch Rules Select Results Repof, j Name • QashSt \ • QashS2 I • ClashS3 I # f l M > i M r Ham 1 ! Name: Main fiorx-Cndw-Pipe : :Type: Pipe Status Dsta Description Found Active ~ T^J -0020m Hard 'ActSre ' -0.020m Hard Active -0.020m Hard Active -ftOISm H«d Approved Approved By 3:30:24 AM 05/0.. 3:30:24 AM 05/0... 3:30:24 AM 05/0... J 3 0 7 4 AM 05/0 - Item 2 Name' Main Roor-Stem-Pipe Type: Pipe O ST CD I • A* X Y Qash Point | 24.132m 31,640m 3.23! 24.040m 31.732m 3.26! 24,230m 31.741m 3 26' 13 [Mm ISIOSm 3 4.1: ' Display j •Select filar [ A <Auto Reveal ViAuto Zoom • Save Viewpoint Highlight All !.r Elg May20 2005platform- mainflooraftermath-nointerference.nwd B3 Main ftoor-Cndw-Pipe 9 Pipe 0 Highlight Select l§laJMa>26-2005 platform- mainfloor aftermath-no interference.nwd A B9 Main Floor-Stem-Pipe L-13 Pipe v 0 Highlight r i ^ T l Ready , . 6o M B Figure 5.9: A Typical Active Clash for Main Floor Corridor Area for Physical Interference Test In the above clash, we see that the cndw pipe is touching the stem pipe. This clash should have been detected by Tabesh and Staub-French (2005), but this clash went unnoticed and I believe this clash may have been detected on the site by the on-field personnel after installing the components and may have resulted in a change order thereby affecting the project. Had this clash been detected and brought to the notice of the project participants in the designing stage then the change order could have been avoided. The active clashes I looked at in this floor level are of the similar nature to the one above i.e. clashes which were overlooked and may have resulted in a change order in the project. 97 Second Floor Corridor: The test on this floor level resulted in a total of 36 clashes. Out of these 36, 27 have been status of approved as they pertain to components going through walls and slabs. A approved clash is as below: given a typical ffi Second Floor Final as on Feb 05 - NavisWorks JetStream (Not for Resale) 1- 1  a1 IS Fte Edit Vjew vTewgoint g e v i e w l o o t s He lp ; D © fi*a* a * O a « # # n r > § t iff ] l _ J ! «5[Ajia. <S> < a © © ® Batch • Ruies j; Select Results | Report Status Description Found Approved Approved By Gash Point Display Name • Oash34 Approved •0000.. Hard 4 27:07 AM 05/0... 4 28 51 AM... SSF 15.039m 32.604m 8 351 [7 Select F*er • Clasfi35 Approved •0000... Hani 4 27:07 AM 05/0... 4 28 53 AM... SSF 15.750m 32 604m 7.851 lylAuto Reveal | Approved JJ -0.000.. Hard 4:27:07 AM 05/0... 4:28:54 AM SSF 9.434m 32.834m U2SCS [•lAjto Zoom V Save Viewpoint . 1 < | _ _ I Hrahtqht. A l - Ham 1 Name: 2nd Row-Other Walls 'roe Wal Rem 2 :Name: 2nd Roor Spaces type Space B _ Second FlooFFinal a"s~on Feb 05.nwd BM 2nd Floor-Other Walls 9 Wall [_ Highlight ~i§[_ Second Floor Final as oo Feb 05.nwd B _ 2nd Floor Spaces S3 Space | Select | 0 Highlight Figure 5.10: A Typical Approved Clash for Second Floor Corridor Area for Physical Interference Test The remaining 9 clashes need to be resolved after due consultation with the project participants. A typical active clash is as shown below: 98 M Second Floor Final as on Feb 05 - NavisWorks JetStream (Not for Resale) • • • • H H H I File g E d i t ^jew Viewpoint Review loots Hetp j • < & G » G * c# Q & * e m T, 6S t Hf? [| ^ w 8g «J Q. :<i ^7 *» *b! * * s * <te 0 g (."*) 1 a © © © Batch : Rules : Select Results : Report Name Status • Qash26 Active • CJasri27 Active • C « * 2 8 .Act,ve # CU«h:>1 Art,v« Name ES Pipe same as Cold ware* Type Dipe Oista.. : Description : Found •0.016m Hard 4:27:07 AM 06/0... -0.015m Hard 4 27:07 AM 05/0... • -0013m Hani 127 07AM 05/0 n nir>n H»rt 1 7 i m A M ns/n Approved Approved By Oash Point * 10 344m 34.123m 7.55'' 10.944m 33 923m 7.55! 1 7 592m 34 263m 7 550. , Name 2nd Floor HVAC -HotWtf piping Type Pipe B J ^ Second Floor Final as on Feb 05.nwd B * 2nd floor Plumbinc < J HHighSgH Second Floor Final as on Feb 05.nwd B S 2nd Floor HVAC -HotWtr piping Q Pipe 0 Highlght Display .Select F*e, * SBAuto Reveal [•T.Auto Zoom y Save Viewport : HrahtoN All M Ready S ^ L , i L , H « Figure 5.11: A Typical Active Clash for Second Floor Area Corridor for Physical Interference Test A Total of 893 hard clashes/physical interferences were detected by me in my review of the UBC Chem Bio Project using NavisWorks. Of these 893 clashes, 106 are of the status active which implies that Tabesh and Staub-French (2005) in their missed 106 interferences, (as they have mentioned in their study that the conflicts they identified were addressed by the project participants). All these 106 clashes should have been identified using ABS but then as mentioned in my discussion on the limitations of ABS; the rendering ABS gives when the modeler runs the collision detection tool is so minute that it becomes tough for the modeler to review the entire drawing for the clashes. In addition to the number found above, I am still to analyze the floor level for the constraints (See Table 5.1) that govern the MEP Systems which is the next step of my review and document the results of the same. This is discussed in the next section. 99 5.5.3. Results for Constraint Based Conflict Detection 5.5.3.1. The ducts should maintain a minimum clearance from the adjacent walls and slabs Test Name: All mechanical ductwork should maintain a minimum clearance of 25mm-50mm from all the adjacent walls and slabs. Test Description: This constraint governs the positioning of the ductwork of the mechanical systems against the walls and slabs of the floor level. The code for mechanical ductwork states that the ducts should maintain and minimum clearance of 25mm-50mm from the adjacent walls and slabs and hence I have considered the same in my analysis. In analyzing this constraint, NavisWorks, creates a zone of the desired tolerance (in this case 50cm) around the ductwork and checks for the walls and slabs that intrude into this zone of clearance desired by the constraint. The Ductwork generally passes through the walls and slabs into the next room or floor level and hence any clash of this type is not a violation and hence needs to be given an approved status; all other types of resulting clashes may be given an active status depending upon the result. Rules: We are ignoring clashes between the following for this test-• Items in the same layer • Items in the same group/block/cell • Items in the same composite object • Items in previously found pair of composite objects • Items with coincident snap points Selecting Items for clash testing: For this test, I have tested all the mechanical duct work in the floor level against all the slabs and walls in the floor level i.e. the objects M-Exhs-Duct, M-Exhs-Duct-Fitt, M-Supp-Duct, M-Supp-Duct-Fitt against all the wall and slab objects in the floor level. I have not checked the tab "self intersect" for this test as this does not require an internal testing among itself. Clash Results: • 5th Floor Level: On running the clash test, I detected 12 clashes in the floor level among the selected objects. On checking the results of the tests, I found out that all of these clashes are representing the duct work passing through the walls or slabs into the next lab or floor level. These clashes are therefore given an approved status. A typical approved clash result is shown below: 100 Rules Select Htanl Name: H-Supp-Duct Type: Doct Repot B@ 5th floor Final as on Feb 04 2006.rtvvd Si M-Supp-Duct 9 Duct _ Highlight •lem2 Name A-Wal Type: Wal Name Status E t e . , DesatSion Found Approved .Approved fly Gash Port * • D a r t Approved v | -O.500m Qearance 11221 AN I M L U I S P M . . . SSF 23.153m 1.155m 3A35r • Qashl "ApproveT -0.625m Clearance 3:12:28 AM 15/Q... 5:12:46 AM... SSF 22.155m 4312m 3.134 • #Clash2 Approved -0.532m Qearance 9:12:28 AM 15/0... 5:12:52 AM... SSF 2 1 . & -S.S25m 3.283, , • OwhS Annmyeri -f: c , » i QftnTanre... »1>MAM15n1 _Jt1>5?AM SSF 2794am 1 W i n 311? v <| r > l | . a 1 „ i '_>] Display "Select Rler _Auto Reveal 0 Auto Zoom SSave Viewport nrtahWitAII 8 _ 5th Floor Final as on Feb 04 20O6.nwd~ i f M M • 9 Wal Select] Height Figure 5.12: A Typical Approved Clash for Fifth Floor Area for 5.5.3.1 • 6 Floor Level: This test resulted in 0 Clashes. • Main Floor Corridor: This test resulted in 19 Clashes and 6 have been given a status approved as they pertain to the duct work passing through the walls and thus do not violate the constraint. A typical approved clash is shown as below: 101 S Main Floor Final on Feb 05 - NavisWorks JetStream (Not for Resale) Fie Edit View Viewpoint Review Tools Help itch ii Rules ;eled Resuis Report Name Status Data... Description Found Append Approved By dash Point * & s o l a V lasrl .Approved •0572m Clearance 225 55 AM 30/1... 4 08 38AM . SSF 9 440m 33 032m 3 781s -jSetect Fier » • Oash2 Approved -0.529m Ctearance 2:25 55 AM 30/1.. 4:08:40 AM... SSF 17580i> 26 128m 3601 JriAutoRewal 17 092m 17 843m 3 75T "*>*lZxm I5 4«m l-t-vTft, ,47!.v 'Save viewport • 05*3 Approved j v] -0.325m Clearance 225 55 AM 30/1.. 4:08:31 AM.. SSF Srwnvftl •0 305m Qearance ...?..?555.AM»/1 .4:08:43AM SSF < _ iiilliiliiii iilJJiiil^BJijII > 'FiarkjN Al w Hern 1 Hem 2 Name: Main Roor-M-HVAC-Ductwork Type: Duct Name Main floor-A-Wall ;Type:Wa1 I^^ MaitinooirFTrtal onTeb 05.nwd B f Main Floor-M-HVAC-Ductwork a Dud 0High!ght | Select] B@ Main Floor final on Feb 05 nwd a f Main Floor -A-Watl 9 Wall 0Hohlght | Select | Ready p P) IB Bit. Figure 5.13: A Typical Approved Clash for Main Floor Corridor Area for 5.5.3.1 The remaining 13 which violate the constraint have been given an active status and need to be resolved after discussion with the project participants. A typical active clash is as shown below: 102 H Mam Floor Final on Feb 05 NavisWorks JetStream (Not for Resale) iiiiiiiiiiiiiiiiiiwii uye File gdrt $ew Viewgoint Review Took Help • "a a ; a* B# y a B a - >o • S f Iff I'MH 88 «3 'A 0 «*• & f ft Bach Rules Select R«u«= Report Name Status Drta Description Found App^.ec Approved By I dash Point MM PMWV '"'') I Dash 2! Actve v j 0.025m Clearance 2:25:55 AM 30,1 17.050m 26»22m 4.23" 1 Select F*er A : • Clash27 Active""' 0.025m Clearance 2.25.55 AM 30/1.. 15.775m 26.647m 4 23' ViAuto Reveal * Oash2S Active C :25m Clearance 2:25 55 AM 30/1.. 16.825m 27047m 423", I j |SSrWe&ee. 1 <j Active 0075m Clearance 7 75-55 AM 30/1 ^ . . . v . / /Save Viewpoint ,mm> >: il IHohlioht Ail |vf tarn 1 - — 1 r tern 2 - - ~ Name: Main Roor-M-HVAC-[>jctwork Type: Duct Name Main Floor A-Slab Type: Slab Main Floor Final on Feb 05.nwd BM Main Floor-M-HVAC-Ductwork 1 —QDud A • Hj B^] Main Floor Final on Feb 05.nwd eg Main Floor-A-Slab 9 Slab I yHghlght 1 Select 1 ! HHghlght Ready " " *=» B *K ' AIMB Figure 5.14: A Typical Active Clash for Main Floor Corridor Area 5.5.3.1 • 2" Floor Corridor: This test resulted in 0 Clashes. 5.5.3.2. Pipes have higher maintenance frequency than ducts; therefore they should not be positioned above the ducts Test Name: All Pipe work (Mechanical, Electrical and Plumbing) should be located below the Ductwork in the floor level. Test Description: This constraint is important as it governs the routing of the pipes and also the future access to the same for maintenance. I did not have a clear idea of what zone of clearance I could use for this test. On discussion with my supervisor, we decided on a limit of 0.5m zone i.e. any pipework above the ductwork within this zone of 0.5m will be reported as an active clash (See figure below). In NavisWorks, there is no in-built functionality that enables the user to just check for the clashes in a particular side (in this case top side of ducts), so I had to manually review all the resulting clashes and check for those positioned above in the zone of clearance which was therefore reported as active clashes. 103 Zone of Clearance Modeled by NavisWorks Duct Work Rules: We are ignoring clashes between the following for this test-• Items in the same layer • Items in the same group/block/cell • Items in the same composite object • Items in previously found pair of composite objects • Items with coincident snap points Selecting Items for clash testing: For this test, we are going to test all the mechanical duct work in the floor level against all the pipe work in the floor level i.e. the objects M-P-Cold Water, M-P-Fumehood, M-P-Gas, M-P-HTM, M-Stem Pipe, M-Stem Pipe Fitt, M-Watr Pipe, M-Watr Pipe Fitt against M-Supp Duct and M-Exhs Duct in the floor Level. We are not going to select the tab self intersect for this test as this does not require an internal testing amongst itself. This test will be a run as a clearance test with a 0.5m tolerance limit. Clash Results: • 5th Floor Level: On running the clash test, I detected 206 Clashes for this constraint. Although this constraint had to be verified by visual survey of the floor, I have tried here to model the same in NavisWorks and get quicker review of the results. 198 of these clashes did not violate the constraint and were given an approved status. A typical approved clash is as shown below: 104 ;H 5th Floor Final File-June 10th checked on jan 15 2006 - NavisWorks JetStream (Not for Resale) £fc E « View Wewoolnt Review Took Help ]Q«*P3A a sis T T C B" ^ * th •>3 * - \ o ,• g jo]-) -• !•] 9 , 3 ' $ © Name Status Dista.. Description Found Approved Approved By Qash Point * • Oashl39 Approved | v| 0 395m Clearance 9 16:43 AM 15/0.. 5 47:09 PM. . SSF 26.380m -5489m 3.167 • QashHD .Appmvec! 0 397m Ctearance 9 16:43 AM 15/0... 5 47:11 PM SSF 28.427m -5 865m 3.143 J - / :L Approved 0.397m Ctearance 9:20 26 AM 1570.. 5:4713 PM SSF 28 434m -5.759m 3 128' ' * (W t j f i l ArmmveW 0401m 9 70?fiAM 15/0 5 4714PM .....SSF. ?m79m -5637m 3 I 1 4 v < I > Display Select Fto MAuto Reveal y,Auto Zoom './.Save Me»pomt : HnhlrahtAI i Ten 1 Name MP-Gas Type: Pipe te/n i Name: MExhs-Duct Type: Duct * I B[s) 5th Floor final File-June 10th checked on jan 15 2O06.nwd EM i flhgSth Floor Final File-June 10th checked on jan 15 2006.nwd [ A ] 0gM-P-Gas BM M-Exhs-Ducl 0 Pioe V 0Duct v [Seiea I • i tllHghhght [ Select j TP ,.61MB Figure 5.15: A Typical Approved Clash for Fifth Floor Level for 5.5.3.2 The remaining 8 clashes violate this constraint and should be addressed by the project participants; a typical active clash is as shown below: 105 y 5th Floor Final File-June 10th checked on jan 15 2006 - NavisWorks JetStream (Not for Resale) • • H i B o n fte Edit Vjew VewDotrst Review lools Help D © oS & e* y i4 * % # o S t * ? ; < l R ! « 8 « J ^ I 2 i ? > ^ * » & < b l r | o |_ ' |" <s> ( »|cf|l$l (J) Batch Rules Select Results Repp, *Jame Status Data. Description Found Approved Appmved By ' umru Clash Point A : W a y # Ctash44 € Clash?* # O n * IN Active 0146m Clearance .Active fl 14Gm Clearance Active jvj 0 238m Clearance V*.w 0 ?fi1m O I J V W W 9 1643 AM 15/0 9 1543 AM 15/0.. 9 16:43 AM 15/0... 9?n?fiAM 1R/f) 29 303m -5473m 3 521 Select Fier A 28 499m -5173m 3 521 < " u , ° 27 284m 2201m 3 514 vAutoZoom 74HU* OlUtta, 1S?f,r ' S ^ e Newport < j f>] HohMnt Al " Sen 1 em 2 Name M-Watr-Ppe Type. Pipe Name M-E*s Duct Type Duct B|fiS| 5th Floor Final File-June 10th checked on jan 15 2006.nwd e g M-Watr-Pipe L~ 0Pipe iv Sth Floor Final File June 10th checked on Jan 15 2006.nwd A ; BSfM-Exhs-Ouct a Duct it (3 HtgMkjM jjjjjjjj ElHrghtghl [ Select | Ready Figure 5.16: A Typical Active Clash for Fifth Floor Level for 5.5.3.2 6th Floor Level: This test resulted in a total of 135 clashes. Out of these, only 6 clashes violate this constraint and they have been already identified in the hard conflict test wherein we had pipe work intersecting the duct work. A typical approved clash is as shown below: 106 6th floor Final as on Feb 05 - NavisWorks JetStream {Not for Resale) i-JtsL'S £Se £dit View Viewpoint Review Tools Help ovi&aaaha • • - « - «s ? *? |; H n «5 «> o o> *» c? <i» i <* * ft «tt 9i «' S •c |— <•>! ® !® !® c5 C; «* pa A JH <sj) I T I: B- j . -MQt e : • .... ' ' I Batch ; Rules i Select Results Report • Clash 1C' • OMhll • Clash 12 \ Dtsta.. Deacnptlon ! Found 0.013m ' ' 'OMranc 'e3:09:33 AM 05/D.'. i Approved v] D.G13m Clearance 3:09:33 AM 05/0.. 'Approved' : 0 016m Clearance 3:09:33AM 06/0.. . 'Annt nv*v< C C l fim O^Jiwirf" . W r - T - . l AM (Vi T . .Approved 3.13:30 AM 3:13:31 AM... 3-13:32 AM. \ AM Approved By SSF SSF SSF ...SSF. daoh Point * 18 W7m 13 947m 2 9€* 15 609m 15 925m 2 96' IE&45m 13947tn 2%. Dwplay Se*e«Ffter ^ V.Auto Reveal "Auto Zoom ySave Vle-wport 'Hahhoft Al V Name: M HVAC-Duct Type: Subentity Name M-HVAC-Hotiw Pipe Type: Pipe S[ej6tr. floor final as on fet> 05 nwd I B]3] 601 floor Final as on Feb 05.nwd e i M HVAC Duct e S M-HVAC-Hotw Pipe IDS'Dud v r3 Pioe B 5] H-gnl-g-rt | Select ] HigNtght |~S«iect ] Ready Figure 5.17: A Typical Approved Clash for Sixth Floor Level for 5.5.3.2 • Main Floor Corridor: This test resulted in a total of 169 clashes. Out of these, only 2 clashes have to be resolved as the pipe work is above the duct work. A typical approved clash on this floor level is as shown below: 107 file gdtt View Viewpoint Review Tods Help • © »• as a* g a f s § f a •« «3 < i J 4 f 7 ^ «$ts-«b <fc o 5, fg S © © © Batm Rules Select Results Report Name Status Dtsta Description Found Apptwed Approved By Oash Point Dnphy . • CJa*22 Approved 1 rj 0.107m Clearance 3:4313 AM 05,0. 351:39 AM.. SSF 13.061m 31485m 3.511 C 'Select Fitter A • CJash23 .Approved 0110m Clearance 3:49 13 AM 05/0 . 351:41 AM... SSf 17.224m 19.175m 3.451 gJAute Reveal VM • Clash24 .Approved ** 0.110m Clearance 3:49:13 AM 05/0.. 3:51:42 AM.. SSf 17224m 19175m 3451, V^ Auto Zoom l # r w i?6 AnnmveH Clearance 349 P AMIS'- f! 3:5143 AM 15 17*n 19 371m VjSave Viewpoint < 1 > HHaWghl. All | B Name Man FJoor-Horw-Pipe Type Pipe fB^K^pK^OOSQianorm - matnRoor aftermath-no interference, nwd | BM Main Floor-Hotw-Pipe I fifPipe B Highlight Name Main Floor-M-HV.AC-Ductwork Type Duct B^May 20-2005 platform- mainflooi aftermath-no interterence.nwd BM MainFloor-M-HVAC-Ductwork StDuct [Select ] 3Highlight Figure 5.18: A Typical Approved Clash for Main Floor Corridor for 5.5.3.2 A typical active clash on this floor level that needs to be resolved with discussion with the project participants is as shown below: 108 Floor Final on Feb 05 - NavisWorks JetStream (Not for Resale) wwgpint Review Toots Help • • a ? V? | m , m 88 «5 d . cA < • « » I Fie Edit J0a D 0 t i a : » ' H A * Q « t ! P A JJ ^ r r C & <ta <? » • » o | - <s> ® rj ® o B a c h Rules Select Results [ R e p o l i ; Name | • Casl-S : • OashlO I • Clash 11 Status Dista. : Description -Approved 0 042m Clearance Active 0 044m Clearance Active " 0044m Clearance Found 3:49 13 AM 05/0 3:49 13 AM 05/0. 34913 AM 05/0.. 3 4913 AM M fl Approved Approved By 3 50 35 AM SSF Clash Point ' 16 792m 19 318m 345 15.649m 19 623m 3 64 15 549m 19423m 364. Wl35fim 1fi?24m 371** Display • S s M f f t v I (yijAoto Reveal I BAuto Zoom V Save viewpoint Hohklhl Al Hem 1 Name' Main Roor-Hotw-Ppe Type: Prpe Bjr^ May 20-2005 platform- mainfluui attermath-no Interlerence.nwd 1 C i Main floor Hotw Pipe 0 Pipe (3"ghl,ght Name Mam Roor M-Supo-BranchDuct Type Duct Elf? May 20-2005 platform maintloor aftetmath-no intettei eiroe nwd O H Main Floor-M-Supp-BrancrtDuct a Dud PlHghfcght (Select I S — . i i = ^ = 59 MB ' Figure 5.19: A Typical Active Clash for Main Floor Corridor Area for 5.5.3.2 2nd Floor Corridor: This test resulted in 0 clashes. 5.5.3.3. The Rain Water Drainage (RWD) Line cannot run below the false ceiling elevation Test Name: The RWD Line cannot be below the false ceiling elevation Test Description: This constraint governs the routing of the RWD Line. If the RWD Line runs below the false ceiling, then not only does it violate the constraint but it also looks aesthetically unpleasant when the project is complete. To check for this constraint, I have made the assumption that any hard clash between the RWD Line and the False Ceiling will be considered as an active clash as it implies that either the RWD Line is going up through the false ceiling from below or vice versa and needs to be addressed. Rules: We are ignoring clashes between the following for this test-• Items in the same layer • Items in the same group/block/cell • Items in the same composite object • Items in previously found pair of composite objects • hems with coincident snap points 109 Selecting Items for clash testing: For this test, we are going to test the RWD Pipe in the floor level against the ceiling in the floor level for a hard clash. The tolerance limit we are keeping for this clash test is 0 as any intersection between these 2 objects becomes critical with respect to the appearance of the ceiling. We are not going to select the tab self intersect for this test as this does not require an internal testing amongst itself. Clash Results: • 5th Floor Level: No RWD Line present to check for this constraint • 6th Floor Level: No RWD Line present to check for this constraint • Main and 2nd Floor Corridor: On running the clash test, I detected 0 clashes in the floor level among the selected objects. This result was obtained as the redundant RWD Line in the floor level was detected during the modeling stage and the same was resolved then. 5.5.3.4. The Cable tray has to maintain a 60cm horizontal clearance on one side to provide access to cables Test Name: Cable Tray should maintain a 60cm horizontal clearance on any one side. Test Description: This constraint governs the horizontal clearance for a cable tray system for future access to the cables in the same. In NavisWorks, there is no in-built functionality that enables the user to just check for the clashes in a particular side (in this case any one horizontal side of the cable tray), so I had to manually review all the resulting clashes and check for those positioned on any one horizontal side in the zone of clearance which has to be reported as an active clash. Rules: We are ignoring clashes between the following for this test-• Items in the same layer • Items in the same group/block/cell • Items in the same composite object • Items in previously found pair of composite objects • Items with coincident snap points Selecting Items for clash testing: For this test, we are going to test all the Cable Trays in the floor level against all the components in the floor level for a clearance clash and we are not including any self intersection among the components. The tolerance limit we are keeping for this clash test is 0.6m. 110 Clash Results: 5th Floor: There are no cable trays in the Fifth Floor Level so this test is redundant for this area Ah 6 Floor: This test resulted in a total of 77 clashes. All of these are given approved status as they all tend to give the cable trays the necessary clearance on one side horizontally. A typical approved clash for this constraint on this floor level is shown as below: jiftl 6th floor Final as on Feb 05 - NavisWorks JetStream (Not for Resale) £te Edit Yje*ft VewQOint Revew Tods Help i • & i ? G * G f a H m m m « c # t »t?[ jQass(53 A j e rr i : * <.-*<*m °5 .^ i<i 4> f°i s - <b *i> ft* 93 to j—I <3>: ® ! i 3 j© S) 3.esulls R e p o ;t Name • Cwe-1? • Clash13 CM>M Status Approved ; Apptcved Approved inn '^.vri Owta . 0 001m 1 0 001m 0 025m Description Found Clearance Qearance Clearance 2 43 13 AM 05/0 2:4313 AM 05/0. 2:43:13AM 05/0. i*J3 tlAMfft/O Approved 2:45:25 AM . 2:45:2? AM .. 2:45:29 AM .. ?45 11 AM Approved By SSF SSF SSF SSF Clash Point g 13.914m 1233Sm 2 701 13.914m 13025m 2.T0H| 27.2S5m 14.963m 2.85:" 7? 410m 14 9K3m ?f t« | inSeled Filler » ii/Auto Reveal >r.Auto Zoom Save Viewport ([ Hghloht Ail " Name: E-Powr-Cabi Type: Cabie Tray 8[a| 6th floor Ftnai as on Feb 05.nwd BW E-Powr-Catt 0 Cable Tray 3 Highlight [ Select | *«rfi2 Name: A-'Wall Type: Wall B[s] 6th Boor Final as on Feb 05jwd S S A-Wall QJ Wall S yV..-.., 93 M6 Figure 5.20: A Typical Approved Clash for Sixth Floor Level for 5.5.3.4 • 2 nd Floor Corridor: This is test resulted in a total of 54 clashes out of which 50 clashes are being given approved status as they interfere in the vertical clearance and not in the horizontal clearance as defined by the constraint. A typical approved clash for this constraint on this floor level is as shown below: 111 x f,j.,.J!....... Batch Rules Sdect Jesuits Report Name Status Diss Descnpticn Found Approved Approved By Clash Port A Display # OashS Approved 0026m Qearance 11 53 59 AM 11/ 11 54 11 A SSF 10 944m 33727m 753' HSeleetfihr 1^ .... i Approved _ Approved J 0.026m Qearance 11 53:59 AM 11/... 11:54:13A... SSF 10.944m 34.47tm 753' yAuio Reveal ™ • Qnf-i: ~~ C.023m Qearance 11:53:55 AM 11/... 1" 54 ISA SSF 10.944m 33.527m 753! : VjAjtO Zoom _ Arwmyed JSMSB Opnrannp 11 5.159 AM 11/ r-54 21 4 _SSF 15471m .T3fi35m 7 * 7 i v Save Viewpoint > InHoMohiAn m r lm 1 -\ Name: 2nd floor - Cable and Cond Type: Cable Tray - ran 2 Name: Sid floor Plumbing Type:Ppe B @ May 19-2005 platform- 2nd after math nov 27.nwd Ej e f 2nd Floor - Cable and Cond ~S Cable Trav v [3 Highlight | Select | 8 § May 19-2005 platform-2nd after math nov 27.nwd Q B S 2nd floor Plumbing L-gPioe v Figure 5.21: A Typical Approved Clash for Second Floor Corridor Area for 5.5.3.4 Of the 4 clashes which have been given an active status, 3 clashes are of the pipes going through the cable tray which I believe is a design error and needs to be rectified as seen below: 112 Batch Rules Select Results Report i Name * Clasr,2 : * ClasM 1 • Clash4 '• * Oa*S f< | *em 1 Active Active Dista Descnption Found •0 104m Qearance 1 2614 PM 28. Apprpved .Approved By v -0.016m Clearance 12614 PM 28/1 •0.015m Clearance 12614 PM 28/1.. -nmjm Hearanne 1JSJ4. PM 28/1 Qash Port i 11.144m 32.844m 75®W 10 944m 34123m 7.55! 10 344m 33.923m 7.551. Display Select filter vlhxo Fleveal ViAuto Zoom W W . Mm* 7551v ylSa*= Viewport >: > -mm* v ; Name: 2nd Rocr - Cable and Cond iType: CaNe Tray Item 2 —ZZZZ Name HTM pipe same ss DHotW *1/4" for H-Cable .1 5"hsul Type Pipe l i @ May 19-2005 platform- 2nd after math rvov 27jtwd 8 S 2nd Floor • Cable and Cond S Cable Tray 0 Highlight B\3J Hay 19-2005 platform- 2nd after math nov 27.nwd B i t 2nd floor Plumbing 9 HTM pipe same as DHotW -1'4" for H-Cable «l.5"msul 0 Hghlight Figure 5.22: A Typical Active Clash for Second Floor Corridor Area for 5.5.3.4 The remaining active clash has the cable tray passing through a device which is a component of Electrical Lite Ceiling on the same level and this clash needs to be resolved with due consultation with the respective consultant and the sub trade, the same is shown in the figure below. 113 Batch Rules Select Resub Report Name ! Status Dista. Description Found : Approved Approved By Dash Poinl § : Qailhi * Cash3 • dasr.4 Active Active Active Active v C 104m •0.016m •0.015m -nnnjm Clearance Clearance Clearance nearanne 126 14 PM28/1... 1:26:14 PM 28/1... 1:26:14 PM 28/1... J7fi;1.4JM 78/1 11.144m 32 844m 7 551 10 944m 34.123m 7.551 10 344m 33 923m 7.561 115144™ 34 275m 7 55I V : < | > •• Display > U Select Pier A . S?Auto Reveal I g Auto Zoom j«/jSave Viewpoint • HipMghtAJI v • Hem I - > Name: 2nd Roor • Cabte and Cond Name: 2nd Floor E-lite-Ong Type: Cable Tray Type: Device 1 e|3| May 19-2005 platform- 2nd after math nov 27.nwd A : | B@May 19-2005 platform- 2nd after math nov 27.nwd A I BM 2nd Floor -Cable and Cond ] BM 2nd Floor E-Ute-CIng I '• 0 Cable Tray |v I Qi Device -0 highlight | Select ] 0 Highlight | Select | Figure 5.23: Active Physical Clash between Electrical Ceiling Device and Cable Tray in Second Floor Corridor Area Main Floor Corridor: This test resulted in a total of 46 clashes of which 45 have been given approved status. A typical approved clash for this floor level and this constraint is as shown below: 114 I on Feb 05 - NavisWorks JetStream (Not for Resale) Fte grit View ViewQOinl geview Tools Help • <a i * u & a >s * • " • i i •V?j ?! 8g «3 Q> :4 O O " r * f » i c - «> © ® ® ca arch Rutes Setect Results Repot Name i Status : Dista... Description Found Approved Approved By i Qash Point Dts&'av • Oashl .Approved -0224m Qearance 12 56:02 AM 30/.. 4:3511 AM .. SSF 15.7€4m 30.%4m 3150m jnSdoct Rler [<y • Cash 3 Active -0 041m Qearance 12 56:02 AM 30/.. 14 9S?m 24.415m 3215m V.Auto Revea> i ^proved f v] 0.050m Qearance 12:56:02 AM 30/.. 4:35 14 AM .. SSF 15403m 24.865m 3275m yAuto Zoom *> Save Viewport <] . _ .-., -::,-,^ g;,,:.x:/ > Name E-Powr-Cabl Type Cable Tray -•«w 2 Name: Main floor-Spce Type - Space ^^l^nfioQtf\na\ on Feb 05.rwd QgE-Powr-Cabt 9 Cable Tray BM Main floor-Spce 1 13 Space | Select | 0 HigNigh Figure 5.24: A Typical Approved Clash for Main Floor Corridor Area for 5.5.3.4 The active clash in this floor level for this constraint is as shown below: 115 Mi Main Floor Final on Feb 05 - NavisWorks JetStream (Not for Resale) Be Edit View Vrewpfflnt Review Tools Help D <Q £ * c* g * * = ? * « * t r ^ B 88 o5A ^. f>'<• *» I : 0 « ® p a A J) «s n r: 5" % -M -« w s ! 9 0|.» jo] —1 -> l+ l i ^ O © © Batch Rules Select R«u«s R e p 0 « Name Status M a . Descriptktfi Found Approved Approved By •ash Port DUplay - - — - | • dashl .Approved •0224m Clearance 12 56:02 AM 30/.. 4:3511 AM.. SSF 15.764m 30 964m 3150m i _! Select Filer " S * Qash3 [Active H -0.041m Clearance 12:56:02 AM 30/... 14.967m 24.415m 3215m | iVlAuto Reveal 9j • J ds> : Approved 0050m Clearance 125602 AM 30/. 4 3514 AM SSF 15 400m 24.665m 3 275m B Auto Zoom • Save viewpoint < > HontahtAI v Name E-PowrCaW Type Cable Tray-s ' Main Floor final on Feb 05.nwd A BSE-PowT-Cabl O Cable Tray V 0 Hghkjnt [Select] Name Main floor-M-Sanr-Pipe-Vent Type Pipe B]3 Main floor Final on feb 05.nwd B% Mam floor-M-Sanr-Pipe-Vent SPioe 0 F*ghtgnt i v Ready S _ 2 _ = ^ = 5 9 M B Figure 5.25: A Typical Active Clash for Main Floor Corridor Area for 5.5.3.4 5.5.3.5. The Cable tray has to maintain a 30cm vertical clearance on the top side to provide future accessibility to the cables Test Name: Cable Tray should maintain a 30cm vertical clearance on the top side. Test Description: This constraint governs the vertical clearance for the cable trays for future access. In NavisWorks, there is no in-built functionality that enables the user to just check for the clashes in a particular side (in this case top side of the cable tray), so I had to manually review all the resulting clashes and check for those positioned above in the zone of clearance which has to be reported as an active clash. Rules: We are ignoring clashes between the following for this test-• Items in the same layer • Items in the same group/block/cell • Items in the same composite object • Items in previously found pair of composite objects • Items with coincident snap points 116 Selecting Items for clash testing: For this test, we are going to test all the Cable Trays in the floor level against all the components in the floor level for a clearance clash and we are not including any self intersection among the components. The tolerance limit we are keeping for this clash test is 0.3m. Clash Results: th • 5 Floor: There are no cable trays in the Fifth Floor Level so this test is redundant for this area. • 6th Floor: This test resulted in a total of 36 clashes and 26 of these were pertaining to the horizontal clearance between the cable tray and the components in the floor level, so they have been given a status of approved. A typical approved clash for this constraint on this floor level is as shown below: S 6th floor Final as on Feb 05 - NavisWorks JetStream (Not for Resale) Ne Edit Vew viewpoint Review loots Help [ D © li* ti ti a ^ «"> a f t f ^ e V J O . ^ ^ * ^ ' Q « P k JB$nr;e-<&i.*ini «S 5 •': & i o R <e> $ of® eji Batch Rukss Setect! Results j Report Name Status Dista... Desciption Found Approved Approved By Oash Point ; A • Clash 12 Approved 0.001m Oearance 2:43:13 AM DM... 245.25 A.M... SSF 13S14m 12.339m 2.701 • Oa*13 • dash 14 * Clash 15 Approved Approved ... r AnnmveH j | 0.001m "' 0.025m Oearance Oearance fjearanre 2:43:13AM 05 U. 2:43:13 AM 05/0... 245:27 AM... 2:45:29 AM... . 245:.11,AM..... SSF SSF __SSi_ 13914m 13.025m 2'J 27.2E5m 14.5S3m 2 EG:' 2241th 144B3m 7K v < 3 I Display yjAuto Reveal | yAuto Zoom J yj Save viewpoint ;iHghtqht4f § Name: E-Powr-Cabl Type: Cable Tray •Item 2 iNameAWat Type: "Wall floor final as on Feb 05.nwd BlE -Powr-Cabl 1 9 Cable Tray 0Kghtcht y e3 6th floor Final as on Feb 05.nwd B f A-Wall 9 Wall 0 Highlight CD V Ready • fi .98 MB Figure 5.26: A Typical Approved Clash for Sixth Floor Level for 5.5.3.5 A Typical Active Clash for this floor level is as shown below: 117 Batch Rules Select Results ; Report Name Status S Dista Description Found Approved : Approved By i Clash Point IA ii display s 1 1 * Clashl2 • Clash21 • Ctash22 • n a * M Active Active [Active Active 0.071m 0.138m v] 0.141m (I Ififm 3 S a e 10:48:02 AM 157... 10:48:02 AM 157... 10:48:02 AM 157... 114802 AM 15/ 18.441m 14.765m 2.736I'! 16.593m 14 765m 2763 | 18.661m 14 765m 2.804. (, 1R5R6m 14 765m 2 7 7 6 ^ '.. Seed Fitter A VAjto Reveai ViAuto Zoom yjSave Viewport J <l ' > HBciHahtM v tern 1 Name: E-PowrCabl Type: Cable Tray Name MHVACHotw-Pipe Type: Pipe 6th floor Final as on Feb 05.nwd B l E-Powr-Cabl 0 Cable Tray A . V 6th floor Final as on Feb 05.nwd eSM-HVAC-Hotw-Pipe OPipe A 0 Highlight | Select I 0Hghfght [Select ] I Figure 5.27: A Typical Active Clash for Sixth Floor Level for 5.5.3.5 • 2" Floor Corridor: This is test resulted in a total of 41 clashes out of which 26 clashes are being given approved status. Although these 26 clashes interfere with the vertical space around the cable tray but then these clashes are on the lower side of the cable tray and this constraint is for the top side of the cable tray as seen below: 118 Name : Status Dista. ; Description Found Approved i Approved By : Oash Point IAN Display' - I •Clash3 Approved -0.016m Clearance 1 29:54 PM 2FJ/T... 1:30:45PM. SSF 10.944m 34 123m 7.55! I • Oash4 * P r J ^ v e d -0.015m Clearance 1 29:54 PM 26/1... 1:30:48 PM. SSF 10.944m 33 923m 7.551 | « Ossh6 Approved iv]-0002m Clearance 1:29:54PM28/1... 1:32:03PM. SSF 10944m 34.275m 755V V jSHect F*er 3 yjAuto Reveal jii ifsJlAyto Zoom V'Save Viewpoint < • - - - - _ - . . . . . "' _ : !»i i r i H i q h t a h t A I SJ lem 1 Name 2nd Floor • Cable and Cond Type Cable Tray 1 Name: ES Pipe same as Cold water Type: Pipe B @ May 19-2M5tfattorm-2nd after malhnov27.nwd UJ S S 2nd Floor - Cable and Cond fi> Cable Trav | 3 highlight j Select | B|s] May 19-2005 platform- 2nd atter math nov 27,nwd BM 2nd floor Plumbing 0 E S Pipe same as Cold water 3 HigMght y V | Select | Figure 5.28: A Typical Approved Clash for Second Floor Corridor Area for 5.5.3.5 The remaining 15 clashes are being given active status as the cable tray passes through a device which is a component of Electrical Lite Ceiling on the same level and this clash needs to be resolved with due consultation with the respective consultant and the sub trade as this will not allow the future access to the cables in some area of the cable tray. If the sub trades and consultants feel that this could be neglected then the model is in compliance with this constraint. A typical active clash is as seen below: 119 » 0 X , . fl,.,.„.,.,..,,... Batch Rules Selec Kesuls Report Name Status Dista.. Description Found .Approved Approve d By aash Port A Display 1 • Oash.1 Active $.m Oearance 2.55:54 AM 25,1.. 15.573m J2 533m 7.482m •Select filter A #Qash2 Active v|-0.1SJ4m Qearance 2:55:54 AM 25/1... 11144m 32.844m 7.550m ! g fc to Reveal • | #Qash5 7Btive -0.005m Qearance 2:55:54 AM 211... 15.433m 33.015m 7.425m V 1/AutoZoom V • i irtiri MI v.i n rn ir HI pnr 1 T M L ' tan 1 - • , Name: 2nd Floor • Cable and Cond Type: Cable Tray --tan 2 1 Name: 2nd Floor E-lie-Qng Type: Device FJ§ May 19-2005 platform- 2nd after matJufwg ; A B i 2nd Floor-Cable and Cond 0 Cable Trav v B Height Select | B g May 19-2005 platform- 2nd after matfidwg j A ] if 2nd Floor E-Lite-CIng fJDevice lil BWgHght Q Figure 5.29: A Typical Active Clash for Second Floor Corridor Area for 5.5.3.5 • Main Floor: This test resulted in a total of 21 clashes of which 17 has been given an approved status and 4 has to be resolved. The approved clash for this constraint on this floor level is as shown below: 120 H Main Floor Final on Feb 05 - NavisWorks JetStream (Not for Resale) Fte gt&t View Viewpoint Review Tools Help Q <a a* £ s# H ?d « " » i - S t ^ « 1 88 *J -4 • «9 <bj * H Q •Sen Ruies |; Select Results R e p o rt • Name Status Dista Description Found .Approved Approved By Oash Pont • C M i l Approved A •0224m Oearance 1 56 16AM JuV'l... 4 38:47 AM. SSF 15.764m 30.964m 3.150m • C!ash2 .Active -0.041m Gearance 1:5616AM 30/1... 14967a 24.415m 3.215m < J _ _____ > Display [•Select F t e r 3 jyiAuto Reveai lyrlAuto Zoom I iy»]Save viewport , item i Name: E-Powr-Cabl Type: Cable Tray lem 2 Name: Main Root -A-Wall Type: Wall Ef@Main Floor Final on Feb 05.nwd BSE-Powr-Cabl 0 Cable Trav 0 Highlight B § Main Floor Final on Feb 05.nwd BS Main Floor-A-Wall L a Wall Select | B Highlight v | Select | Figure 5.30: A Typical Approved Clash for Main Floor Corridor Area for 5.5.3.5 The clash which is active for this constraint on this floor level which needs discussion with the consultants and the sub trades is as shown below: 121 . Batch Rdes Selectj e^sjfts Region Name Status Dista. : Descnption Found \ Approved i Approved By | dash Point Daplay Clashl Resolved -0.224m Oearance 3:22:44 PM 30/1... 15.7&4m 30 964m 3.150m • Qash2 Active "vi -0041m Oearance 3:22:44PM30/1... 14.967m 24 415m 3215m Selea Filter A iSiAUo Revea! V.Auto Zoom | v • l e m l , rhn2 -• Name: E-PoAT-Cabl Type: Cable Tray :Name: Main Roor-M-Sanr-Ppe-Vent Type: Pipe B § May 20-2005 platform- mainfloor aftermath-no interterence.nwd * B l E-Powr-CaW fll Cable Trav v B Highlight [Select ! BQ May 20-2005 platform- mainfloor aftermatft-no interference-nwd I A B3f Main floor-M-Sanr-Plpe-Vent eiPipe v 0 Highly ["5e7 Figure 5.31: A Typical Active Clash for Main Floor Corridor Area for 5.5.3.5 5.5.3.6. The Cable Tray has to maintain a 15cm vertical clearance zone anywhere on the top side Test Name: Cable Tray should maintain a 15cm vertical clearance zone anywhere on the top side. Test Description: This constraint governs the vertical clearance for the cable trays for future access. In NavisWorks, there is no in-built functionality that enables the user to just check for the clashes in a particular side (in this case top side of the cable tray), so I had to manually review all the resulting clashes and check for those positioned above in the zone of clearance which has to be reported as an active clash. Rules: We are ignoring clashes between the following for this test-• Items in the same layer • Items in the same group/block/cell • Items in the same composite object • Items in previously found pair of composite objects • Items with coincident snap points 122 Selecting Items for clash testing: For this test, we are going to test all the Cable Trays in the floor level against all the components in the floor level for a clearance clash and we are not including any self intersection among the components. The tolerance limit we are keeping for this clash test is 0.15m. Clash Results: • 5th Floor: There are no cable trays in the Fifth Floor Level so this test is redundant for this area. th • 6 Floor: This test resulted in a total of 22 clashes and 19 with respect to the horizontal clearance between the cable tray and the other component in the floor level so all of them have been give a status of approved. A typical approved clash for this constraint on this floor level is as below: 3 6th floor Final as on Feb 05 • NavisWorks JetStream (Hot for Resale) Ne Edt View Viewpoint Review Toote Help Vj ^ ffl V§ «3 "Q, f) Q «D ft 1} | » « » Cfc? »». 8 o l - €> Select i Results , Report i Name • Clash 1 Cash 2 • Cteh3 < Status \ Dista.. \ Descrption Found Approved Approved By .Approved 0.000m Clearance 2:59:12 AM 05/0.. 3:00:40 AM... SSF Approved 0.000m Clearance 2:59:12 AM 05/0... 3:00:45AM... SSF Approved Qo.OO&r, Clearance 2:53:12AM05/0... 3:03:47AM... SSF AnnT'Vert OimWt Oaranne ?:59T? AM J5/ ! i J J M S A M S S F Dash Point A ; 14.SS5m 14.565m 2 £5 17.320m 14.965m 2.601 17.320m 14 965m 2.601, 18691m 149fiSm 2 7 4 : v | _ J Display PSetedF»w j igAuto Reveal f '•i Auto Zoom yiSave viewport 'riHohttrtAI Name: E-Powr-Cabl Type: Cable Tray • lent 2 Ham: Mm Type: Wall 6th Hoor Final as on Feb 05.nwd A B i E-Powr-Cabl gCab teTray 1 0Hgh«9« [Select | B § 6th floor Final as on Feb 05.nwd : A B i A - W a l l L g w a i i § BHishlght Ready Figure 5.32: A Typical Approved Clash for Sixth Floor Level for 5.5.3.6 A typical active clash is as shown below: 123 Bat* Rules % Sded Results Report Name Status Dista. Descnption Found Approved Approved By dash Port i*J \l?^ ,:::zzz:r'" #Oash1l * Clash 12 * Clash 14 * ClashP. ; Active A c t i v e " Active ArtnrnveH 7j 0064m 0071m 0091m n.nrsm.. Qearance Oearance Qearance nftarflnnft 10:48:09 AM 15/. 10:48:09 AM 15/ 10:48:09 AM 15/ 1IUJIN AM. IV. 1?:1R-4GP SSF 16.793m 14 M5m 2 73: '• Select filter A 18 441m 1476Sn 273J * A l o Reveal 13695m 12 33m 274. !"JAu!oZoom ?7?fiV> 14 « V . 7 « v * ^ V « W <l [>J ! | IHolttt/* IM| <• lem 1 tmZ iName; E-Powr-Cabi Type. CaWe Tray l3J^6tft floor Final as on march 15.nwd BgE-Powr-Cabl ©Cable Tray Highlight Name M-HVAC-Hohv-Pipe Type: P£°e Bgetti floor Final as on march 15.nwd N OSM-HVAC-Holw-Pipe ' 9 Pipe y | Select | : 0Hghight | Select | Figure 5.33: A Typical Active Clash for Sixth Floor Level for 5.5.3.6 2" Floor Corridor: This test resulted in a total of 6 clashes out of which 4 clashes are being given approved status. Although these 4 clashes interfere with the vertical space around the cable tray, these clashes are on the lower side of the cable tray as shown below and this constraint is for the top side of the cable tray. The remaining 2 clashes are being given active status as the cable tray passes through a device which is a component of an electrical lite ceiling on the same level and this clash needs to be resolved with due consultation with the respective consultant and the sub trade as this will not allow the future access to the cables in some area of the cable tray. This active clash is the same as shown below: 124 Bach Rules Satat Results Report: Name Status Dista.. Description Found Approved Approved By Dash Point A # Dash2 • QashS A M in Active Active -0.120M v j -0104m *"' -0.005m Clearance Clearance Qearance 2:59:54 AM 29/1... 2:5954 AM 29/1... 25954 AM 29/1... 15.673m 32.535m 74§2m 11.114m 32.844m 7.55!h 15.483m 33.015m 7.425m f—' V vjAuto Reveal gAulo Zoom "rill: " tem 2 Name: 2nd flocf - Cable and Cond Type: Cable Tray S @ May 19-2005 platform- 2nd after math.rJwg A B l 2nd Floor- Cable and Cond —9 Cable Trav Vi 0 Highlight [Sejed"| Name: 2nd Roor E-bte-Qng 'Type: Device B@ia7l9-2005 platform- 2nd after mathdwg~ B i 2nd Floor E-Ute-Ctng 0 Device i Figure 5.34: A Typical Active Clash for Second Floor Corridor Area for 5.5.3.6 • Main Floor: This test resulted in a total of 10 clashes of which 9 have been given an approved status while the one that needs to be resolved is as shown below: 125 Rules Select! ResuKs Report Name I Status 1 Dista... Description Found .Approved Approved By Clash Point Display Cashl ft 0ash2 Resolved i Active -0.224m Oearance 3:22:44 PM 3C J] -0.041m Clearance 322:44 PM 3Q /I... /I... 15.764m 30.%4m 1150m 14.963a 24.415m 3.215m : ^Select Filter y!Auto Reveal M V-.AutD Zoom r~j lem 1 Name E-&owr-Cabi Type: Cable Tray lem 2 Name Main Roor-M-Sam-Pipe-Vent Type Pipe B[d] May 20-2005 platform- mainfloor aftermath-no interterence.nwd B l E-Powr-CaM S Cable Trav GrjHgUdlt 8 § May 20-2005 platlorm- mainfloor aftermath-no interterence.nwd B3f Main Floor-M-Sanr-Pipe-Vent 1 OPipe [Select 1 BHigNigti [ Select | Figure 5.35: A Typical Active Clash for Main Floor Corridor Area for 5.5.3.6 5.5.3.7. The required clearance between heating water supply and return lines is 6 in. Test Name: The required clearance between heating water supply and return lines is 6 in. Test Description: This constraint is for checking the clearance between heating water return and supply lines. For this constraint, the clearance value shall be 6 in. or 15 cm. Rules: We are ignoring clashes between the following for this test-• Items in the same layer • Items in the same group/block/cell • Items in the same composite object • Items in previously found pair of composite objects • Items with coincident snap points Selecting Items for clash testing: For this test, we are going to test the heating water return lines in the floor level against the heating water supply line in the floor level for a clearance clash and we are not including any self intersection among the components. The tolerance limit we are keeping for this clash test is 0.015m. 126 Clash Results: • 5th Floor: This Test resulted in Zero Clashes. • 6th Floor: This Test resulted in Zero Clashes. • Main Floor Corridor: This Test resulted in Zero Clashes. • 2nd Floor Corridor: This Test resulted in Zero Clashes. 5.5.4. Summary of Results from Constraint Based Modeling in NavisWorks Of the 27 design, modeling or position related constraints that have been identified in the past studies; I could model only 7 in NavisWorks. After analyzing these 7 component-clearance related constraints in NavisWorks, I conclude that NavisWorks gives a more intrinsic and detailed review of the clashes that one might encounter in a MEP system. The summary of clashes detected in my review of the UBC Chem Bio Project using NavisWorks is in Table 5.3. A detailed report of all the active clashes generated for all the tests run on the floor areas in NavisWorks is enclosed in a Compact Diskette (CD) which contains the NavisWorks Drawing File (.nwd) for the 5th floor, 6th floor, Main floor corridor and 2nd floor corridor levels. 127 Constraint Type Floor Area . ' Type of Clash , : : " ^ § ^ Active Approved Total -Physical Interferences 5th Floor 48 417 465 6th Floor 32 153 185 2nd Floor Corridor 9 27 36 Main Floor Corridor 17 190 207 Sub-Total 106 787 893 Mechanical Constraints 5th Floor 0 14 14 6th Floor 0 0 0 2nd Floor Corridor 0 0 0 Main Floor Corridor 13 6 19 Sub-Total 13 20 33 Plumbing Constraints 5th Floor 8 198 206 6th Floor 6 129 135 2nd Floor Corridor 0 0 0 Main Floor Corridor 2 167 169 Sub-Total 16 494 510 Electrical Constraints 5th Floor 0 0 0 6th Floor 13 122 135 2nd Floor Corridor 21 80 101 Main Floor Corridor 6 71 77 Sub-Total 40 273 313 Grand Total 175 1574 1749 Table 5.3: Summary of Clashes Detected using NavisWorks with respect to type of system From the above table we can deduce that the total number of clashes identified in the UBC Chem Bio Project for the 7 clearance related constraints governing the MEP coordination process and one overall hard conflict test/physical interferences using NavisWorks is 1749. However, we need to focus more on the active clashes as those are the clashes that were left undetected in the earlier study by Tabesh and Staub-French (2005) and might have resulted into a field conflict. The total number of active clashes for the constraints modeled in NavisWorks is 175. However, one must note that out of these 175 clashes there might be duplicity in some of them and hence the total number will be a little less than 175. 128 For the 5 floor typical lab, the area where Tabesh and Staub-French more concentrated their study, I detected approximately 56 active conflicts that violate the governing constraints or are hard physical conflicts. However, since the project was already nearing completion while I started with my work, I cannot comment on how many of the clashes that I have recorded in my analysis actually resulted in a field conflict. If all of these conflicts that I detected resulted in a field conflict, i.e. were detected on the field, then they would have huge effect on the cost, time and productivity of the project and this has been discussed in more detail in the next Chapter. As there was limited knowledge available on the type of conflicts / interferences resulting from these governing constraints and I developed good knowledge on the types of the conflicts resulting from these constraints through my analysis, it was necessary to correlate these constraints with the type of conflicts so that in future projects, the project participants get a fair idea of what types of conflicts are generated by implementing these design, modeling and positioning constraint on the MEP Systems on a project. This has been discussed in the next section in context with the previous frameworks and classifications done by Tatum and Korman (2001), Riley et al. (2005) and Tabesh and Staub-French (2005). To summarize, I can say that NavisWorks is a better tool for conflict detection and management in comparison ABS as one can not only do constraint based conflict detection but also have a better view of the details of the conflicts in the MEP Systems. 5.6. Classification of Conflicts / Clashes / Interferences 5.6.1. Introduction As a part of analyzing the knowledge obtained from observing experts during coordination meetings and other sources, Tatum and Korman (2001) identified and classified the five most common types of interferences found in MEP coordination. Table 5.4 defines these interferences. 129 Sr. No. Interference Type : D'escriptioirW; 1 Actual An actual (physical) interference occurs when two or more components physically interfere. 2 Extended An extended interference occurs when a component interferes with an extended space that is associated with another component. 3 Functional A functional interference occurs engineers position two or more components such that their location in relation to each other jeopardizes the intended function of the component. 4 Temporal Time-related interferences occur when engineers position components in a manner that prevents efficient construction sequencing and scheduling. 5 Future A future interference occurs when engineers position components in locations that they do not allow space for routine operations and maintenance tasks or space for future expansion. Table 5.4: Type and description of interferences identified by Tatum and Korman (2001) In addition to this classification, Riley et al. (2005) gave their own classification for interferences based on the time they were identified in the project, the same as given in Table 5.5. Sr. No. Type of Coordination Conflict Description Severity of Impact Timing of Occurrence Percentage with respect to Total Conflicts in a , Project 1 Type 1 Detected and resolved before installation has begun. Start of work is potentially delayed, redesign is required. Typically occur when project is 5-15% complete Approx. 50% 2 Type 2 Detected after Trade 1 has completed work, Trade 2 forced to reroute work. Trade 2: Disrupted and potential redesign and fabrication changes are required. Typically occur when project is 15-50% complete Approx. 33% 3 Type 3 Detected after Trade 1 has completed work, Trade 2 forced to wait until Trade 1 moves work. Trade 1: Disrupted, rework, and redesign required. Trade 2: Delayed. Typically occur when project is 60-80% complete Approx. 17% Table 5.5: Types of coordination conflicts, timing of detection, and severity of impact 130 The above two classifications were really useful to me for understanding the types of conflicts that generally occur in the MEP coordination process. However, the classification defined by Riley et al. (2005), gives us a more crude result as it is more dependant on the timing of coordination which will vary from project to project i.e. if the coordination is done early and in the right manner then the most of the resulting conflicts will be classified under the Types 1 & 2 with very little under Type 3 whereas if there is no or little coordination on the project then most of the conflicts will be of the Type 3. This classification is not helpful for linking the governing constraints with the type of conflict it results in but is useful for estimating the MEP coordination costs and productivity impacts, the same has been discussed more in detail in the next chapter. The classification by Tatum and Korman (2001), gives us a more comprehensive insight into the type of coordination conflicts and I have used this classification to bridge the gap between the conflicts that generally occur in the MEP coordination process and the constraints that govern them. In addition to the types mentioned in Table 5.4,1 found that some of the interferences were as a1 result of the missing details in the drawings or due to error in the design and hence I felt there should be 2 more additions to the types of the interferences identified by Tatum and Korman i.e. Design error and Drawing error and these can be defined as: • Design Error: Design error interference occurs when the engineers find out that the designer has overseen certain details required for the design and has either under / over designed the component. This type of error generally requires a re-design on the part of the designer to rectify the error in the design and potentially delays the work by the trades. This interference has huge impact on productivity and resulting cost of the field conflict. For example, if the entire ductwork has been fabricated and brought to the site to be installed only to be found that the space requirements are not met, then the entire duct work needs to be re-designed and re-fabricated thus resulting in huge cost and productivity impacts on the project. • Drawing Error: Drawing error interference occurs when the engineers find out that the Issued for Construction (IFC) drawings lack some detailing with respect to the installation or position of the component being installed in that particular location. 131 5.6.2. Relation between the Types of Conflicts and MEP Constraints Tabesh and Staub-French (2005) had classified the constraints they had enlisted in their work with respect to the knowledge domains, attributes and modeling and coordination tasks that are key in the MEP coordination process. However, they failed to correlate these constraints with the interferences they identified and classify the constraints / conflicts based on the types of interferences defined by Tatum and Korman (See Table 5.4) or Riley (See Table 5.5). The failure to classify the conflicts resulted in some amount of ambiguity with the type of interferences these identified conflicts represent. In addition to this, there was no correlation between the conflicts and the constraints governing them i.e. although they documented the conflicts and the constraints, there was no clear emphasis on what constraints are governing the conflicts identified in the project. I undertook this task of classifying the conflicts with respect to the type they represent and the same has been given in the Table 5.6. 132 Sr.No. Description of Interference -11, ' Interfering Components Interference Type ;f. B 1 Chilled Water/ Heat Recovery Line had to be moved to the roof because of lack of space. CW/HR Supply Duct Actual, Functional & Extended 2 Floating ceiling elevation was lowered to provide more service space. Floating Ceiling MEP components Extended 3 Cable Tray was moved near the wall to provide the necessary horizontal clearance. Cable Tray Supply Duct Future 4 Cable Tray had to shift elevation in its layout to provide the vertical clearance. Cable Tray Pipes & Doors Future 5 The rain-storm water pipe run was redundant as it was discontinued at the lower floor. RWD pipe N/A Actual 6 Location and dimensions of the slab opening was modified to provide the vertical passage of the MEP systems. Slab Openings Vertical Pips Stacks Actual, Extended and Functional 7 The designed trim in the concrete beam was not necessary. We changed the design to cancel the trim. Concrete Beam N/A Actual & Design Error 8 Missing pipe sizes in the plumbing drawings were identified and addressed, which helped to clarify and reduce RFI's. Pipes (no data) Drawing • Error 9 Dimension and location of the slab opening on th 6 floor slab (for the electrical room) was modified, and another opening was added. Conduits Slab Openings Actual & Functional 10 The floor drain and the related sanitary line located in Room 516 were mistakenly discontinued. Sanitary pipe N/A Actual & Design Error 11 The ventilation of acid neutralizers was added because there was no ventilation in the 2D design drawings. Equipments N/A Design Error, Functional & Future 12 Sizes of the sanitary pipes for fume-hood and sinks: it was not designed in the schematic drawings. Sanitary Pipes N/A Actual & Design Error 13 The drawings lacked the layout of conduits in the labs. The layout of Exhaust ducts had to change in the model to avoid interference. Conduits Exhaust duct / diffusers Actual, Extended, Future & Design Error 14 Due to the slope of the slab, the available service space had less height than assumed. Layout of the ductwork was changed. Ducts Sloped Roof Slab Actual, Functional, Extended & Future 15 Originally, pipes were designed to be installed above the ducts. This order and sequence was reversed. Ducts HW pipe & HR/CW pipe Temporal, Extended & Future 16 The conduits interfere with the duct and block the diffusers. The layout of ducts and positioning of diffusers was changed. Diffusers & Ducts Conduits Actual, . Extended & Functional Table 5.6: Classification of Interferences identified by Tabesh and Staub-French in their study (2005) 133 The above table just represents the conflicts that Tabesh and Staub-French identified in their study. Based on the components involved in the conflict and the nature of the conflict (for example, in case of Conflict #16 in the Table 5.5, the conduits interfere with the duct, this is an actual interference while it also blocks the diffusers, this is a functional interference as by blocking the diffusers, the functioning of the ducts gets affected and this has occurred as the conduits are within the extended space of these ducts and hence this conflict is also an extended type of interference), I have classified these conflicts with respect to the classification on the types of interferences by Tatum and Korman (2001). The above classification of conflicts thus gives us a fair idea on what types of conflicts generally occur in the MEP coordination process but it is tough to classify each and every conflict that has been detected on the project. For example, in my review of the UBC Chem Bio Project using NavisWorks, I have identified approximately 175 active clashes for the various governing constraints, and to classify each and every one of them will be a difficult task. Also, it's not these conflicts identified that are common to the various projects wherein MEP systems are in place, the common thread are the constraints that govern these MEP systems i.e. the constraints that generate these conflicts and hence correlating these constraints with the resulting type of conflict is very important. This correlation will increase the knowledge for the MEP coordination as it will be easier for the project participants to understand the type of conflicts they are actually seeing while coordinating these MEP systems and thus reduces the ambiguity in the nature of these conflicts. Based on the active clashes that each of these constraints modeled in NavisWorks resulted in (Section 5.5.3) and the knowledge on types of clashes, the constraints that weren't modeled could result in, I have classified the constraints based on the resulting type of interference(s) they might result in the designing, modeling and/or construction stage of the MEP coordination process and the same has been illustrated by me in the table 5.7 for the constraints that were identified/documented in the studies done by Tatum and Korman (2003) and Tabesh and Staub-French (2005). 134 Sr. No,' : System Constraint Description Analyzed in NavisWorks (Yes /No) Resulting Type of Interference(s) 1 Mechanical The ducts should maintain a minimum clearance trom me adjacent walls and slabs. Yes Actual 2 Mechanical The ducts, needing the largest supports, should be positioned closer to the slab. No Temporal 3 Mechanical In case of external insulation of equipment, positioning should account for installation space. No Actual, Extended 4 Mechanical The code implies the thickness of the duct's external insulation or internal lining. No Functional 5 Mechanical The minimum standard radius of a round Fitting elbow can not be less than its diameter. No Functional 6 Mechanical It is better to install the ducts first, due to their size and inflexibility. No Temporal 7 Mechanical Insulation thickness required for heating water supply lines is IVi in. No Functional 8 Mechanical Installation of air terminal boxes always precedes air distribution ducts to zone No Functional, Temporal 9 Plumbing U-shaped over passing creates air traps in pressure pipes; Avoid them. No Functional 10 Plumbing The RWD line can not run bellow the false-ceiling elevation. Yes Actual 11 Plumbing In assigning space to pipes^  should account for installing insulation. No Extended 12 Plumbing Pipes have higher maintenance frequency than ducts; therefore they should not be positioned above the ducts. Yes Actual, Temporal, Future 13 Plumbing RWD pipes should maintain a 1% minimum slope. No Functional 14 Plumbing The minimum standard radius of a round fitting elbow can not be less than its diameter. No Functional 15 Plumbing The code implies the thickness of the insulation around the pipe. No Functional 16 Plumbing The placeholder used to hold a 4" vertical stack pipe in a wall, will need at least a 7" wall No Functional 17 Plumbing The RWD routing should connect the vertical stacks of the adjacent floors. No Actual, Functional 18 Plumbing All Waste/Sanitary Drain stacks have to be connected to the vent stacks going up from that floor. No Actual, Functional 19 Plumbing Required Clearance between Heating Water Supply and Heating Water Return Lines is 6 in. Yes Actual, Extended and Functional 20 Plumbing Gravity Driven Wastewater drain lines should slope 1/8 in. per foot No Functional 21 Plumbing Access Space required by personnel for valves is typically 12 in., depending on the type of valve No Extended, Future 22 Electrical The cable tray has to maintain a 60 cm horizontal clearance on one side to provide access to cables. Yes Actual, Extended and Future 23 Electrical The cable tray has to maintain a 30 cm vertical clearance on top side to provide future accessibility to cables. Yes Actual, Extended and Future 24 Electrical The cable tray has to maintain a 15 cm vertical clearance zone anywhere on top side. Yes Actual, Extended and Future 25 Electrical The number of maximum 90 degree elbows from start to finish for a conduit is four: No Functional 26 Electrical Pulling Electrical Cables requires 5 ft. of access space from the end of the conduit No Extended, Future 27 Electrical Electrical conduit may rest on pipe racks that contractors attach to walls or hang from trapeze hangers No Actual, Functional and Future Table 5.7: Classification of Constraints with respect to the Type of Interference(s) they result in 5.7. Conclusion From the above study, I conclude that NavisWorks is a more robust and sophisticated tool than ABS as it gives the user a more intrinsic and detailed look on the clashes and the constraints governing the MEP Systems that are present in the floor level (7 detected 175 active clashes for the same amount of floor area that was studied by Tabeesh and Staub-French wherein they had detected I reported only 50). Also, NavisWorks is a better tool in terms of conflict management as one can generate reports of every test that has been run on the floor area and thus helps in a better handling of the conflicts while discussing the same in the MEP coordination meetings. For the constraints that I could not simulate / test for in NavisWorks, we need a more sophisticated tool than NavisWorks which can help us simulating those constraints and detecting the conflicts related to those constraints in the MEP systems. The correlation created between the constraints and the type of conflicts they result in, is very useful in terms of understanding what will be the frequently occurring conflict due to a specific constraint. For a project, the most detrimental is the Type 3 field conflict as it can result in huge loss in terms of finance and productivity so they should be tried to be best avoided i.e. one should do an early and high level of MEP Coordination in a project. The detailed summary of classification in conjunction with the classification done by Tabesh and Staub-French (2005) for the constraints is given in Table 5.8. (Note: the values of the table in bold represent the additions I have made to the classification done by Tabesh and Staub-French (2005)). Thus we can say that for the current list of constraints that have been documented to date by the researchers, its relation with the type of interference it can result in is complete from all aspects. The unresolved conflicts from Tabesh and Staub-French's (2005) work and the active clashes I found in my analysis will have a detrimental effect on the level of coordination on the project, MEP coordination costs and overall project productivity and this impact has been discussed in the next chapter. 136 | System 1 Modeling and Coordination Constraints Knowledge Domain Tabesh's Knowledge Attribute Modeling & Coordination task Korman's Knowledge attribute Resulting Type of ; Interference(s) . 1 T h e d u c t s s h o u l d m a i n t a i n a m i n i m u m c l e a r a n c e f r o m t h e a d j a c e n t w a l l s a n d s l a b s . C o n s t r u c t i o n T o l e r a n c e s R o u t i n g C l e a r a n c e Actual 2 T h e d u c t s , n e e d i n g t h e l a r g e s t s u p p o r t s , s h o u l d b e p o s i t i o n e d c l o s e r t o t h e s l a b . C o n s t r u c t i o n P r o d u c t i v i t y S u p p o r t S y s t e m Temporal n o 3 In c a s e of e x t e r n a l i n s u l a t i o n of e q u i p m e n t , p o s i t i o n i n g s h o u l d a c c o u n t f o r i n s t a l l a t i o n s p a c e . C o n s t r u c t i o n I n s t a l l a t i o n S p a c e P o s i t i o n i n g I n s u l a t i o n I n s t a l l a t i o n S p a c e Actual, Extended 'c 4 T h e c o d e i m p l i e s t h e t h i c k n e s s of t h e d u c t ' s e x t e r n a l i n s u l a t i o n o r i n t e r n a l l i n i n q • D e s i q n P e r f o r m a n c e I n s u l a t i o n Functional SZ U 5 T h e m i n i m u m s t a n d a r d r a d i u s of a r o u n d f i t t ing e l b o w c a n n o t b e l e s s t h a n its d i a m e t e r . O p e r a t i o n P e r f o r m a n c e D e t a i l i n g Functional C o n s t r u c t i o n F a b r i c a t i o n 6 It i s b e t t e r to i n s t a l l t h e d u c t s f i rs t , d u e to t h e i r s i z e a n d in f l ex ib i l i t y . C o n s t r u c t i o n P r o d u c t i v i t y S e q u e n c i n g S e q u e n c e Temporal 7 Insulation thickness required for heating water supply lines is VA in. Design Performance Detailing Insulation Functional 8 Installation of air terminal boxes always precedes air distribution ducts to zone Construction Productivity Sequencing Sequence Functional, Temporal 9 U - s h a p e d o v e r p a s s i n g c r e a t e s a i r t r a p s in p r e s s u r e p i p e s ; A v o i d t h e m . O p e r a t i o n P e r f o r m a n c e 'Functional 10 T h e R W D l i n e c a n n o t r u n b e l l o w t h e f a l s e - c e i l i n g e l e v a t i o n . D e s i g n A e s t h e t i c s Actual 11 In a s s i g n i n g s p a c e to p i p e s , s h o u l d a c c o u n t f o r i n s t a l l i n g i n s u l a t i o n . C o n s t r u c t i o n I n s t a l l a t i o n S p a c e R o u t i n g I n s u l a t i o n I n s t a l l a t i o n S p a c e • Extended x cn c 1 2 P i p e s h a v e h i g h e r m a i n t e n a n c e f r e q u e n c y t h a n d u c t s ; t h e r e f o r e t h e y s h o u l d n o t b e p o s i t i o n e d a b o v e t h e d u c t s . O p e r a t i o n A c c e s s A c c e s s S e q u e n c e Actual, Temporal, Future ' • . h_ 1 3 R W D p i p e s s h o u l d m a i n t a i n a 1 % m i n i m u m s l o p e . D e s i g n P e r f o r m a n c e S l o p e Functional tn (0 <u 14 T h e m i n i m u m s t a n d a r d r a d i u s o f a r o u n d f i t t ing e l b o w c a n n o t b e l e s s t h a n its d i a m e t e r . O p e r a t i o n P e r f o r m a n c e Functional o o C o n s t r u c t i o n F a b r i c a t i o n D e t a i l i n g Cu 1 5 T h e c o d e i m p l i e s t h e t h i c k n e s s of t h e i n s u l a t i o n a r o u n d t h e p i p e . D e s i g n P e r f o r m a n c e I n s u l a t i o n Functional CD c 1 6 T h e p l a c e h o l d e r u s e d to h o l d a 4" v e r t i c a l s t a c k p i p e in a w a l l , w i l l n e e d a t l e a s t a 7" w a l l C o n s t r u c t i o n V a r i a n c e Functional £ 1 7 T h e R W D r o u t i n g s h o u l d c o n n e c t t h e v e r t i c a l s t a c k s of t h e a d j a c e n t f l o o r s . D e s i g n F u n c t i o n V a l i d a t i n g D e s i g n F u n c t i o n Actual. Functional E 1 8 A l l W a s t e / S a n i t a r y D r a i n s t a c k s h a v e to b e c o n n e c t e d t o t h e v e n t s t a c k s g o i n g u p f r o m tha t f l o o r . D e s i g n P e r f o r m a n c e S y s t e m / F u n c t i o n Actual, Functional 1 9 R e q u i r e d C l e a r a n c e b e t w e e n H e a t i n g W a t e r S u p p l y a n d H e a t i n g W a t e r R e t u r n L i n e s i s 6 i n . C o n s t r u c t i o n T o l e r a n c e s R o u t i n g C l e a r a n c e Actual, Extended and Functional 2 0 Gravity Driven Wastewater drain lines should slope 1/8 in. per foot Design Performance Routing Slope Functional 21 A c c e s s Space required by personnel for valves is typically 12 in., dependinq on the type of valve Operation Access Routing Access Clearance Extended, Future 2 2 T h e c a b l e t r a y h a s to m a i n t a i n a 60 c m h o r i z o n t a l c l e a r a n c e o n o n e s i d e to p r o v i d e a c c e s s to c a b l e s . O p e r a t i o n A c c e s s A c c e s s C l e a r a n c e Actual, Extended and C o n s t r u c t i o n I n s t a l l a t i o n S p a c e Future "TO o 23 T h e c a b l e t r a y h a s to m a i n t a i n a 30 c m v e r t i c a l c l e a r a n c e o n t o p s i d e to p r o v i d e f u t u r e a c c e s s i b i l i t y to c a b l e s . O p e r a t i o n A c c e s s L a y o u t A c c e s s C l e a r a n c e Actual; Extended and Future ectri C o n s t r u c t i o n I n s t a l l a t i o n S p a c e LU 24 T h e c a b l e t r a y h a s t o m a i n t a i n a 1 5 c m v e r t i c a l c l e a r a n c e z o n e a n y w h e r e o n t o p s i d e . O p e r a t i o n S a f e t y P e r f o r m a n c e C l e a r a n c e Actual, Extended and 25 T h e n u m b e r o f m a x i m u m 90 d e g r e e e l b o w s f r o m s t a r t to f i n i s h fo r a c o n d u i t is fou r . O p e r a t i o n P e r f o r m a n c e R o u t i n g Functional 2 6 Pulling Electrical Cables requires 5 ft. of access space from the end of the conduit Construction Access Routing Access Clearance -- 'Extended, Future 2 7 Electrical conduit may rest on pipe racks that contractors attach to walls or hang from trapeze hangers I I t 11 1 P ^.8' ( 11 i l <: C l f l ( ' ' l t i *»Tl i\f ( V i t u + r - o ! . . t n 1... < 1 V 1.. -1 f \ • i . . . Construction Productivity Routing Support System • Actual, Functional and Future and Resulting Type of Interference Chapter 6: Inter-relationship of Conflicts with Project Costs and Productivity 6.1. Background Design coordination is a key to reducing uncertainty in production processes on building projects. Field conflicts that result from interfering systems are an avoidable source of production disruptions. The risk of interference problems is highest on building projects that have intense mechanical, electrical, and plumbing (MEP) requirements. Production risks are compounded, as schedules become more intense. Eliminating coordination problems can be characterized as a prerequisite to the start of construction work on intense projects with dense MEP system requirements. Fast pace and mechanically intensive facilities such as data-centers, hospitals, and laboratories typically require the most intense coordination efforts. In the study on MEP cost as a percentage of total building cost, Tao et al. (2001) stated that there is a huge variation on the M E P cost for various types of projects that generally cater to high M E P coordination. The same i is illustrated in Table 6.1. Facility Type MEP Cost as a percentage of Total Building Cost High Medium Low Semiconductor Plants 60 50 40 Biotechnology Plants 65 55 45 Heavy Industrial Plants 60 50 40 Hospitals 50 40 30 Commercial Office Buildings 40 30 15 Multi-Residential Complex 25 20 15 Research Laboratories 50 40 30 Table 6.1: MEP Systems as a percentage of Total Building Cost (Tao, 2001) Architectural and structural systems are often designed first with allowances for M E P systems. Tensions between the size of these MEP spaces, usable floor space, and ceiling height exist. As a result, piping, ductwork, and electrical systems must often be fit into very tight spaces and routed in inefficient configurations that are difficult to detail, construct, and maintain. 138 Architect / Engineers typically produce schematic designs of MEP system layouts and routing. It is often up to specialty contractors to finish the design by specifying sizes of ducts and piping, fixtures, and equipment. The design coordination process is performed to allow each trade to compare the materials that are intended for given spaces in a building to ensure they will not conflict physically, or impair the installation and maintenance of subsequent systems. The building contractors perform design coordination with variable levels of effort and results. The timing and necessity of design coordination is highly variable, and the investments and in coordination are dependent on project delivery methods. As discussed in Chapter 2 of this thesis, in building construction the design coordination process is most often performed by comparing or combining shop drawings in a coordination meeting. Systems that cross or overlap are detected by visual inspection, and evaluated for conflicts. If a conflict exists, one or more of the systems must be relocated. New technologies such as 3D and 4D modeling promise to improve design coordination efforts by making design conflicts more visible to designers and construction planners. In isolated cases these technologies have yielded great benefit to users, but are currently perceived to be too costly for widespread use by building contractors. It can be envisioned however, that in the near future, the development of scale digital models of buildings will increase, and that building contractors will find themselves utilizing this technology to complete building design and plan construction operations. There are legitimate questions about how, when, and to what level of detail coordination efforts should be carried out on different types of building projects. As a result, the coordination process is often not performed at an appropriate level of effort during construction planning. The processes and technology used to perform coordination are currently being re-invented by companies that recognize the need for intensive coordination efforts. This transition presents an opportunity to incorporate new concepts such as Lean Thinking (Khanzode et al, 2005) into the traditional construction processes, and hopefully elevate the importance of removing avoidable risks to production systems in building construction. To understand the costs of the MEP coordination and conflicts, one must try to answer the following questions: Coordination effort: How much effort went into ensuring systems could be fit into buildings without physical interference? 139 Field Conflicts: How many field conflicts were found on projects that should have been identified through coordination efforts? Coordination Costs: What were the quantitative costs of the coordination process? Conflict Costs: What were the average costs of field conflicts that were not caught by the design coordination process? In my review on the MEP coordination process of the UBC Chem Bio Project, I have answered the above questions to give an outline on the cost benefits one could have by incorporating 3D modeling technique for the MEP coordination process. Riley and Horman (2001) presented a pre-study of the cost metrics of design coordination, and the relationships between coordination efforts, types of project delivery systems, and field interference problems. 6.2. Coordination Efforts vs. Field Conflicts Figure 6.1 illustrates the relationship found on case study projects studied by Riley and Horman (2001) between the effort spent on coordination and the resulting reduction in field conflicts. Coordination effort was measured by the diligence observed in identifying all potential interference problems prior to allowing construction to proceed in a given area. A rating of 100% indicated that no work was permitted to proceed prior to a coordinated design agreement between all contractors. This rating was reduced on projects when some contractors did not participate, or if some systems or areas of the building were not included. Field conflicts were measured based on the number of field generated change orders pertaining to MEP systems interference. 140 M c o o «*-o a> o z. 30 25 20 15 10 5 0 Project D (28) Project C (9) Project B (2) > Project A (0) 25% 50% 75% Coordination Effort 100% Figure 6.1: Coordination Effort vs. Number of Conflicts (Riley and Horman. 2001) On projects A and B the coordination process was carried out with diligence and treated as a prerequisite for construction. Project A had zero field generated change orders, and project B had only two, both of which occurred due to extreme congestion and re-engineering of systems. On project C a less systematic process was used, and several contractors did not take part in the process. On project D, the general contractor absolved himself from the coordination process, and instructed specialty contractors to perform the coordination process for MEP spaces on their own. It should also be noted that on all four projects, minor conflicts occurred that were settled by negotiation and did not require documented change orders. From the above figure and the nature of coordination that was employed on these 4 projects, we can conclude that the results are less than surprising i.e. the less the coordination effort, the more are the number of conflicts that will occur in the project. The use of field generated change orders was thus found to be a crude but effective method to measure occurrences of conflicts and disruptions. 141 6.3. Conflict Costs vs. Project Delivery Systems Riley in his work (2001) stated that the schedule for coordination meetings is worked backward from the actual construction schedule. Ideally, a three week gap between the coordination meeting signoffs and installation to allow for fabrication adjustments, field layout, and sequence planning is followed. This lead time allows for the results of the coordination process to be full integrated into construction plans, and for the greatest value of the coordination effort to be gained by creating certainty in the dimensional location or embeds, hangers, and sequence of construction. Although it is a critical function of construction managers, very limited research has been performed that fully articulates the value, need, and process by which design coordination is performed for actual building projects. Riley (2000) discussed coordination as a critical part of the construction planning process, and described the benefits of the process and its effects on the field production. The paper identified the role of CAD in the process, the personnel required for the process and their key traits, the timing of the process, the coordination requirements for different facilities, systems to be included in the process, and the variable success of coordination efforts in avoiding field conflicts. It also provided an initial evaluation of how the costs of the coordination process can vary depending on delivery systems, and the range of conflict costs that can be expected on building projects (see figure 6.2). This figure gives useful data on the range of conflict costs that one might incur based on the type of project delivery system and this helps the general contractors and/or owners and/or construction managers to have a fair idea on what will be the possible cost they will incur in the project due to the field conflicts that may arise in the project. As all the projects work on a fixed budget, exceeding the same is not profitable to the person who is bearing most of the cost of the project and hence it is necessary for that participant to have this knowledge so that it can be considered in the bid the team puts in for the project. In addition, as the project progresses keeping a track of the costs incurred due to field conflicts and coordination process, the participant can get an idea of the trend for these costs and have a fair estimate of how much it will exceed or be lower then the initial pre-planned budget for the same. 142 Project Delivery System vs. Conflict Costs Conflict Costs in SK 500 450 400 350 300 250 200 150 100 50 0 <= Q . E c => CD _ , ^Range of total project field-generated change -order costs o 5= _ c o O fc c c n _ j o CL) O ^ CD •£ _ = = c o o U. != C D O CD O 2> CD Delivery System CO Q_ " O £ c n 35 c -o c p -c n ' c o CD CD 2 Q Figure 6.2: Project Delivery System vs. Conflict Costs (fl//ey er. a/, 2007J 6.4. Design Coordination Costs vs. Project Delivery Systems Riley and Horman in their study (2001) used the historical cost data from the same 14 projects they had used to deduce Figure 6.2, in an effort to identify the range of costs associated with performing design coordination. Costs were measured in terms of hours required for the MEP project manager (general contractor) and for CAD operators, foremen, and project managers (specialty subcontractors). Variable types of delivery systems and coordination methods were used on these projects. Figure 6.3 illustrates the ranges of coordination costs found on projects with similar delivery systems. The cost increase of the earlier involvement in negotiated delivery methods was found to be significant but less dramatic than the costs of field conflicts show in Figure 6.2. 143 Figure 6.3: Type of Delivery System vs. Coordination Costs (Riley, 2001) A conservative comparison of coordination costs (Figure 6.3) and typical conflicts costs (Figure 6.2) for different types of delivery systems demonstrates that coordination efforts on MEP intensive projects typically pay for themselves in real costs. This is encouraging, as contractors struggle to justify preconstruction expenses and planning costs in negotiated contracts. Thus, based on the data presented above, we can conclude that investments in coordination typically pay for themselves by reducing conflicts and field generated change order costs in MEP intensive projects. The limited data used in the research above was not sufficient to develop predictive models of coordination costs and resulting savings in field conflicts costs. A more robust study was needed to characterize the time and cost metrics of coordination investments based on project type, system design, project intensity, and density of MEP systems and the study and the predictive models formulated by Riley et al. in their study (2005) is discussed in the next section. 144 6.5. Factors Governing MEP Coordination Costs in a Project Riley et al. in their study (2005) identified the various factors that affect the coordination efforts and costs in a project by conducting a survey among the project managers in 12 projects of varying utility such as research labs, pharmaceutical labs and hospitals with the total cost of project ranging from $5.5 million to $228 million. This range of data enabled them to understand the intrinsic details on the factors that affected coordination costs. These factors are listed below: • Type (usage of project): Indicates the types and relative density of mechanical systems • Project delivery system (CM/GC versus design-build): Affect the timing and responsibility of coordination • Contract type (lump sum versus GMP) • Density of building (construction cost/gross SF): Reflect the relative volume of MEP work on the project compared to other projects • MEP density (MEP contract costs/gross SF) • Intensity of MEP systems (MEP contract costs/SF/month): Affects the rate at which construction will need to take place, and the time available to resolve conflicts • Average floor-to-floor height, "FF" (feet): Reflect the relative space available to fit MEP system in and around structural and architectural building elements • Plenum height (FF height less floor height and structural system depth) • Structure type (steel versus concrete) • Timing of coordination (early or typical): Reflects the ability of coordination problems to be detected and solved before they are found in the field. The survey asked the project managers to rank these factors and of these, MEP density and plenum height were concluded to be the major factors that affect the coordination effort and coordination costs. Based on this conclusion and the data collected in the 12 projects and the regression analysis results, Riley et al. (2005) developed a linear and polynomial Model for the computation of coordination costs with respect to these two factors. • Linear Model: CCost = 2.0380 + 0.0081(MEPD) - 0.4067(PH) • Polynomial Model: CCost = 3.2627 + 0.0184(MEPD) - 0.00008(MEPD)2 - 1.2676(PH) + 0.1213(PH)2 145 Where CCost = coordination cost per square foot; MEPD = MEP density in $/SF; and PH = Plenum height in feet. The accuracy of these models was checked by doing the back calculation of the actual MEP coordination cost for the 12 projects and it was concluded that the percentage error of the coordination cost resulting from the polynomial model was minimal in comparison to the linear model and hence this can be useful for the general contractors to estimate the possible coordination cost they might incur in the project and can thus account for that in their bid. However, it is important to note that the predictive models are based only on the two variables that demonstrated the strongest relationship to coordination costs. Many variables, such as the timing of coordination, project size, and project complexity, are not included in the model. It is also important to note that the coordination cost data used came from a single contractor, and that other methods of accounting for coordination cost may yield different results. This gave me an excellent opportunity to determine the effect on coordination costs from the factors that were outlined by Riley et al. (2005) on the UBC Chem Bio Project which shall be discussed in the following section and verify whether the general contractor / construction manager was on budget with these costs. This verification was also important as this project made use of 3D modeling technique for MEP coordination. My evaluation of this project shall yield 2 main results with respect to this project; • How expensive was it to do 3D modeling for MEP coordination with respect to the predicted MEP coordination costs from Riley's models and, • How much cost savings were resulted by implementing 3D modeling technique in the project. 6.6. Types of Field Conflicts vs. Productivity and Costs due to Field Conflicts Riley and Horman in their work (2001) stated that to streamline flow in construction, trades must complete work in a logical sequence with minimal interruptions to flow. When conflicts are discovered in the field, it is usually too late to avoid some form of interruption and delay while the conflict is resolved. When a crew is forced to stop work and relocate, wait for information or 146 for materials, productivity will be adversely affected. Subsequent crews of following activities are often affected in the same way, compounding the problem. The costs of these conflicts and the extent to which other crews are affected will vary depending on project complexity (Riley, 2000). Effective production management strives to maximize conversion processes, or actual construction work, align flow processes between subsequent activities in a sequence, and minimize non-value added activities such as the movement between work areas and material handling (Womak, 1996). Extensive research has been conducted on the coordination of specialty contractors and issues surrounding contract management. Tommelein (1998) provides a comprehensive review of this literature. Discussion of the design coordination of however, has been limited to computer modeling, either through frameworks for design collaboration or through 3D modeling of components and automatic interference detection (Neggers and Mulert, 1993). Tommelein (1998) created perhaps the most thorough map of the issues surrounding the coordination of specialty contractors. She specifically highlighted the role of the general contractor in clarifying contract documents and acquiring as-built drawings for work done by others on which specialty contractors must build. She notes that unless exact field dimensions are obtained, it may be impossible for the specialty contractor to complete design details, thereby delaying procurement, fabrication, and field installation. Pressures to reduce field staff and general conditions costs conflict with needs to invest in extensive coordination efforts. While it is understood that coordination efforts can reduce overall project costs by minimizing field conflicts, little data is available to demonstrate the value of coordination in real dollars. (Riley, 2001) Riley et al. (2005) did a more detailed study on the types of conflicts that affected the productivity of the MEP coordination process by conducting a survey among the foremen in which they asked the foreman to provide information on specific effects of field conflicts. The result of the survey is as shown in Figure 6.4. 147 Overmanning Schedule Overtime Space Conflicts Future Material Loss of Compression Storages Productivity Figure 6.4: Effects of Field Conflicts (Riley et al., 2005) The above figure shows that the loss in productivity is highest in case of Type 3 Conflicts. The most common effect of Type 1 conflicts was schedule compression, which resulted from 79 percent of the Type 1 conflicts. Space conflicts, loss of management, extra coordination, and under manning were much less frequent, with each affecting less than 30% of Type 1 conflicts. Occurrence of each effect was more frequent for Type 2 conflicts than for Type 1 conflicts, with the exception of schedule compression. Space conflicts, loss of productivity, and schedule compression were the most common, resulting from 84%, 74%, and 53% of Type 2 conflicts, respectively. Additional effects of Type 2 conflicts listed by foremen but not included in Figure 5.3 include loss of preplanning hours, extra material costs, and added supervision. Type 3 conflicts had the maximum impact, with every Type 3 conflict resulting in loss of productivity, and over one-half resulting in schedule compression (74%), space conflicts (63%), and overtime (63%). Other effects included lower crew morale and added supervision. In summary, the later a conflict arose, the more frequently negative effects were observed. This graph gives us a significant picture on what effect the various field conflicts have on the factors that affect the productivity in the project. Overall we can deduce that the loss in productivity is minimal in case of Type 1 conflicts and hence the contractors should focus more on achieving an early coordination of MEP systems to have minimal loss in productivity and this 148 in turn also reduces the cost overheads that the sub trades might sustain if the delay their work. This was illustrated by Riley et al. (2005) in the survey they conducted among the project managers and mechanical contractors to determine an average cost resulting from these three types of conflicts. The findings are as shown in Figure 6.5. Cost of Field Conflicts vs. Types of Conflicts Resulting Cost in $ Type 1 Type 2 Type 3 Types of Conflicts Figure 6.5: Type of Field Conflict vs. Resulting Cost (Change Order) (Riley et al., 2005) It was noted that, on average, for every five field conflicts, only one resulted in cost recovery via a change order—in other words, costs of approximately 80% of the field conflicts are not recovered by contractors. In the UBC Chem Bio Project, all the conflicts that have been identified by Tabesh and Staub-French (2005), were prior to the start of construction at the site and, based on Riley's Classification (see Table 6.2), these conflicts are Type 1 and hence the most concurrent effect of the conflicts should be observed on schedule compression and there should be a minimal loss in productivity. However, based on my analysis of the UBC Chem Bio Project in NavisWorks discussed in Chapter 5, I have observed that there have been several conflicts that were left undetected by Tabesh and Staub-French (2005) in their study on the project which may have been detected at the site, thus being Type 3 field conflicts. Hence to say that there would have been no major loss in productivity on the UBC Chem Bio Project would be an understatement, but how much detrimental effect these field conflicts would have had on the on-site productivity 149 is something that would remained unanswered as there has been no documentation on the field conflicts that were observed on the project whilst construction of the building. Sr. No. Type of Coordination Conflict Description Severity of Impact 1 Type 1 Detected and resolved before installation has begun. Start of work is potentially delayed, redesign is required. 2 Type 2 Detected after Trade 1 has completed work, Trade 2 forced to reroute work. Trade 2: Disrupted and potential redesign and fabrication changes are required. 3 Type 3 Detected after Trade 1 has completed work, Trade 2 forced to wait until Trade 1 moves work. Trade 1: Disrupted, rework, and redesign required. Trade 2: Delayed. Table 6.2: Types of Coordination Conflicts, Timing of Detection, and Severity of Impact Also, Tabesh and Staub-French (2005) had estimated a possible 975 number of interferences/conflicts for the project if the entire MEP Coordination was done prior to the commencement of the construction on-site i.e. all the interferences they estimated could be classified under Type 1 for the UBC Chem Bio Project. The cost benefits resulting from doing a detailed 3D MEP coordination process can be made under the conditions; • What would be the resulting cost of conflicts if there was no MEP coordination done on the project at all i.e. determining all the interferences/conflicts at the site or all the conflicts would be of the Type 3 and, • What would be the resulting cost of conflicts if the entire MEP coordination was done prior to the commencement of the. work on-site or all the conflicts would be of the Type 1? The difference between the above two costs will be the cost benefits one would have from the 3D MEP coordination process done on the project. Under the current studies by Tabesh and Staub-French (2005) and Riley et al. (2005), for the UBC Chem Bio Project; the cost of field conflicts if all the conflicts are of Type 3 will be: Type 3 Field Conflict Costs = 975 * average (30,000 and 3,000) = $ 16 Million and, the cost of all the conflicts if they are of Type 2 will be: Type 1 Field Conflict Costs = 975 * average (0 and 1000) = $ 0.49 Million 150 Therefore the approximate value for the resulting cost savings will be: Cost Savings = ($16 - $0.49) Mil l ion = $15.51 Mil l ion On the lines of the above calculations, for the interferences Tabesh and Staub-French (2005) already identified in their study (50 number of interferences), this cost savings they have already attained for the project is $0.8 Million which itself is a big amount of saving for a project on a tight schedule and fixed budget. The above analysis thus proves that having an early but right type of coordination on a project is always beneficial and 3D modeling just adds to this value of MEP coordination. However, it is also important to understand how much 3D modeling technique affects the MEP coordination cost, which will be discussed in more detail for the UBC Chem Bio Project in the following section. 6.7. M E P Coordination Cost for U B C Chem Bio Project 6.7.1. Computation of Actual M E P Coordination Cost Riley et al. (2005) gave a comprehensive list of attributes i.e. project participant, cost per hour of the project participant, working hours per week for the project participant, working duration per week of the project participant that needs to be collected for computing the actual coordination cost in a project (See Table 6.3). I submitted the entire set of attributes with the various project participants involved in the MEP coordination for UBC Chem Bio Project to my supervisor who forwarded the same to the Project Manager. The underlying theory for this entire calculation of the actual coordination cost is the actual coordination cost for any project is the cost of the time spent by each project participant whilst the entire duration of the project on the coordination process. In the case of the MEP coordination process, the time spent by the following project participants governs the actual coordination cost: • Design Consultants: Architectural, Structural, Mechanical, Electrical, Plumbing, Fire Protection • General Contractor I Construction Manager: Project Manager I Engineer, MEP Coordinator, Field Superintendents • Specialty Contractors: HVAC Piping (Detailers, Engineers and Foremen), HVAC Ductwork, Electrical, Plumbing, Fire Protection 151 The salary of these project personnel on a per hour basis was used to compute the total cost for these project personnel for the 3D MEP Coordination Process. This Total cost has been further multiplied with a location factor (determined from RSMeans for the city, in this case Vancouver) and the inflation index of the country to get the Actual Coordination Cost for the entire project. As I could not get the exact figures for the salaries of the project personnel involved in this project, I have assumed the following for the salaries of the project personnel: • All Design Consultants: Annual Salary = $125,000 i.e. $60/hour for 40 working hours per week. • General Contractor / Construction Manager: o Project Manager / Engineer: Annual Salary = $90,000 i.e. $45/hour for 40 working hours per week. oMEP Coordinator: Annual Salary = $80,000 i.e. $40/hour for 40 working hours per ' week. o Field Superintendents: Annual Salary = $70,000 i.e. $35/hour for 40 working hours per week. • Specialty Contractors: o HVACPiping-• Detailers: Annual Salary = $60,000 i.e. $30/hour for 40 working hours per week. • Engineers: Annual Salary = $60,000 i.e. $30/hour for 40 working hours per week. • Foremen: Annual Salary = $70,000 i.e. $35/hour for 40 working hours per week. o For the HVAC Ductwork, Electrical, Plumbing, Fire Protection Contractors, the team is the same as the HVAC Piping Contractors i.e. Detailers, Engineers and Foremen, so I have assumed that they too will have the same cost as that incurred by the HVAC Piping Contractor. • In the UBC Chem Bio Project, the project participants incurred an additional expense in the form of the student from UBC who created the 3D Models for MEP coordination Process and his salary was $20/hour. 152 All the above costs are in Canadian Dollars and the detailed computation of the Actual Total Coordination for the 7200SF of building area wherein 3D modeling was used for MEP coordination is shown in Table 6.3. Project Participant Cost per hour in $ No. of Personnel Working Hours per week Working Duration in weeks Total Cost of the Personnel in $ (a) (h) .(c)- (d) (e)= (a)*(b)*(c)*(d) Design Consultants5 Architectural 60 1 2.5 10 $1500 Structural 60 0 0 10 0 Mechanical 60 2 . 2.5 10 $3000 Electrical 60 1 2.5 10 $1500 Plumbing 60 1 2.5 10 $1500 Fire Protection 60 0 0 10 $0 Sub-Total of Costs for Design Consultants $7500 General Contractor / Construction Manager Project Manager / Engineer 45 1 1.25 10 $562.50 M E P Coordinator of G C / C M 40 1 1.25 10 $500 Field Superintendents • 35 1 1.25 10 $437.50 Sub-Total for Costs for General Contractor/Construction Manager $1500 Specialty Contractors H V A C Piping: Detailers 30 0 0 10 $0 Engineers 30 • 1 1.25 10 $375 Foremen 35 1 0.75 10 $262.5 H V A C Piping Cost $637.50 H V A C Ductwork Cost $637.50 Electrical Cost $637.50 Plumbing Cost $637.50 Fire Protection Cost $637.50 Others (3D Modeler: Student from UBC) 20 1 37.5 8 $6000 Owner's Cost $0 Sub-Total for Costs for Specialty. Contractors $9187.50 Sub-Total of all the costs $18187.50 Location Factor (@7% higher) $1273.13 Inflation Index (@1.9% higher) $345.57 Total Actual Coordination Cost after adjustment $19806.20 Table 6.3: Computation of Actual Coordination Cost for UBC Chem Bio Project 153 The Total Actual Coordination Cost computed in Table 6.3 i.e. $19,806.20, is for an area of 7,200SF of the Building wherein the owner had made use of 3D Modeling Technique for MEP Coordination Process and all the values are in Canadian Dollars. Under the assumption that the same intensity of coordination cost will be incurred if the MEP coordination process for the entire building area (123,000SF) is done using 3D Modeling Technique then, the Total Actual MEP Coordination Cost for the entire project is: Total Actual MEP Coordination Cost (ACCost) = (19806.20/7200)*123000 = $ 338,356 The above value of $338,356 signifies that if the predicted model gives us a value less then this value then the project is under budget else the project is over budget by the difference. The computation of the Predicted Coordination Costs for the UBC Chem Bio Project is discussed in the next section. 6.7.2. Computation of Predicted Coordination Costs From the 2D Architectural Drawings of the project, I could gather the information on the plenum height (3.45 ft.) and Average Floor to Floor Height (12 ft.). Tabesh and Staub-French (2005) had highlighted the total project cost ($38 Million), project duration (13 months or 52 weeks) and project area (123,000 SF) and the owner gave me an estimate of $10 Million as the MEP Contract Price for the entire project of which 10% was estimated for the 2 small buildings adjoining the main 6 Storey Structure. This basic data from the owner helped me estimate the Coordination Cost for the project from the Linear and Polynomial Models (Riley et al., 2005). The detailed computation of the costs for the predicted models by Riley et al. (2005) and its variance with respect to the actual coordination cost for the UBC Chem Bio Project is shown in table 6.4. 154 Name Units Abbreviation Equation for Calculation Value in units Remark Total Construction Cost of the Project $ TConCost $38,000,000 These values have been recorded from the project files such as drawings and contracts M E P Contract Cost of the Project $ MEPCost $10,000,000 Total Area of Building/Project SF B A 123,000SF Project Duration weeks PD 52 weeks Plenum Height Ft. PH 3.45 ft. Average Floor to Floor Height Ft. FF 12 ft. Total Actual Cost of M E P Coordination $ ACCost $338,356 Computed in Section 6.7.1 Building Density $/SF BD BD = TConCost / B A 308.94 $/SF M E P Density $/SF MEPD MEPD = MEPCost / B A 81.30 $/SF M E P Intensity $/SF/week MEPI MEPI = MEPD / PD 1.56 $/SF/week M E P Costs as percentage of Total Project Costs % M E P % M E P % = MEPCost / TConCost Predicted Coordination Cost derived from Riley's Linear Model $/SF LCCost LCCost = 2.0380+ 0.0081 (MEPD) - 0.4067 (PH) 1.29 $/SF Total Predicted Coordination Cost derived from Riley's Linear Model $ TLCCost TLCCost = LCCost * B A $158,670 Predicted Coordination Cost derived from Riley's Polynomial Model $/SF PCCost PCCost = 3.2627+ 0.0184 (MEPD) - 0.0008 (MEPD) 2 -1.2676 (PH) +0.1213 (PH)2 1.30 $/SF Total Predicted Coordination Cost derived from Riley's Polynomial Model $ TPCCost TPCCost = PCCost * B A $159,900 Variance of Total Actual Coordination Cost with respect to Total Predicted Linear Model Coordination Cost , $ VL VL = ACCost - TLCCost $179,686 Variance of Total Actual Coordination Cost with respect to Total Predicted Polynomial Model Coordination Cost $ . . VP VP = ACCost - TPCCost $178,456 Table 6.4: Computation of Predicted MEP Coordination Costs for UBC Chem Bio Project 155 From the above table, we can conclude that the Total Actual MEP Coordination Cost for the entire UBC Chem Bio Project thus exceeds the predicted values by $178,456 i.e. based on the predicted polynomial model (which gives the most accurate value for the MEP Coordination Costs, Riley et al. (2005)) and we can say that the general contractor is over budget by approximately $178,500. 6.8. Conclusion In Summary, the predictive model designed by Riley et al. (2005) gives us an estimate of the coordination costs that one might incur in the project and this can be accounted for in the bid. Also, if the general contractor / owner keep track of the time used for doing the MEP coordination then one can compute the variance of the actual coordination cost with respect to these predictive models at every stage of the project to understand how much cost has been incurred to date on doing the coordination process and what is the balance that can be spent on the same so that the project remains on budget and having a 3D modeling technique with the right kind of system and modeler is always beneficial for a project of high MEP intensity. For the UBC Chem Bio Project, if the general contractor was to make use of 3D modeling technique for the whole project, the resulting cost he would have incurred will be $338,356 or $0.34 Million, which is a large amount of investment in a lump-sum contract project but the cost benefits of using a 3D modeling technique for MEP coordination he will extract in dollar value will be approximately $15.51 Million which excludes the time and productivity losses he will minimize on the project. To conclude, the investment on the right of MEP coordination process (in this case use of 3D MEP coordination process) is always beneficial in terms of cost, time and productivity so an investment of $0.34 Million is meager and worth every penny invested. The summary of study of MEP coordination costs for UBC Chem Bio Project is shown in Table 6.5. 156 Project Characteristic ' .'' • UBC Chem Bio Project • J J g v Building Usage Research Lab and Classrooms Project Delivery System CM/GC Contract Type Lump-sum Total Construction Cost ($) $ 38,000,000 MEP Contract Cost ($) $ 10,000,000 Building Area (SF) 123000 SF Project Duration (weeks) 52 weeks Building Density ($/SF) 308.94 $/SF MEP Density ($/SF) 81.3 $/SF MEP Intensity ($/SF/week) 1.56 $/SF/week MEP Costs as % of Building Costs 26.32% Average Floor to Floor Height (feet) 12 ft. Plenum Height (feet) 3.45 ft. Timing of Coordination Early Level of Coordination High Actual Total Coordination Cost ($) $ 338,356 Predictive Coordination Cost: Linear Model Coordination Cost ($/SF) 1.29 Total Coordination Cost from Linear Model ($) $ 158,670 Polynomial Model Coordination Cost ($/SF) 1.3 Total Coordination Cost from Polynomial Model ($) $ 159,900 Variance: Variance from linear model ($) $ 179,686 Variance from polynomial model ($) $ 178,456 Table 6.5: Summary of MEP Coordination Costs for UBC Chem Bio Project 157 Chapter 7: Conclusions and Recommendations for Future Work Areas 7.1. Conclusions There is wide variation in the level of technology used in the MEP coordination process. At the low-tech end of the spectrum, specialty contractors draft plan-views on translucent media and prepare section-views when necessary. At the other extreme, progressive contractors have used 3D CAD to improve the process. The use of 3D modeling and collaboration of the MEP systems overcomes the limitations of the conventional paper-based 2D MEP coordination procedure. In 2D MEP coordination process, the project participants sit down to check for conflicts only after they finish the first draft of the 2D Drawings and this delays the entire coordination process by using of 3D modeling technique for the MEP coordination, the designers can do a development-time conflict resolution, thus reducing the total time for MEP coordination process. Constraint-based design uses constraints to describe a design, and uses computational methods to search for a feasible and/or optimal solution/design and governs a large part of the MEP coordination process and the modeler should check the MEP systems designed for the project for conflicts generated by the various governing constraints. NavisWorks is more capable to handle clearance related constraints and to check for conflicts generated from the remaining constraints (component property related constraints, position related constraints, access related constraints, component installation sequence related constraints, space related constraints), we need a more sophisticated tool than NavisWorks. However, in comparison to ABS, NavisWorks is definitely better as a constraint based conflict detection and management tool. In this thesis, after simulating the 3D models of UBC Chem Bio Project for 7 clearance related constraints and one physical interference test in NavisWorks, which resulted in a total of 147 active conflicts which were left undetected by Tabesh and Staub-French by using ABS. Thus, I can conclude that NavisWorks is better conflict detection and management tool than ABS. For the UBC Chem Bio Project, if the General Contractor was to make use of 3D Modeling Technique for the whole project the cost benefits it yields is approximately $15.51 Million which excludes the time and productivity losses he will minimize on the project. Thus, based on the data presented above, we can conclude that investments on the right kind of MEP Coordination Process (in this case use of 3D Modeling Technique) at the right time (early) and 158 with right level of coordination effort (high) by the project participants is beneficial in terms of cost, time and productivity and typically pay for themselves by reducing conflicts and field generated change order costs in MEP intensive projects. 7.2. Recommendations for Future Work Areas In NavisWorks, I was able to simulate only 7 from 26 design and modeling constraints listed in Table 5.2 which indicates the lack of information and inability of the tool in study, NavisWorks to model all the constraints governing the MEP systems for conflicts. This is one of the areas where we need more research. Also, while checking for clearance-based constraints on the model, NavisWorks does not have the ability to check for specific sides of the component, so we need a tool that will help us in doing the same as manual review of the conflicts in the entire zone of clearance for complex MEP systems will be a tedious job. Few of the constraints governing MEP systems, are installation sequence-based and NavisWorks does not have the ability to check for time-based conflicts and hence we need a more sophisticated tool than NavisWorks which can act as a comprehensive conflict detection and management tool for the industry. Although, NavisWorks acts as a good conflict management tool as it has the ability to generate reports of the clash tests that one runs on the project, there is a need to develop a knowledge capture tool which will capture the ideas discussed in the MEP coordination meetings or a meeting tracker to work in conjunction with the conflict detection and management software. 159 References A. Reza Tabesh and Sheryl Staub-French. (2005). "Case Study of Constructability Reasoning in MEP Coordination." Proceedings: Construction Research Congress 2005: Broadening Perspectives. San Diego, California, U.S.A. A.C. Harfmann and S.S. Chen (1993). "Component-based building representation for design and construction." Automation in Construction, 1(1993) 339- 350. Anna .C. Thornton (1996). "The Use of Constraint-based Design Knowledge to Improve the Search for Feasible Designs." 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"Building assembly detailing using constraint-based modeling" Automation in Construction 12 (2003) 365- 379; Korman, T and Tatum, R. (1999) "Improving the MEP Coordination in Building and Industrial Projects." CIFE Research Report, Stanford University, Stanford, CA Korman, T. M. (2001). "Integrating multiple products over their life cycle: An investigation of mechanical, electrical, and plumbing coordination.''' PhD thesis, Stanford University, Stanford, California, U.S.A. Korman, T.M., and Tatum, C.B., (2001). "Development of a Knowledge-Based System to Improve Mechanical, Electrical, and Plumbing Coordination." Technical Report No. 129, CIFE Research Report, Stanford University, Stanford, CA. Korman, T.M., Fischer, M., and Tatum, C.B., (2003). "Knowledge and Reasoning for MEP Coordination." J. Construction Engineering and Management, ASCE, New York, NY, 129(6) 627-634. M. Kilkelly (2000). "Off the page: object oriented construction drawings." ACADIA 2000, October. 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Proceedings: 9th Annual Conference of the International Group for Lean Construction (IGLC-9), 129-136. 161 Riley, D.R. (2000). "Coordination and Production Planning for Mechanical, Electrical and Plumbing Construction.'''' Proceedings: ASCE Construction Congress VI, Orlando, FL. Sohrt, Wolfgang and Bruderlin, Beat (1991). "Interaction with constraints in 3D modeling.'" Proceedings: Symposium on Solid Modeling Foundations and CAD/CAM Applications, 1991, p 387-396. Tao, William K. Y., and Janis, Richard R. (2001). "Mechanical and Electrical Systems in Buildings.'" Prentice Hall, Columbus, 2001. Tatum, C. B., and Korman, T. M. (2000). "Coordinating building systems: Process and knowledge:' J. Architectural Engineering, ASCE, NY, 6(4), 116-121 December (2000). Tommelein, LD. and Ballard, G. (1998). "Coordinating Specialists." Journalof Construction Engineering and Management, ASCE, New York, NY, 126 (2) 56- 64, January. W. Hower and H. Graf (1996). "A bibliographical survey of constraint-based approaches to CAD, graphics, layout, visualization, and related topics." Knowledge-Based Systems, 9 (1996)449-464. Womak, J.P. and Jones, D.T. (1996). "Lean Thinking: Banish Waste and Create Wealth in your Corporation." Simon and Schuster, New York, NY, 350pp. 162 

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