International Construction Specialty Conference of the Canadian Society for Civil Engineering (ICSC) (5th : 2015)

Comparitive study of current practice in bridge condition assessment Ahmed, Marwa H.; Bhowmick, Anjan; Moselhi, Osama Jun 30, 2015

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5th International/11th Construction Specialty Conference 5e International/11e Conférence spécialisée sur la construction    Vancouver, British Columbia June 8 to June 10, 2015 / 8 juin au 10 juin 2015   COMPARITIVE STUDY OF CURRENT PRACTICE IN BRIDGE CONDITION ASSESSMENT Marwa H. Ahmed1,2,  Anjan. Bhowmick1 and Osama. Moselhi1 1 Building, Civil, and Environmental Engineering Dept., Concordia University, Canada. 2 mar_ahme@encs.concordia.ca Abstract: Bridges play a vital role in road infrastructure networks. According to Statistics Canada, bridges and overpasses accounted for 8% of total public assets in 2007.. Ontario ranked as the third among provinces in terms of having old bridges. In 2007, Bridges in Ontario accounted for 7% of its public infrastructure, while in Alberta, bridges account for 9% of total public infrastructure. Bridge condition assessment is conducted to determine load rating capacity for bridge elements. The identification of current condition of each element provides early warning of necessary maintenance. Condition rating is performed during the inspection process. This paper provides a comparative study of current practices in bridge condition rating worldwide, with emphasis on the United States and Canada. The study includes 4 main criteria: inspection levels, inspection principles, inspection frequencies and numerical ratings for 4 provinces in North America: Alberta, Ontario, Quebec and state of Oregon and 5 countries outside North America: United Kingdom, Denmark, Portugal, Sweden and Australia. The Limitations of current practices are discussed and recommendations for improved inspection are provided. The study is expected to assist professionals and inspectors in selecting feasible method/s for effective bridge condition assessment.  1 INTRODUCTION Bridge Management System (BMS) is the process of monitoring, inspection, repair and replacement of deteriorated bridges. All bridge management decisions require inspection data to identify current condition of bridges. Moreover, it provides decision making with tools to select the appropriate solution, such as bridge rehabilitation or replacement. BMS is facing imbalance between the need for repairs or replacements and many challenges due to incorporating of multi objectives; structural safety, serviceability, optimum maintenance and economic considerations. Therefore, BMS cannot make decisions without accurate and detailed data of bridge conditions. Thus, decision makers can avoid the worst consequences of underestimating the degree of deterioration and avoid the costly consequences of overestimating the degree of deterioration. The main goal of BMS is to gain the maximum performance with using minimum cost and this can be achieved by efficient techniques and technologies that can be automatically updated. Consequently, the service life of bridges can be increased within effective cost. (Rens et al. 2005; Steart et al. 2002, Wang et al.2007). Structural health monitoring, inspection process and condition assessment are considered main components of BMS.  Bridge condition assessment is conducted to determine load rating capacity for bridge components. The main components of bridges are deck, superstructure and substructure. Each component has different role in bridge structure with specified relative importance. Bridge condition assessment defines the 220-1 structural importance of each bridge element. The identification of current condition of each element provides with early warning of necessary maintenance. The main difficulty in bridge condition assessment is the large number of bridges in the network which requires regular inspection. However, condition rating is performed using the inspection data. These collected data are converted to a rating to assess bridge condition (Xia and Brownjohn, 2004; Yehia et al. 2007). This paper presents a detailed comparison of current practices of condition assessment of bridge structures in different countries.  2 CURRENT PRACTICE IN BRIDGE CONDITION ASSESSMENT  IN NORTH AMERICA According to Federal Bridge Inspection Standard (FBIS), the levels of service deficiencies are based on comparisons of the actual load capacity of bridge with the level of service. The evaluation of bridge condition deficiency (BCD) includes an assessment of the condition of each of the three primary elements of the bridge: Super structure (SPD), Substructure (SBD) and bridge deck (BDD). After the total deficiency has been established for all bridges, costs associated with replacement and rehabilitation should be determined (FHWA, 2012; Branco and de Brito, 2004).  BCD= SPD+ SBD+ BDD……………………………………………………………………Eq.1  Condition ratings for each element of the bridge are assigned every two years and are then aggregated into overall condition ratings for super, sub structure and deck, the ratings are numerical values from 0 to 9. Bridges are considered structurally deficient if any of deck, substructure or superstructure is equal or less than 4 (poor). If the structural evaluation is equal or less than 2, then the bridge is having high priority for replacement ( FHWA, 2012; Branco and de Brito, 2004). According to the manual for maintenance inspection, AASHTO describes two basic load rating procedures: (1) the allowable stress, (2) Load rating, LR. In the United States, bridges are periodically rated according to their structural capacity. The rating can actually increase with time in bridges inspected regularly with maintenance programs, where the live load limits are checked by traffic police 2.1 Bridge Condition Assessment In Alberta Transportation According to Bridge Inspection Manual of Alberta Transportation, the condition rating system in Alberta consists of a numerical rating range of 1 to 9 (BIM 2004;  Branco and de Brito 2004). This rating applies to all inspection elements as well as the general rating for each category. The rating is representative of the condition of the element and the ability of the element to function as originally designed. Bridge can be rated 9 if it is in excellent condition. Additionally, the rating of the element also reflects any safety concerns and maintenance priority. The rating of an element is determined by the rating of the worst item within the group. The inspector should describe, and explain the condition, why the post has a low rating and where it is located.   The rating of the element is visual inspection and based on what the inspector can see. The inspector should be able to see enough of the element to be comfortable assigning a rating. If the element is inaccessible or is not visible for the inspector to assign a rating, the element is rated ‘N’. If a particular element does not apply to the structure being inspected, the element is rated ‘X’. In situations where an element does not exist but is required in the judgment of the inspector, the element is rated ‘X’ with a comment provided in the ‘Explanation of Condition’ section which illustrates within a maintenance recommendation (BIM 2004 ). The general rating for each category is determined by the ratings assigned to critical load carrying elements or members of the structure. The general rating must also reflect any safety concerns related to the function of the structure. The general rating is not an average of the element ratings; as the general rating cannot be higher than the lowest critical element rating.  All bridges are to be inspected in accordance with the following intervals to ensure an appropriate level of safety: major bridges, Standard bridges, in highways with numbers less than 500 or greater than or equal to 900 are within 21 months interval. Major bridges, standard bridges in highways with numbers equal to or greater than 500 but less than 900 are within 39 months interval. Major bridges in parks that carry pedestrian traffic only are inspected within 57 months interval. All new bridge structures are to be inspected immediately after construction is complete and within 24 months after completion. All bridge 220-2 structures are to be inspected immediately after any significant maintenance or rehabilitation is completed. The inspector may specify shorter intervals depending on the age, traffic characteristics and known deficiencies (BIM 2004;  Branco and de Brito, 2004).  Most major bridges, standard bridges, are inspected by a certified bridge inspector on a routine basis which is known as Level 1 inspection. However, certain major bridges or components of standard bridges require inspection with specialized knowledge, tools and equipment. Almost all bridges will require specialized inspections which are known as Level 2 inspections. Specialized inspection includes ultrasonic tests on steel bridges, CSE tests on deck concrete, coring test. Level 2 inspections are essential for high load and overload damage, or where critical or significant deficiencies are determined (BIM 2004;  Branco and de Brito, 2004) . Level 1 is a general inspection which requires completion of the BIM report and use of basic tools and equipment. This level of inspection must be undertaken by certified bridge inspectors. Level 1 inspections are general visual inspections conducted using standard tools and equipment. This level must be performed at time intervals not exceeding those specified by Department policy. Level 1 inspection rate the worst part of each element and do not take the overall element condition into account.  Level 2 inspection is an in-depth inspection which requires completion of the BIM report, and use of specialized tools, techniques, and equipment. Level 2 inspections are quantitative inspections conducted using specialized tools. This level of inspection gathers detailed information on the condition of a particular bridge. In Alberta, concrete deck inspections are currently performed on approximately 120 bridge sites per year throughout Alberta on a 4 to 5 year inspection cycle. Additional Level 2 deck inspections may be completed as part of a bridge assessment that identified in a previous Level 1 inspection. The quantified condition data that are collected provide information on the element and this condition can be monitored over time. The condition rating for Level 2 inspections are grouped together into categories. Therefore ratings from 9-7 are grouped as very good condition ratings, and then ratings 6 and 5 are grouped as adequate ratings. Ratings of 4 and 3 are grouped as ratings that are the most critical and give priority of the element. Ratings of 2 and 1 are grouped as these ratings are required immediate maintenance or repair. The inspector should rate the general condition and not just the worst case. The inspector should note that if the damage is significant to the structural capacity.   Level 1 rating should be used to reflect the worst damage to the element. A rating of 5 or higher is for elements that are functioning as designed. For a rating of 5 an element may have minor structural flaws, but these flaws should not impact the structural capacity of the member. A rating of 4 is a low maintenance priority, and these elements would generally be scheduled for repair in more than 3 years. A rating of 3 is a medium priority for maintenance, as repairs would typically be scheduled from 6 months to 3 years away. A rating of 2 is a high priority for maintenance and repairs would likely be less than 6 months away. A rating of 1 requires urgent and immediate action.  The Chloride Test is a field test to determine the chloride content of concrete.  It is most often performed on a deck because these are the areas of the bridge that are commonly exposed to the de-icing salt. This test is performed in level 2 inspection. Chloride testing is destructive because holes are drilled into the component that is being tested. This testing is also time-consuming as the samples must be extracted and tested. The destructive and time-consuming nature of the test means that only a limited number of samples can be gathered and tested. Copper Sulfate Electrode (CSE) test is a repeatable, non-destructive field test. Alberta Transportation remains one of the few agencies that use CSE testing as a predictive tool for preventative maintenance programs. CSE testing, also referred to as half-cell testing is used to determine the potential of corrosion in reinforcing steel, but they do not indicate a corrosion rate. Test results from one year to another are compared to assess the advancement of corrosion and predict the future deck condition. The CSE data are used to develop prediction models and to determine the ideal time to rehabilitate a deck. CSE data is also used to evaluate the effectiveness of various rehabilitation methods. CSE testing is quick, and cost-effective. The limitation of CSE testing is that, suddenly the readings become higher, lower, as the ground connection may be broken, the voltmeter connections may have worked loose, or the grounding wire may be broken. In this case, inspector should stop and verify the validity of the ground connection or check if the deck is not wet enough for accurate results. 220-3 2.2 Bridge Condition Assessment in State of Oregon, USA The Oregon department of transportation (ODOT) considers the routine inspection report to be the primary tool for reporting the condition of a structure. The routine inspection report is a summary of condition assessment data that is generated via a number of more detailed types of inspections. A Routine Bridge Inspection is a regularly scheduled inspection that generally consists of visual observations that are needed to determine the functional condition of the bridge, and Recommend any repairs or other services that may be needed. Standard routine inspection frequency is two years. However, the NBIS requires inspections be performed annually when conditions rating of bridge is 3 or less or the bridge has an operating load rating factor of less than 1.0 for any of the legal load types (ODOT 2012). In depth evaluation of bridge is needed to supplement the visual inspection. The bridge inspector may employ either nondestructive testing techniques or destructive techniques such as chipping, drilling and core drilling which are the most common in-depth exploratory methods. Nondestructive methods need expertise that is required to interpret the results in the field. The steps for in-depth evaluation of a concrete structure are: 1. Visual Inspection with the last bridge inspection report in-hand. 2. Revision of engineering data, design, construction documentation, operation and maintenance records. 3. Revision of inspection reports and then mapping of the various deficiencies. 4. Monitoring and using nondestructive evaluation methods.  The steel location and depth of cover can be determined non-destructively using a device called a pachometer. This device measures variations in magnetic flux caused by the presence of steel. If the size of reinforcement is known, the amount of concrete cover can be determined. In general, these devices can measure cover to within ¼ inch at 0 to 3 inch from the surface. The accuracy of the devices is dependent on the amount of reinforcing steel that is present in the concrete. The more congested the reinforcing, the less accurate the device becomes. In some cases, when other bars interfere, the device cannot identify either location or depth of cover. Other techniques, such as ground-penetrating radar (GPR) or x-ray, can be used for locating steel rebars when the pachometer fails to provide the necessary information. Between GPR and x-ray, x-ray is more accurate in locating steel rebarsethod. . The corrosion of steel rebar can be determined by using the CSE methods (ODOT 2012).  The state of Oregon uses destructive in depth testing such as chloride content test, depth of carbonation and core test to determine the compressive strength of concrete. Hammer sounding and chain dragging are used to determine delamination in concrete. While these methods are not expensive, they are time consuming to perform. Petrographic analysis is a detailed examination of concrete to determine the formation and composition of the concrete and to classify its type, condition, and serviceability. Petrographic examination helps determine some of the freeze-thaw, sulfate attack and alkali-aggregate reactivity. Petrographic examination is a highly specialized practice requiring skilled and well trained technicians.The most common defects encountered in steel superstructures include Corrosion, Fatigue cracking, heat damage, and overload damage. One of the primary methods to mitigate corrosion is painting with an acceptable coating. Dye penetrate and ultrasonic are used as non-destructive evaluation methods for fracture critical members bridge inspection (ODOT 2012; FHWA 2012). 2.3 Bridge Condition Assessment In Quebec Bridges in Quebec are managed by MTQ (Manuel d’entretien des structures). Bridge condition inspections in Quebec are classified to visual examination which can be used to document and record the severity and overall condition of bridges. A photographic record of this information is essential. Some testing can supplement observations and measurements. Some of the techniques that can be used during ordinary inspections are: acoustic impact (hammer sounding, chain dragging) for detection of delamination, debonding, voids, and other defects underneath the surface; rebound hammer to evaluate the concrete strength and quality on a comparative basis. NDE methods are used for advanced 220-4 inspection. However, these methods still need more development regarding data interpretation. Using combination of visual inspection half-cell potential, acoustic methods and coring are the most widely used techniques in bridge inspection practice.   There are currently three types of bridge inspection Practice in Quebec. These are as follows: • Routine inspection:  It is a visual inspection and is done once a year where defects are observed and recorded. Routine inspection provide inspector with general knowledge about the condition of the bridge. • General Inspection: This type of inspection is more accurate type and is performed by an engineer or technician who has been trained by a regional bridge engineer. It remains a visual examination, that is supplemented by hammer sounding, general dimension measurements and crack measurements. The frequency of this inspection varies from 3 to 6 years depending on the bridge type; concrete bridges are inspected every 5 years.  -Special inspection: This type of inspection usually follows the general inspection where significant deterioration is found and when the inspector has difficulties to assess the condition. This type of inspection is carried out as requested and can be done with the help of a structural engineer. The bridge condition rating index in Quebec ranges from 1 to 6, where 1 is the lowest value and 6 is the highest: 1-critical, 2-defective, 3-mediocre, 4-acceptable, 5-good, 6-excellent and for elements that don’t exist, the index value is 0. 2.4 Bridge Condition Assessment In Ontario Ontario structure inspection management systems (OSIMS) was developed to store and manage the inspection data that is collected during the detailed structure inspections. OSIM is capable of creating, updating and storing inspection rating data for structures owned and maintained by the ministry of Transportation. The data are stored in data base and then can be used to generate reports on condition rating. The general information for a structure is obtained from Ontario structure inventory system (OSIS). In the past, inspectors relied on their background and experience in reporting bridge condition. OSIM sets standard for detailed routine inspection and condition rating for structures and their components (OSIM, 2000; Branco and de Brito, 2004). In order to classify defects, severity level should be illustrated. As an example, severity is considered light when delamination area measured is less than 150mm in any direction; medium when delamination area is between 150mm to 300mm; severe when delamination area is within 300 mm to 600 mm and very severe when area is more than 600mm. The defects are divided into material defects and performance defects. OSIM presents the material defects that are found in concrete and steel bridges and it is related to building materials regardless of any consequences to the structure. Performance defects are problem that may impact the structure as a whole. The material and performance condition rating are numerical systems in which a number from 1 to 6 is assigned to each component of the structure. Number 0 is assigned to a component when it doesn’t exist and number 9 is assigned to a component that is not visible at the time of inspection. In some cases, performance defect exists as a result of defects in design or construction. The lowest performance condition rating of primary component should be the performance condition rating of the structure (OSIM 2000; Branco and de Brito, 2004).  The inspection system in Ontario is classified into general inspection, detailed inspection and condition survey. General inspections are based on visual inspections; routine general inspection can talk place daily, monthly or annually for bridges within span over 6 m. Non routine general inspection is performed when inspection is needed for specific problem. Detailed Inspection can be routine or non-routine inspection and should be done by using measurement tools, tabs, camera and thermometers. Inspectors should review all previous inspection reports, details and all records. The inspectors should take sketches and photographs. Condition Survey inspection requires measurements and documents of all areas of defects and deterioration. It requires access to all area of the structure. Routine condition survey can be done every 5 years on selected number of structure and it incorporates the load carrying capacity assessment. For bridge deck condition survey, assessment can be done using GPR and thermograph.  220-5 Table1: Current Practice of Bridge Condition Assessment in North America CURRENT PRACTICE INSPECTION LEVEL INSPECTION TYPE INSPECTION FREQUENCY NUMERICAL RATING NDE METHODS SHORTCOMING Alberta   Level 1( Routine Inspection)       Visual Inspection       Set Up by the department.       range of 1 to 9      -        Level 1 rating is subjective.  Level2, the overall rating still not accurat, Chloride Test is time consuming, destructive test. the inspector should verify the reading.   Level2 (Specialized Inspection)   In-depth inspection    Grouped together into categories. ratings from 9-7, 6-5, 4-3, 2-1   Ultrasound for steel bridges, CSE for concrete deck. Ontario -Routine General Inspection  -Non Routine General Inspection   -Detailed Inspection -    -Condition Survey Visual Inspection   Visual Inspection  Sketches and measurement tools  In depth Inspection using load carrying capacity assessment -Daily, monthly or annually   When needed for specific problem  Two years   5 years  -       Camera, tab, thermometers   GPR and thermograph for bridge deck assessment The detailed Condition survey still use destructive methods. Use of NDT methods need high level training to interpret the results. Oregon, USA Routine Inspection     In-depth inspection -Visual Inspection     -use nondestructive methods and destructive test like core sampling, hammer and 2 years       5 years 1-9 N/A      Pachometer, X-ray and GPR   Dye penetrate and  rely on destructive methods chloride content test, and core test. Hammer sounding and chain dragging are time consuming. 220-6 chain dragging ultrasound used for critical members in steel bridges  Painting coating Used for corrosion in steel bridges.  Petrographic examination  Pachometer sometimes fail to give accurate information. Petrographic examination is requiring skilled and well trained technicians. Quebec -Routine Inspection    -General Inspection           -Special Inspection Visual Inspection   visual examination, that supplemented by hammer sounding, general dimension measurements, Coring Once a year     3 to 5 years             AS requested  range from 1 to 6, where 1 is the lowest value and 6 is the highest; 1-critical, 2-defective, 3-mediocre, 4-acceptable, 5-good, 6-excellent; for elements that don’t exist, the index value is 0 N/A    N/A           Half Cell potential and Acoustic methods The condition rating values cannot be used to evaluate the structural capacity of the element. These values are used for general condition of the structure. Also, the special inspectin is not clearly defined..  3 CURRENT PRACTICE IN BRIDGE CONDITION ASSESSMENT OUTSIDE NORTH AMERICA 3.1 Bridge Condition Assessment In United Kingdom In United Kingdom, bridges are subjected to general inspection every 2 years and to more principal inspection every 6-10 years. These inspections are visual inspection that record only damage or deterioration that are seen. Defects that have main concern are inspected within special inspection, such as half -cell potential and cores sampling are examined to check the presence of alkali reaction. Special inspection measures the depth of concrete cover, carbonation, chloride, sulfate contents. The condition of each element is given a rating on scale of 1 to 5 at the time of inspection based. Each element is given a location factor based on its structural importance. The overall condition rating of bridge is given using the equation 2  220-7 ( ) ( ) ××+×××=NsSfEfsF3NpSfEfpF2f1-100BCI ………………………………………………..EQ2 Where, Efp is element factor from 1 to 10 of primary element, Efs is element factor of secondary elements, Sf = The extent of damage / Severity factor 1- 10, Np is the number of primary elements, Ns is the number of secondary elements and F1, F2 and F3 are the severity factors. Superstructure and substructure are both divided into a number of elements and receive score of 1 to 8. The element rating percentage can be calculated from EQ2. The overall condition rating for substructure and superstructure is taken as the lowest element rating. Bridge condition assessment in UK has some shortcoming as there is little use of nondestructive evaluation methods and there is no relationship between bridge age and maintenance cost. Current practice with countries outside North America are illustrated in Table 2   Table 2: Current Practice outside North America   CURRENT PRACTICE INSPECTION LEVEL INSPECTION PRINCIBALE INSPECTION FREQUENCY     NUMERICAL RATING UK General Inspection   Principal Inspection Visual Inspection     In depth inspection 2 years     6-10years range of 1 to 5, overall condition rating is taken as the lowest element   Half-cell potential test      Denmark -Routine superficial Inspection  -Principal Inspection  -Technical Inspection Visual Inspection    Visual Inspection   More investigation. In depth Inspection using load carrying capacity  - Annually    -3 years      Final condition rating is based on bearing capacity and importance of each element Portugal -Ordinary Inspection     Principal inspection -Visual Inspection     -Visual inspection and simple use of nondestructive methods 3 to 6 years      3 years 1-7 defect rating 1-The defect degree doesn’t increase. 2-doesnot require intervention 3-getting evolving 4-require not urgently intervention 5-doesnot influence structure  6-doesnot impair structural safety 7-it reduces safety coefficient Sweden -Regular Inspection   -Superficial Inspection   -General Inspection Visual Inspection    Visual Inspection    Done by well-trained inspector Quick monthly   Each 1 year     3 years  -Degree of urgency 0 to 2 0-no action required 1-The same within 1 year 2-action require within 3 years  -Defect Rating 0 to 3 0-gurantee for next 10 years,1-gurantee for next 3-10 years, 2-same before 3years,3-defective function found, Ultrasound and 220-8  -Major Inspection  Complete examination  6 years radiography. Australia -Level1 Inspection  -Level2 Inspection  -Level3 Inspection -Visual Inspection   -Visual Inspection   In-depth Inspection  Ground Penetrating Radar and impact echo are used to determine voids .Ultrasonic Pulse Velocity is used to determine cracks, concrete strength, location of reinforcement can be measured using GPR. Half-cell potential used to detect steel corrosion and rebound hammer for concrete strength. Steel brides deterioration can be determined by using Eddy current, Dye penetrates Radiographic and ultrasonic testing. Concrete cover can be measured also using cover meter.  4 SUMARRY AND CONCLUSION The current practice for bridge condition assessment and inspection in Alberta has some limitations.  For example their Level 1 inspection is visual and the rating is subjective and depends on the inspector experience. Level 2 inspection, the overall rating might not be accurate as the areas that are not visible cannot be accurately assessed. In Level 2 inspection, chloride test is used to determine the chloride content in concrete. This test is time consuming and destructive test. When CSE test is used in level 2, the inspector should stop when reading is getting so high or low, and verify the validity of the ground connection or check if the deck is not wet enough for accurate results. CSE test can determine the presence of corrosion but cannot determine the corrosion rate. The state of Oregon still rely on destructive methods where samples should be taken in specific positions from the bridge to perform in depth inspection  such as chloride content test, depth of carbonation and core test. Hammer sounding and chain dragging are time consuming. Pachometer that used for depth of cover measurements sometimes fail to give accurate information. Petrographic examination is a highly specialized practice requiring skilled and well trained technicians. The current practice in Quebec has some of shortcoming. The condition rating values cannot be used to evaluate the structural capacity of the element. These values are used for general condition of the structure and for evaluation of deterioration. Also, the special inspection is not clearly defined and the system that is followed for reporting is not provided. Inspectors and engineers should be well trained; they should increase their knowledge regarding the material behavior. General inspection is still visual inspection without condition evaluation for specific elements. Special inspections should include in-depth condition evaluation including load-carrying capacity evaluation. Inspection system outside North America is based on number of visits to the bridge at fixed time interval which is called periodic; the other type of inspection that is not based on interval is called non periodic inspection. The general system of inspection is classified into: superficial inspection that usually done every one year; it is visual inspection with portable support measurements. Through inspection which is called detailed inspection and usually done within period equal to a multiple of the superficial inspection; it is checkup of the structure with detailed visual inspection and usually done with inspector with high 220-9 experience. Special inspection is usually not periodic inspection; it is done based on specific defects that was detected; this inspection usually done using specialized equipment and test with the use of NDE methods. Bridge condition assessment in other countries is almost the same. Bridge inspection levels are classified according to inspection interval where the inspection intensity varies with inspection interval. There are three levels of inspection that are defined based on the interval: Short interval check of safety, medium interval of maintenance needs and long intervals, in depth assessment. Identifications of repairs needed are identified during the inspection within medium interval. Inspection with less interval are used together with the inspection of long interval. There is less use on non-destructive evaluation methods in the special inspection. However, MRWA Australian manual is incorporating the use of many NDT methods. References American Society of Civil Engineer, 2013, Infrastructure report card.           www.infrastructurereportcard.org/bridges FHWA. 2012. Bridge Inspector’s Refrence, Manual, U.S.  Department of Transportation, Federal Highway Administration, Washington, D.C., USA Rens, K. L., Nogueira, C. L., and Transue, D. J. 2005. Bridge Management and Nondestructive Evaluation. Journal of:  Performance of Constructed Facilities, 19: 3-16. SHRP2. 2009. A Plan for Developing High-Speed Nondestructive Testing Procedures for Both Design Evaluation and Construction Inspection, Transportation Research Board, Washington, D.C., USA. SHRP2. 2013. Nondestructive Testing to Identify Concrete Bridge Deck Deterioration, Transportation Research Board, Washington, D.C., USA. Wang, Y. M., Liu, J., Elhag, T. M.S. 2008. An integrated AHP–DEA methodology for bridge risk assessment. Journal of: Computer and industrial Engineering, 54: 513-525. Xia, P. Q. and Brownjohn, J. M. W. 2004. Bridge Structural Condition Assessment Using Systematically Validated Finite-Element Model. Journal of: Bridge Engineering, 9 : 418-423. Hearn, George. Bridge inspection practices. Vol. 375. Transportation Research Board, 2007. Ministry of Transportation, “Ontario Structure In-spection manual”, 2000, Policy, Planning & Standards  Division, Engineering Standard branch,   220-10  5th International/11th Construction Specialty Conference 5e International/11e Conférence spécialisée sur la construction    Vancouver, British Columbia June 8 to June 10, 2015 / 8 juin au 10 juin 2015   COMPARITIVE STUDY OF CURRENT PRACTICE IN BRIDGE CONDITION ASSESSMENT Marwa H. Ahmed1,2,  Anjan. Bhowmick1 and Osama. Moselhi1 1 Building, Civil, and Environmental Engineering Dept., Concordia University, Canada. 2 mar_ahme@encs.concordia.ca Abstract: Bridges play a vital role in road infrastructure networks. According to Statistics Canada, bridges and overpasses accounted for 8% of total public assets in 2007.. Ontario ranked as the third among provinces in terms of having old bridges. In 2007, Bridges in Ontario accounted for 7% of its public infrastructure, while in Alberta, bridges account for 9% of total public infrastructure. Bridge condition assessment is conducted to determine load rating capacity for bridge elements. The identification of current condition of each element provides early warning of necessary maintenance. Condition rating is performed during the inspection process. This paper provides a comparative study of current practices in bridge condition rating worldwide, with emphasis on the United States and Canada. The study includes 4 main criteria: inspection levels, inspection principles, inspection frequencies and numerical ratings for 4 provinces in North America: Alberta, Ontario, Quebec and state of Oregon and 5 countries outside North America: United Kingdom, Denmark, Portugal, Sweden and Australia. The Limitations of current practices are discussed and recommendations for improved inspection are provided. The study is expected to assist professionals and inspectors in selecting feasible method/s for effective bridge condition assessment.  1 INTRODUCTION Bridge Management System (BMS) is the process of monitoring, inspection, repair and replacement of deteriorated bridges. All bridge management decisions require inspection data to identify current condition of bridges. Moreover, it provides decision making with tools to select the appropriate solution, such as bridge rehabilitation or replacement. BMS is facing imbalance between the need for repairs or replacements and many challenges due to incorporating of multi objectives; structural safety, serviceability, optimum maintenance and economic considerations. Therefore, BMS cannot make decisions without accurate and detailed data of bridge conditions. Thus, decision makers can avoid the worst consequences of underestimating the degree of deterioration and avoid the costly consequences of overestimating the degree of deterioration. The main goal of BMS is to gain the maximum performance with using minimum cost and this can be achieved by efficient techniques and technologies that can be automatically updated. Consequently, the service life of bridges can be increased within effective cost. (Rens et al. 2005; Steart et al. 2002, Wang et al.2007). Structural health monitoring, inspection process and condition assessment are considered main components of BMS.  Bridge condition assessment is conducted to determine load rating capacity for bridge components. The main components of bridges are deck, superstructure and substructure. Each component has different role in bridge structure with specified relative importance. Bridge condition assessment defines the 220-1 structural importance of each bridge element. The identification of current condition of each element provides with early warning of necessary maintenance. The main difficulty in bridge condition assessment is the large number of bridges in the network which requires regular inspection. However, condition rating is performed using the inspection data. These collected data are converted to a rating to assess bridge condition (Xia and Brownjohn, 2004; Yehia et al. 2007). This paper presents a detailed comparison of current practices of condition assessment of bridge structures in different countries.  2 CURRENT PRACTICE IN BRIDGE CONDITION ASSESSMENT  IN NORTH AMERICA According to Federal Bridge Inspection Standard (FBIS), the levels of service deficiencies are based on comparisons of the actual load capacity of bridge with the level of service. The evaluation of bridge condition deficiency (BCD) includes an assessment of the condition of each of the three primary elements of the bridge: Super structure (SPD), Substructure (SBD) and bridge deck (BDD). After the total deficiency has been established for all bridges, costs associated with replacement and rehabilitation should be determined (FHWA, 2012; Branco and de Brito, 2004).  BCD= SPD+ SBD+ BDD……………………………………………………………………Eq.1  Condition ratings for each element of the bridge are assigned every two years and are then aggregated into overall condition ratings for super, sub structure and deck, the ratings are numerical values from 0 to 9. Bridges are considered structurally deficient if any of deck, substructure or superstructure is equal or less than 4 (poor). If the structural evaluation is equal or less than 2, then the bridge is having high priority for replacement ( FHWA, 2012; Branco and de Brito, 2004). According to the manual for maintenance inspection, AASHTO describes two basic load rating procedures: (1) the allowable stress, (2) Load rating, LR. In the United States, bridges are periodically rated according to their structural capacity. The rating can actually increase with time in bridges inspected regularly with maintenance programs, where the live load limits are checked by traffic police 2.1 Bridge Condition Assessment In Alberta Transportation According to Bridge Inspection Manual of Alberta Transportation, the condition rating system in Alberta consists of a numerical rating range of 1 to 9 (BIM 2004;  Branco and de Brito 2004). This rating applies to all inspection elements as well as the general rating for each category. The rating is representative of the condition of the element and the ability of the element to function as originally designed. Bridge can be rated 9 if it is in excellent condition. Additionally, the rating of the element also reflects any safety concerns and maintenance priority. The rating of an element is determined by the rating of the worst item within the group. The inspector should describe, and explain the condition, why the post has a low rating and where it is located.   The rating of the element is visual inspection and based on what the inspector can see. The inspector should be able to see enough of the element to be comfortable assigning a rating. If the element is inaccessible or is not visible for the inspector to assign a rating, the element is rated ‘N’. If a particular element does not apply to the structure being inspected, the element is rated ‘X’. In situations where an element does not exist but is required in the judgment of the inspector, the element is rated ‘X’ with a comment provided in the ‘Explanation of Condition’ section which illustrates within a maintenance recommendation (BIM 2004 ). The general rating for each category is determined by the ratings assigned to critical load carrying elements or members of the structure. The general rating must also reflect any safety concerns related to the function of the structure. The general rating is not an average of the element ratings; as the general rating cannot be higher than the lowest critical element rating.  All bridges are to be inspected in accordance with the following intervals to ensure an appropriate level of safety: major bridges, Standard bridges, in highways with numbers less than 500 or greater than or equal to 900 are within 21 months interval. Major bridges, standard bridges in highways with numbers equal to or greater than 500 but less than 900 are within 39 months interval. Major bridges in parks that carry pedestrian traffic only are inspected within 57 months interval. All new bridge structures are to be inspected immediately after construction is complete and within 24 months after completion. All bridge 220-2 structures are to be inspected immediately after any significant maintenance or rehabilitation is completed. The inspector may specify shorter intervals depending on the age, traffic characteristics and known deficiencies (BIM 2004;  Branco and de Brito, 2004).  Most major bridges, standard bridges, are inspected by a certified bridge inspector on a routine basis which is known as Level 1 inspection. However, certain major bridges or components of standard bridges require inspection with specialized knowledge, tools and equipment. Almost all bridges will require specialized inspections which are known as Level 2 inspections. Specialized inspection includes ultrasonic tests on steel bridges, CSE tests on deck concrete, coring test. Level 2 inspections are essential for high load and overload damage, or where critical or significant deficiencies are determined (BIM 2004;  Branco and de Brito, 2004) . Level 1 is a general inspection which requires completion of the BIM report and use of basic tools and equipment. This level of inspection must be undertaken by certified bridge inspectors. Level 1 inspections are general visual inspections conducted using standard tools and equipment. This level must be performed at time intervals not exceeding those specified by Department policy. Level 1 inspection rate the worst part of each element and do not take the overall element condition into account.  Level 2 inspection is an in-depth inspection which requires completion of the BIM report, and use of specialized tools, techniques, and equipment. Level 2 inspections are quantitative inspections conducted using specialized tools. This level of inspection gathers detailed information on the condition of a particular bridge. In Alberta, concrete deck inspections are currently performed on approximately 120 bridge sites per year throughout Alberta on a 4 to 5 year inspection cycle. Additional Level 2 deck inspections may be completed as part of a bridge assessment that identified in a previous Level 1 inspection. The quantified condition data that are collected provide information on the element and this condition can be monitored over time. The condition rating for Level 2 inspections are grouped together into categories. Therefore ratings from 9-7 are grouped as very good condition ratings, and then ratings 6 and 5 are grouped as adequate ratings. Ratings of 4 and 3 are grouped as ratings that are the most critical and give priority of the element. Ratings of 2 and 1 are grouped as these ratings are required immediate maintenance or repair. The inspector should rate the general condition and not just the worst case. The inspector should note that if the damage is significant to the structural capacity.   Level 1 rating should be used to reflect the worst damage to the element. A rating of 5 or higher is for elements that are functioning as designed. For a rating of 5 an element may have minor structural flaws, but these flaws should not impact the structural capacity of the member. A rating of 4 is a low maintenance priority, and these elements would generally be scheduled for repair in more than 3 years. A rating of 3 is a medium priority for maintenance, as repairs would typically be scheduled from 6 months to 3 years away. A rating of 2 is a high priority for maintenance and repairs would likely be less than 6 months away. A rating of 1 requires urgent and immediate action.  The Chloride Test is a field test to determine the chloride content of concrete.  It is most often performed on a deck because these are the areas of the bridge that are commonly exposed to the de-icing salt. This test is performed in level 2 inspection. Chloride testing is destructive because holes are drilled into the component that is being tested. This testing is also time-consuming as the samples must be extracted and tested. The destructive and time-consuming nature of the test means that only a limited number of samples can be gathered and tested. Copper Sulfate Electrode (CSE) test is a repeatable, non-destructive field test. Alberta Transportation remains one of the few agencies that use CSE testing as a predictive tool for preventative maintenance programs. CSE testing, also referred to as half-cell testing is used to determine the potential of corrosion in reinforcing steel, but they do not indicate a corrosion rate. Test results from one year to another are compared to assess the advancement of corrosion and predict the future deck condition. The CSE data are used to develop prediction models and to determine the ideal time to rehabilitate a deck. CSE data is also used to evaluate the effectiveness of various rehabilitation methods. CSE testing is quick, and cost-effective. The limitation of CSE testing is that, suddenly the readings become higher, lower, as the ground connection may be broken, the voltmeter connections may have worked loose, or the grounding wire may be broken. In this case, inspector should stop and verify the validity of the ground connection or check if the deck is not wet enough for accurate results. 220-3 2.2 Bridge Condition Assessment in State of Oregon, USA The Oregon department of transportation (ODOT) considers the routine inspection report to be the primary tool for reporting the condition of a structure. The routine inspection report is a summary of condition assessment data that is generated via a number of more detailed types of inspections. A Routine Bridge Inspection is a regularly scheduled inspection that generally consists of visual observations that are needed to determine the functional condition of the bridge, and Recommend any repairs or other services that may be needed. Standard routine inspection frequency is two years. However, the NBIS requires inspections be performed annually when conditions rating of bridge is 3 or less or the bridge has an operating load rating factor of less than 1.0 for any of the legal load types (ODOT 2012). In depth evaluation of bridge is needed to supplement the visual inspection. The bridge inspector may employ either nondestructive testing techniques or destructive techniques such as chipping, drilling and core drilling which are the most common in-depth exploratory methods. Nondestructive methods need expertise that is required to interpret the results in the field. The steps for in-depth evaluation of a concrete structure are: 1. Visual Inspection with the last bridge inspection report in-hand. 2. Revision of engineering data, design, construction documentation, operation and maintenance records. 3. Revision of inspection reports and then mapping of the various deficiencies. 4. Monitoring and using nondestructive evaluation methods.  The steel location and depth of cover can be determined non-destructively using a device called a pachometer. This device measures variations in magnetic flux caused by the presence of steel. If the size of reinforcement is known, the amount of concrete cover can be determined. In general, these devices can measure cover to within ¼ inch at 0 to 3 inch from the surface. The accuracy of the devices is dependent on the amount of reinforcing steel that is present in the concrete. The more congested the reinforcing, the less accurate the device becomes. In some cases, when other bars interfere, the device cannot identify either location or depth of cover. Other techniques, such as ground-penetrating radar (GPR) or x-ray, can be used for locating steel rebars when the pachometer fails to provide the necessary information. Between GPR and x-ray, x-ray is more accurate in locating steel rebarsethod. . The corrosion of steel rebar can be determined by using the CSE methods (ODOT 2012).  The state of Oregon uses destructive in depth testing such as chloride content test, depth of carbonation and core test to determine the compressive strength of concrete. Hammer sounding and chain dragging are used to determine delamination in concrete. While these methods are not expensive, they are time consuming to perform. Petrographic analysis is a detailed examination of concrete to determine the formation and composition of the concrete and to classify its type, condition, and serviceability. Petrographic examination helps determine some of the freeze-thaw, sulfate attack and alkali-aggregate reactivity. Petrographic examination is a highly specialized practice requiring skilled and well trained technicians.The most common defects encountered in steel superstructures include Corrosion, Fatigue cracking, heat damage, and overload damage. One of the primary methods to mitigate corrosion is painting with an acceptable coating. Dye penetrate and ultrasonic are used as non-destructive evaluation methods for fracture critical members bridge inspection (ODOT 2012; FHWA 2012). 2.3 Bridge Condition Assessment In Quebec Bridges in Quebec are managed by MTQ (Manuel d’entretien des structures). Bridge condition inspections in Quebec are classified to visual examination which can be used to document and record the severity and overall condition of bridges. A photographic record of this information is essential. Some testing can supplement observations and measurements. Some of the techniques that can be used during ordinary inspections are: acoustic impact (hammer sounding, chain dragging) for detection of delamination, debonding, voids, and other defects underneath the surface; rebound hammer to evaluate the concrete strength and quality on a comparative basis. NDE methods are used for advanced 220-4 inspection. However, these methods still need more development regarding data interpretation. Using combination of visual inspection half-cell potential, acoustic methods and coring are the most widely used techniques in bridge inspection practice.   There are currently three types of bridge inspection Practice in Quebec. These are as follows: • Routine inspection:  It is a visual inspection and is done once a year where defects are observed and recorded. Routine inspection provide inspector with general knowledge about the condition of the bridge. • General Inspection: This type of inspection is more accurate type and is performed by an engineer or technician who has been trained by a regional bridge engineer. It remains a visual examination, that is supplemented by hammer sounding, general dimension measurements and crack measurements. The frequency of this inspection varies from 3 to 6 years depending on the bridge type; concrete bridges are inspected every 5 years.  -Special inspection: This type of inspection usually follows the general inspection where significant deterioration is found and when the inspector has difficulties to assess the condition. This type of inspection is carried out as requested and can be done with the help of a structural engineer. The bridge condition rating index in Quebec ranges from 1 to 6, where 1 is the lowest value and 6 is the highest: 1-critical, 2-defective, 3-mediocre, 4-acceptable, 5-good, 6-excellent and for elements that don’t exist, the index value is 0. 2.4 Bridge Condition Assessment In Ontario Ontario structure inspection management systems (OSIMS) was developed to store and manage the inspection data that is collected during the detailed structure inspections. OSIM is capable of creating, updating and storing inspection rating data for structures owned and maintained by the ministry of Transportation. The data are stored in data base and then can be used to generate reports on condition rating. The general information for a structure is obtained from Ontario structure inventory system (OSIS). In the past, inspectors relied on their background and experience in reporting bridge condition. OSIM sets standard for detailed routine inspection and condition rating for structures and their components (OSIM, 2000; Branco and de Brito, 2004). In order to classify defects, severity level should be illustrated. As an example, severity is considered light when delamination area measured is less than 150mm in any direction; medium when delamination area is between 150mm to 300mm; severe when delamination area is within 300 mm to 600 mm and very severe when area is more than 600mm. The defects are divided into material defects and performance defects. OSIM presents the material defects that are found in concrete and steel bridges and it is related to building materials regardless of any consequences to the structure. Performance defects are problem that may impact the structure as a whole. The material and performance condition rating are numerical systems in which a number from 1 to 6 is assigned to each component of the structure. Number 0 is assigned to a component when it doesn’t exist and number 9 is assigned to a component that is not visible at the time of inspection. In some cases, performance defect exists as a result of defects in design or construction. The lowest performance condition rating of primary component should be the performance condition rating of the structure (OSIM 2000; Branco and de Brito, 2004).  The inspection system in Ontario is classified into general inspection, detailed inspection and condition survey. General inspections are based on visual inspections; routine general inspection can talk place daily, monthly or annually for bridges within span over 6 m. Non routine general inspection is performed when inspection is needed for specific problem. Detailed Inspection can be routine or non-routine inspection and should be done by using measurement tools, tabs, camera and thermometers. Inspectors should review all previous inspection reports, details and all records. The inspectors should take sketches and photographs. Condition Survey inspection requires measurements and documents of all areas of defects and deterioration. It requires access to all area of the structure. Routine condition survey can be done every 5 years on selected number of structure and it incorporates the load carrying capacity assessment. For bridge deck condition survey, assessment can be done using GPR and thermograph.  220-5 Table1: Current Practice of Bridge Condition Assessment in North America CURRENT PRACTICE INSPECTION LEVEL INSPECTION TYPE INSPECTION FREQUENCY NUMERICAL RATING NDE METHODS SHORTCOMING Alberta   Level 1( Routine Inspection)       Visual Inspection       Set Up by the department.       range of 1 to 9      -        Level 1 rating is subjective.  Level2, the overall rating still not accurat, Chloride Test is time consuming, destructive test. the inspector should verify the reading.   Level2 (Specialized Inspection)   In-depth inspection    Grouped together into categories. ratings from 9-7, 6-5, 4-3, 2-1   Ultrasound for steel bridges, CSE for concrete deck. Ontario -Routine General Inspection  -Non Routine General Inspection   -Detailed Inspection -    -Condition Survey Visual Inspection   Visual Inspection  Sketches and measurement tools  In depth Inspection using load carrying capacity assessment -Daily, monthly or annually   When needed for specific problem  Two years   5 years  -       Camera, tab, thermometers   GPR and thermograph for bridge deck assessment The detailed Condition survey still use destructive methods. Use of NDT methods need high level training to interpret the results. Oregon, USA Routine Inspection     In-depth inspection -Visual Inspection     -use nondestructive methods and destructive test like core sampling, hammer and 2 years       5 years 1-9 N/A      Pachometer, X-ray and GPR   Dye penetrate and  rely on destructive methods chloride content test, and core test. Hammer sounding and chain dragging are time consuming. 220-6 chain dragging ultrasound used for critical members in steel bridges  Painting coating Used for corrosion in steel bridges.  Petrographic examination  Pachometer sometimes fail to give accurate information. Petrographic examination is requiring skilled and well trained technicians. Quebec -Routine Inspection    -General Inspection           -Special Inspection Visual Inspection   visual examination, that supplemented by hammer sounding, general dimension measurements, Coring Once a year     3 to 5 years             AS requested  range from 1 to 6, where 1 is the lowest value and 6 is the highest; 1-critical, 2-defective, 3-mediocre, 4-acceptable, 5-good, 6-excellent; for elements that don’t exist, the index value is 0 N/A    N/A           Half Cell potential and Acoustic methods The condition rating values cannot be used to evaluate the structural capacity of the element. These values are used for general condition of the structure. Also, the special inspectin is not clearly defined..  3 CURRENT PRACTICE IN BRIDGE CONDITION ASSESSMENT OUTSIDE NORTH AMERICA 3.1 Bridge Condition Assessment In United Kingdom In United Kingdom, bridges are subjected to general inspection every 2 years and to more principal inspection every 6-10 years. These inspections are visual inspection that record only damage or deterioration that are seen. Defects that have main concern are inspected within special inspection, such as half -cell potential and cores sampling are examined to check the presence of alkali reaction. Special inspection measures the depth of concrete cover, carbonation, chloride, sulfate contents. The condition of each element is given a rating on scale of 1 to 5 at the time of inspection based. Each element is given a location factor based on its structural importance. The overall condition rating of bridge is given using the equation 2  220-7 ( ) ( ) ××+×××=NsSfEfsF3NpSfEfpF2f1-100BCI ………………………………………………..EQ2 Where, Efp is element factor from 1 to 10 of primary element, Efs is element factor of secondary elements, Sf = The extent of damage / Severity factor 1- 10, Np is the number of primary elements, Ns is the number of secondary elements and F1, F2 and F3 are the severity factors. Superstructure and substructure are both divided into a number of elements and receive score of 1 to 8. The element rating percentage can be calculated from EQ2. The overall condition rating for substructure and superstructure is taken as the lowest element rating. Bridge condition assessment in UK has some shortcoming as there is little use of nondestructive evaluation methods and there is no relationship between bridge age and maintenance cost. Current practice with countries outside North America are illustrated in Table 2   Table 2: Current Practice outside North America   CURRENT PRACTICE INSPECTION LEVEL INSPECTION PRINCIBALE INSPECTION FREQUENCY     NUMERICAL RATING UK General Inspection   Principal Inspection Visual Inspection     In depth inspection 2 years     6-10years range of 1 to 5, overall condition rating is taken as the lowest element   Half-cell potential test      Denmark -Routine superficial Inspection  -Principal Inspection  -Technical Inspection Visual Inspection    Visual Inspection   More investigation. In depth Inspection using load carrying capacity  - Annually    -3 years      Final condition rating is based on bearing capacity and importance of each element Portugal -Ordinary Inspection     Principal inspection -Visual Inspection     -Visual inspection and simple use of nondestructive methods 3 to 6 years      3 years 1-7 defect rating 1-The defect degree doesn’t increase. 2-doesnot require intervention 3-getting evolving 4-require not urgently intervention 5-doesnot influence structure  6-doesnot impair structural safety 7-it reduces safety coefficient Sweden -Regular Inspection   -Superficial Inspection   -General Inspection Visual Inspection    Visual Inspection    Done by well-trained inspector Quick monthly   Each 1 year     3 years  -Degree of urgency 0 to 2 0-no action required 1-The same within 1 year 2-action require within 3 years  -Defect Rating 0 to 3 0-gurantee for next 10 years,1-gurantee for next 3-10 years, 2-same before 3years,3-defective function found, Ultrasound and 220-8  -Major Inspection  Complete examination  6 years radiography. Australia -Level1 Inspection  -Level2 Inspection  -Level3 Inspection -Visual Inspection   -Visual Inspection   In-depth Inspection  Ground Penetrating Radar and impact echo are used to determine voids .Ultrasonic Pulse Velocity is used to determine cracks, concrete strength, location of reinforcement can be measured using GPR. Half-cell potential used to detect steel corrosion and rebound hammer for concrete strength. Steel brides deterioration can be determined by using Eddy current, Dye penetrates Radiographic and ultrasonic testing. Concrete cover can be measured also using cover meter.  4 SUMARRY AND CONCLUSION The current practice for bridge condition assessment and inspection in Alberta has some limitations.  For example their Level 1 inspection is visual and the rating is subjective and depends on the inspector experience. Level 2 inspection, the overall rating might not be accurate as the areas that are not visible cannot be accurately assessed. In Level 2 inspection, chloride test is used to determine the chloride content in concrete. This test is time consuming and destructive test. When CSE test is used in level 2, the inspector should stop when reading is getting so high or low, and verify the validity of the ground connection or check if the deck is not wet enough for accurate results. CSE test can determine the presence of corrosion but cannot determine the corrosion rate. The state of Oregon still rely on destructive methods where samples should be taken in specific positions from the bridge to perform in depth inspection  such as chloride content test, depth of carbonation and core test. Hammer sounding and chain dragging are time consuming. Pachometer that used for depth of cover measurements sometimes fail to give accurate information. Petrographic examination is a highly specialized practice requiring skilled and well trained technicians. The current practice in Quebec has some of shortcoming. The condition rating values cannot be used to evaluate the structural capacity of the element. These values are used for general condition of the structure and for evaluation of deterioration. Also, the special inspection is not clearly defined and the system that is followed for reporting is not provided. Inspectors and engineers should be well trained; they should increase their knowledge regarding the material behavior. General inspection is still visual inspection without condition evaluation for specific elements. Special inspections should include in-depth condition evaluation including load-carrying capacity evaluation. Inspection system outside North America is based on number of visits to the bridge at fixed time interval which is called periodic; the other type of inspection that is not based on interval is called non periodic inspection. The general system of inspection is classified into: superficial inspection that usually done every one year; it is visual inspection with portable support measurements. Through inspection which is called detailed inspection and usually done within period equal to a multiple of the superficial inspection; it is checkup of the structure with detailed visual inspection and usually done with inspector with high 220-9 experience. Special inspection is usually not periodic inspection; it is done based on specific defects that was detected; this inspection usually done using specialized equipment and test with the use of NDE methods. Bridge condition assessment in other countries is almost the same. Bridge inspection levels are classified according to inspection interval where the inspection intensity varies with inspection interval. There are three levels of inspection that are defined based on the interval: Short interval check of safety, medium interval of maintenance needs and long intervals, in depth assessment. Identifications of repairs needed are identified during the inspection within medium interval. Inspection with less interval are used together with the inspection of long interval. There is less use on non-destructive evaluation methods in the special inspection. However, MRWA Australian manual is incorporating the use of many NDT methods. References American Society of Civil Engineer, 2013, Infrastructure report card.           www.infrastructurereportcard.org/bridges FHWA. 2012. Bridge Inspector’s Refrence, Manual, U.S.  Department of Transportation, Federal Highway Administration, Washington, D.C., USA Rens, K. L., Nogueira, C. L., and Transue, D. J. 2005. Bridge Management and Nondestructive Evaluation. Journal of:  Performance of Constructed Facilities, 19: 3-16. SHRP2. 2009. A Plan for Developing High-Speed Nondestructive Testing Procedures for Both Design Evaluation and Construction Inspection, Transportation Research Board, Washington, D.C., USA. SHRP2. 2013. Nondestructive Testing to Identify Concrete Bridge Deck Deterioration, Transportation Research Board, Washington, D.C., USA. Wang, Y. M., Liu, J., Elhag, T. M.S. 2008. An integrated AHP–DEA methodology for bridge risk assessment. Journal of: Computer and industrial Engineering, 54: 513-525. Xia, P. Q. and Brownjohn, J. M. W. 2004. Bridge Structural Condition Assessment Using Systematically Validated Finite-Element Model. Journal of: Bridge Engineering, 9 : 418-423. Hearn, George. Bridge inspection practices. Vol. 375. Transportation Research Board, 2007. Ministry of Transportation, “Ontario Structure In-spection manual”, 2000, Policy, Planning & Standards  Division, Engineering Standard branch,   220-10  1	  COMPARITIVE STUDY OF CURRENT PRACTICE IN BRIDGE CONDITION ASSESSMENT  Vancouver, Canada,  June 8-10, 2015 Marwa	  Hussein,	  Anjan	  Bhowmick	  and	  Osama	  Moselhi	  PRESENTATION OUTLINE	  2	  INTRODUCTION RESEARCH OBJECTIVES METHODOLOGY FINDINGS OF THE STUDY 	  	  	  	  	  	  	  	  	  	  INTRODUCTION 3	  Bridge Management System (BMS) requires accurate collection of data pertinent to bridge conditions Bridge condition Assessment provides decision makers with tools to select the appropriate solution, such as bridge rehabilitation or replacement	  The main difficulty in bridge condition assessment is the large number of bridges in the network, lack of fund and shortage of manpower	  	  OBJECTIVES 4	  -­‐	  	  	  	  Provides an overview of current practices in bridge inspection comparative study of current practices in bridge condition rating worldwide, with emphasis on the United States and Canada 	  Scope of the study 5	  Current Practice State of Oregon Inside North America Outside North America Ontario Alberta Quebec UK Portugal Denmark Australia Sweden Condition assessment  6	     Main Criteria Inspection Level Inspection Principle Inspection Frequency Numerical Rating Current Practice - North America Current Practice Inspection Level 	  Inspection Type Inspection Frequency Numerical Rating   ALBERTA Level 1 ( Routine    Inspection) 	  Visual  Inspection Set up By the Department 1 to 9 Level2 (Specialized Inspection In-Depth  Inspection Set up By the Department  Categories. ratings from 9-7, 6-5, 4-3, 2-1   ONTARIO Routine Inspection 	  Visual Inspection  Daily, monthly or annually 1 to 6 	  Non Routine Inspection Visual Inspection  When required - 	  Detailed Inspection Sketches measurement Two Years  1 to 6 	  Condition Survey In-Depth  Inspection  Five Years - 	  8	  Current Practice - North America Current Practice Current Practice Inspection Level 	  Inspection Type Inspection Frequency Numerical Rating   State of OREGON Level 1 Routine    Inspection 	  Visual  Inspection 2 Years 1 to 9 Level2 Inspection In-Depth  Inspection 5 Years,            -   QUEBEC Routine Inspection 	  Visual Inspection  Once  a Year 1 to 6 	  General Inspection Visual Examination, destructive test  3 to 5 Years - 	  Special Inspection Sketches measurement As Required  1 to 6 	  9	  Current Practice outside North America Current Practice Inspection Level 	  Inspection Type Inspection Frequency Numerical Rating  United Kingdom General Inspection 	  Visual  Inspection 2 Years 1 to 5 Principal Inspection In-Depth  Inspection 6-10 Years,           1 to 5   Denmark Routine superficial Inspection	  Visual Inspection  Annually Final condition rating is based on Principal Inspection Visual with investigation inspection  3 Years  importance of  element   Technical Inspection In-Depth  Inspection As Required  - 	  10	  Current Practice outside North America Current Practice Inspection Level 	  Inspection Type Inspection Frequency Numerical Rating   PORTUGAL Ordinary Inspection 	  Visual  Inspection 3 to 6 Years 1 to 7 Principal Inspection Visual   Inspection and tests 3 Years          1 to 7  SWEDEN Regular Inspection 	  Visual Inspection  Quick visit monthly 0 to 2 	  Superficial Inspection Visual Inspection  Once a year - 	  General Inspection well trained inspector 3 Years  0 to 3 	  Major Inspection Complete Examination  6 Years - 	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  	  Observed Limitations  11	  	  	  CURRENT PRACTICE SHORTCOMING  ALBERTA Level 1 is visual inspection, subjective. Chloride test is time consuming. CSE test, reading should be verified ONTARIO The detailed condition survey use destructive methods. Interpretation of NDE results requires training 12	        Shortcoming of Current Practice CURRENT PRACTICE SHORTCOMING  STATE of OREGON Chloride test, depth of carbonation and core tests are destructive. Hammer sound and chain dragging are time consuming.   QUEBEC Load carrying capacity and material behavior are not included in the inspection. In depth inspection is not clearly defined 13	   Characteristics of Current Practice Outside North-America   There are three levels of inspection : Short interval check of safety, medium interval of maintenance needs and long intervals.   There is less use on nondestructive evaluation methods in the special inspection.    MRWA Australian manual incorporates the use of NDT methods.  FINDINGS	  of	  The	  Study	  Integration of Different NDE Methods is recommended in level 2 inspection The main Challenges of Using NDE Methods is Interpretation of results Condition driven frequency 	  	  	  Thank	  You	  15	  

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