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UBC Theses and Dissertations

Sustainability evaluation of transportation infrastructure under uncertainty : a fuzzy-based approach Umer, Adil


The construction and maintenance of transportation infrastructure consume significant natural resources, produces considerable waste and uses extensive human capital. Sustainability evaluation of alternative initiatives and policies for developing transportation infrastructure enables decision makers to make informed choices. Despite the availability of numerous sustainability rating tools for roadway infrastructure, there is a need to develop customizable sustainability evaluation tools for informed decision-making. Such tools, unlike the rating systems, ideally need to handle uncertain data, incorporate expert opinion and adapt to project and geographic specific constraints. Deterministic approaches for life cycle cost analysis (LCCA) and life cycle assessment (LCA) have been extensively applied to select sustainable pavement alternatives. However, the information used to conduct LCCA and LCA is often imprecise and vague in early project phases. Therefore, certain technique is required to incorporate and propagate such uncertainties so that the reliability of final results is transparent. Unlike probabilistic methods, fuzzy based techniques are more appropriate to handle uncertainties due to vagueness and imprecision in a computationally efficient manner. This study aimed to investigate the use of fuzzy logic to evaluate sustainability under uncertainty at two levels of infrastructures - Roadways as systems and pavements as components. A novel roadway sustainability evaluation framework was developed using indicators from existing green rating system. A customizable excel-based tool was programmed based on the framework to estimate the sustainability index (SI) of roadways under uncertainty using fuzzy synthetic evaluation (FSE) technique. The FSE technique enables the tool to evaluate reliable and informative SI by incorporating expert opinion. Moreover, fuzzy composite programming (FCP) technique was used to estimate the life cycle environmental and economic sustainability indices (SIs) from LCA and LCCA of pavement alternatives under uncertainty. The FCP technique improved the reliability of final results by propagating input uncertainties to the outputs. Scenario analysis was performed using FSE and FCP techniques to demonstrate the influence of uncertainties and decision maker’s preferences on the overall SI of roadways and pavements respectively. This study demonstrated a compelling utility of fuzzy-based techniques to evaluate sustainability under uncertainty in the early project phases for informed decision-making.

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Attribution-NonCommercial-NoDerivs 2.5 Canada