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Pre-implementation evaluation of safety improvement programs

University of British Columbia

This thesis describes the development of an economic-based prediction and evaluation procedure that can be utilized in prioritizing safety improvement projects. The objective of the procedure is to alleviate the problems associated with traditional economic analysis of road safety improvement programs. Traditionally, the overall effectiveness of safety improvement programs is normally based on the benefits anticipated from a reduction in road collisions. Although the procedures for performing the economic analysis of road safety improvements in general are reasonably straightforward and well documented in the literature, these procedures fail to accurately estimate the safety benefits or disbenefits of these improvements on a consistent basis. The problems can be categorized into two parts: system-wide versus project-level analysis, and dealing with the uncertainties in the effectiveness and applicability of the proposed countermeasure. To resolve these problems, this thesis first describes the development of a new safety analysis software known as ISECR (the Information System for Estimating Crash Reductions) which can be used to determine the expected collision reduction due to a specific countermeasure. ISECR is an intelligent database that uses a case-based reasoning approach and consists of past safety research efforts on collision reduction factors (CRFs) associated with different countermeasures. The system can be used to determine the expected CRFs and the associated range and reliability of the proposed countermeasure when applied to a particular problem at hand. The safety benefits of implementing a countermeasure at a location can be represented by the expected reduction in collision frequency, which is normally calculated by the product of CRFs and the expected number of collisions. With the ISECR predictions on CRFs and the expected number of collisions determined by the multivariate and Empirical Bayes methods, this thesis then illustrates the use of the moment approach to evaluate the expected collision reduction and its uncertainty. The results can then be used to assist in evaluating the economic feasibility of a countermeasure prior to its implementation. Specifically, the probability of achieving a preset economic goal (i.e., a specific benefit-cost ratio) by implementing a countermeasure at a specific location can be determined. Finally, the prototype ISECR has been verified and validated using several case studies. The results of the verification and validation have shown that ISECR produced results that are comparable to the results obtained from real cases.

Thesis/Dissertation

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2009-07-06

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http://hdl.handle.net/2429/10284

Civil Engineering

University of British Columbia

UBCV

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