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NETWORK-LEVEL VEHICLE CRASH PREDICTIONS INCORPORATING TIME-DEPENDENT EFFECTS INTO CONSIDERATIONS
Title
NETWORK-LEVEL VEHICLE CRASH PREDICTIONS INCORPORATING TIME-DEPENDENT EFFECTS INTO CONSIDERATIONS
Creator
Dao, Hoang
Date
2016, 2016-07
Description
Maintaining highway safety is viewed as the over-arching goal of mananging transportation systems at all levels. According to the National...
Show moreMaintaining highway safety is viewed as the over-arching goal of mananging transportation systems at all levels. According to the National Highway Traffic Safety Administration (NHTSA), over 37,000 people got killed and 2.35 million are injured in road crashes annually. The equivalent economic and societal losses are on the order of over $231 billion, or an average of $820 per person. Thus, developing vehicle crash models that can accurately predict crash occurrences becomes essential. The study begins with literature review of models for predicting vehicle crash frequencies and crash severity levels on highway segments and at highway intersections. The findings of literature review indicate that some models lack prediction accuracy owing to exclusion of many crashing contributing factors. Consequently, a new methodology for improved vehicle crash predictability is proposed to include as many crash contributing factors as possible. In addition, the proposed methodology aims to conduct crash predictions targeting a highway network. Two computational experiments are performed for methodology application, including one on highway segment-related crash predictions using data on Highway Safety Information System for Illinois from 2001 to 2010, and another one on intersection-related crash predictions using crash data on more than one thousand intersections for period 2004 to 2010 provided by city of Chicago. Cross comparisons are made on the results obtained by applying the proposed methodology, method documented in Highway Safety Manual (AASHTO, 2010), and Empirical Bayesian (EB) before-after method for validation. The proposed methodology is found to have out-performed the other two methods. Future research directions are provided for continuing refinements of the proposed methodology.
Ph.D. in Civil Engineering, July 2016
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INCORPORATING SAFETY HARDWARE PERFORMANCE FUNCTIONS INTO RISK-BASED HIGHWAY SEGMENT SAFETY EVALUATION
Title
INCORPORATING SAFETY HARDWARE PERFORMANCE FUNCTIONS INTO RISK-BASED HIGHWAY SEGMENT SAFETY EVALUATION
Creator
Dao, Hoang
Date
2012-07-23, 2012-07
Description
Nowadays, State transportation agencies have developed management systems as analytical tools to improve roadway safety. Management systems...
Show moreNowadays, State transportation agencies have developed management systems as analytical tools to improve roadway safety. Management systems dealing with traffic safety hardware including traffic signs, signals, lighting, pavement markings, guardrails, barriers, and crash cushions have been identified as an important and non-separable part of safety management. As statistics shown, approximately 42,000 deaths on American roads due to vehicle crashes with one of the main causes being in lack of adequately performed safety hardware. It is easily realized that along the time the performance of traffic safety hardware decreases. State transportation agencies have spent millions of dollars on maintenance and replacement of safety hardware in each year. However, most of the agencies have not developed robust methodologies to assess impacts of traffic safety hardware on safety performance and optimize safety hardware investments. This study began with a literature review of safety performance functions and useful service lives of different types of safety hardware. Based on findings of the literature review and case studies conducted nationwide, this research proposes a new risk-based methodology for computing the safety index that assesses impacts of safety hardware conditions on vehicle crashes. The methodology is applied to a computational study by using 5- year data from 2002 to 2006 on 193 highway segments in Ozaukee County, Wisconsin. The results are compared with Empirical Bayesian adjusted crash estimates via statistical tests in order to validate the proposed methodology. Finally, it discusses future directions for continuing refinements of the proposed methodology.
M.S. in Civil Engineering, July 2012
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