Assessment of safety effects for widening urban roadways in developing crash modification functions using nonlinearizing link functions |
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Authors: | Juneyoung Park Mohamed Abdel-Aty Jung-Han Wang Chris Lee |
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Affiliation: | 1. Department of Civil, Environmental and Construction Engineering, University of Central Florida, Orlando, FL 32816-2450, USA;2. Department of Civil and Environmental Engineering, University of Windsor, Windsor, ON N9B 3P4, Canada |
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Abstract: | Since a crash modification factor (CMF) represents the overall safety performance of specific treatments in a single fixed value, there is a need to explore the variation of CMFs with different roadway characteristics among treated sites over time. Therefore, in this study, we (1) evaluate the safety performance of a sample of urban four-lane roadway segments that have been widened with one through lane in each direction and (2) determine the relationship between the safety effects and different roadway characteristics over time. Observational before–after analysis with the empirical Bayes (EB) method was assessed in this study to evaluate the safety effects of widening urban four-lane roadways to six-lanes. Moreover, the nonlinearizing link functions were utilized to achieve better performance of crash modification functions (CMFunctions). The CMFunctions were developed using a Bayesian regression method including the estimated nonlinearizing link function to incorporate the changes in safety effects of the treatment over time. Data was collected for urban arterials in Florida, and the Florida-specific full SPFs were developed and used for EB estimation. |
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Keywords: | Safety effectiveness Crash modification factors and functions Bayesian regression Nonlinearinzing link function Observational before&ndash after methods Time changes |
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