The traffic safety issue especially in urban areas is getting increasingly severe due to the ever-growing travel demand which closely related... Show moreThe traffic safety issue especially in urban areas is getting increasingly severe due to the ever-growing travel demand which closely related to people’s basic necessities. As a part of the urban traffic network, the safety of the intersections in the urban area also reflects the efficiency and quality of the integrated urbanization level. Red light running at intersections has been a major safety concern in the United States. Because the red light running at intersection often results in a disproportionally higher percentage of injuries. From this point of view, the safety improvement of the urban intersections is imperative. The red light running photo enforcement has been designed to increase safety on streets by reducing the head-on, rear-end, and sideswipe crashes at intersections. Meanwhile, methods for intersection signal timing optimization in urban areas have been developed to reduce intersection delays. As a result of delay reductions, it is also important to analyze changes in vehicle crashes in order to gain a holistic understanding of traffic mobility and safety impacts. This study introduces an Empirical Bayesian (EB) before and after analysis method to evaluate the safety impacts of signal timing optimization on urban intersections with some intersections involved with red light running photo enforcement. Data on 842 signalized intersections are collected to calibrate the safety performance functions and to quantify the crash reduction effects before and after the signal timing optimization. Base on the EB method application, it is reviewed that a certain extent of safety enhancements is achieved as measured by crash type and severity level after intersection signal timing optimization and red light photo enforcement treatments. M.S. in Civil Engineering, December 2015 Show less
