Safety Evaluation of Red-Light Cameras and Dynamic Speed Display Signs Within the City of Ottawa

Abstract

This thesis evaluates the safety impacts of red-light cameras (RLCs) and Dynamic Speed Display Signs (DSDSs) in Ottawa, Canada. The study examines the safety impacts of RLCs on safety performance, using collision records, and driver behaviour using surrogate safety measures. The safety impacts of DSDSs on driver behaviour are evaluated using speed analysis. An empirical Bayes method for RLCs showed a significant impact, where total and PDO collisions increased while injury and fatal collisions decreased. The impact of RLCs also depended on the collision types, where sideswipe, rear-end, and SMV collisions increased, but the angle and turning collisions decreased. The increase in rear-end collisions was also examined through an analysis of traffic conflicts. The results indicated that treated sites had significantly more severe rear-end conflicts that had likely resulted from harder deceleration rates. Speed analysis for DSDSs indicated drivers reduced their speed when they saw their actual speed on DSDSs.