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 actual collision records, and driver behaviour using surrogate safety measures. The safety impacts of DSDSs on driver behaviour are evaluated using safety measures of speed. Direct regression analysis of collision data on treated intersections showed a significant impact for RLCs on angle, injury, and fatal collisions but no significant impact on other impact types and severity levels, a finding that was likely affected by the relatively small number of treated sites. On the other hand, 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 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.iii AcknowledgementsFirst and foremost, I would like to state my profound appreciation to my supervisor Professor Yasser Hassan for his continuous encouragement, support and help. He gave me the precious opportunity to work on this project, and under his kind teaching and advice, I was able to find my real interest in transportation engineering. A special thanks to my co-supervisor, Doctor Ali Kassim, for his help and guidance through the project.The completion of this thesis would not have been possible without the assistance of Doctor Ali Kassim, who kindly provided data from the City of Ottawa. My sincere thanks and appreciation to both of them for being part of this journey and for constantly assisting me. Sincere gratitude to my husband and co-worker Milad Abolhassani (Master's student at Carleton university) for helping me during the video data collection process. This study was financially supported by Transport Canada's Enhanced Road Safety Transfer Payment Program (ERSTPP) and was performed in collaboration with the Traffic Department of the City of Ottawa. I would like to thank the Traffic Department of the City of Ottawa for providing this opportunity as well as authorizing permission for collecting the video data.Finally, I would like to thank my mother, Fatemeh Saeedi, and my father, Professor Mahmoud Saffarzadeh, who always wanted this journey for me and for their continuous and unending love, and support throughout my study.