Abstract

Every year hundreds of night time road collisions result in fatalities and injuries in Canada. Roadway lighting is considered as the main countermeasure to prevent nighttime crashes. Provision of lighting follows two industry standards in North America: one for the warrants and the other for minimum recommended levels. The warrant system assigns scores to highway segments based on geometrical, operational and functional characteristics as well as the collision history through a night-to-day crash-ratio. Transportation agencies in North America had manifested their interest in simplifying the warrant system; eliminating elements and/or modifying lighting values, however, there is a need for a method to support lighting decisions over its effectiveness as a countermeasure. This thesis presents a novel method to calibrate lighting warrants and to identify effective levels of lighting in order to reduce the severity and frequency of night-time collisions. This new method uses an evidence-based mechanism to connect lighting warrants with statistical analysis of collisions in order to adjust the scores of the warrant. It also connects the estimation of lighting levels with evidence-based statistical analysis of crash-history in order to identify recommended levels of luminance, illuminance and uniformity variations. The method expands the industry standards by providing the decision maker with two alternate non-exclusive approaches supported over collisions’ frequency and severity criteria. A large-scale case study for highways in Quebec was used to calibrate the warrants and identified recommended levels of luminance of at least 1.5cd/m2, maximum uniformities of illuminance of 1.5 and of luminance of 8 times to prevent severe and frequent collisions. A case study of Arthabaska region in Quebec found that levels of luminance should be increased for every functional classification of roads that values of uniformity must be reduced, and that levels of illuminance increased to reduce severe collisions. The novel methods developed in this research will provide province/state transportation agencies and municipalities with the capability of not only allocating lighting when is needed and justified, but also of selecting the optimal levels that result in effective reductions in nighttime road collision frequency and severity, signifying safer roads for the society at large.