Sun Glare: Network Characterization and Safety Effects

Abstract

This research conducted a two-stage assessment to investigate sun glare effects on road safety in Edmonton. The first stage developed a methodology to model sun glare occurrence, aiming to identify when and where drivers are most likely to be exposed to sun glare. Safety risks at those identified locations during sun glare periods were assessed in the second stage. By contrasting the collisions during glare and non-glare conditions, this second stage aimed to quantify the effects of sun glare on road collisions. Consequently, three major findings were concluded. First, sun glare was found to significantly contribute to collision occurrence, especially at road intersections. Second, the effects of sun glare on collision occurrence during mornings on the eastbound and evenings on the westbound were observed to be particularly worse in the spring and fall months. In fact, safety in the southbound direction was significantly affected by sun glare during most daytime hours in the main winter months (November, December, and January). Lastly, the analysis revealed that certain collision types were more likely to occur during periods of sun glare. For example, collisions due to signal violations and failing to yield to pedestrians/cyclist were more likely to occur at intersections. At mid-block locations, the proportion of collisions occurring due to improper turning and lane changes were observed to be significantly higher. Overall, the approach proposed in this research provides a holistic method to quantify the effects of sun glare on road collisions and offers additional insights into the extent by which sun glare affects road safety.