Safety Effects of Transit Signal Priority: Magnitude and Mechanism

Transit signal priority (TSP) has been implemented for transit systems in many cities of the United States. In evaluating TSP systems, more attention has been given to its operational effects than to its safety effects. Existing studies assessing TSP’s safety effects reported mixed results, indicating that the safety effects of TSP vary in different contexts. Prior studies in the United States evaluating TSP implementations in two metropolitan areas reported reductions in overall crashes on TSP corridors after TSP activation. However, the most recent study results indicate that there is potential increase in pedestrian and bike-involved crashes associated with TSP implementations. This proposed project will be led by the research team from the Traffic Operations and Safety (TOPS) Laboratory at the University of Wisconsin-Madison, in collaboration with Metro Transit, the Minneapolis-Saint Paul metropolitan area transit agency, to evaluate the safety effects of Metro Transit Bus Route 5 TSP implementations which will be activated in December 2018. TSP, transit operations/incidents, roadway, and crash data will be gathered from Metro Transit and Minnesota Department of Transportation. Before-after analyses will be conducted to evaluate the TSP implementation’s effects on transit in-vehicle safety and road traffic safety. Statistical models will be developed to investigate the mechanisms of TSP’s safety effects. The research findings will help researchers and practitioners better understand both the magnitude and mechanism of TSP’s safety effects, and will provide support in transit agencies’ decision-making process regarding future implementations of TSP or similar technologies.