Washington, United States
Comprehensive Evaluation on Transit Signal Priority System Impacts Using Field Observed Traffic Data
Summary Information
Transit signal priority (TSP) is an operational strategy that facilitates the movements of in-service transit vehicles through signalized intersections. Since delays incurred by transit vehicles at signalized intersections typically account for 10 to 20 percent of transit vehicle running times, TSP promotes transit utilization through improving service reliability. By reducing the waiting time of transit vehicles at intersections, TSP can reduce transit delay and travel time, thereby increasing the quality of service. The South Snohomish Regional Transit Signal Priority (SS-RTSP) project was implemented at 17 intersections over two phases, and evaluation study was performed and the report was completed in June, 2007. The study quantitatively evaluated impacts of the system on both transit and local traffic operations based on a large amount of field observed traffic data and real-world traffic control settings.
RESULTS
Evaluation results showed:
- the SS-RTSP system reduced transit corridor travel time by approximately 4.9 percent.
- decreased delay by approximately 336,766 person-hours per year for peak-hour travel.
- insignificant negative impacts to local traffic on cross streets.
- the overall person-delay saved by the SS-RTSP system was significant.