Evaluation of Transit Signal Priority Using Observed and Simulated Data

Document Type

Journal Article

Publication Date


Subject Area

operations - traffic, infrastructure - bus/tram priority, infrastructure - bus/tram priority, infrastructure - traffic signals, economics - appraisal/evaluation, mode - bus


Transit buses, Traffic simulation, Traffic signal priority systems, Traffic signal preemption, Snohomish County (Washington), Preemption (Traffic signals), Level of service, Field studies, Evaluation, Bus priority


The South Snohomish Regional Transit System Priority (SS-RTSP) system was launched in Washington state to improve the level of service for community transit buses. This study uses field data and simulation models to quantitatively evaluate the impacts of the SS-RTSP system on both transit and local traffic operations. The evaluation results show that the SS-RTSP system produces substantial benefits to transit vehicles with insignificant negative impacts to local traffic on cross streets. Transit vehicles operated more reliably with the SS-RTSP system. Because of reduced travel time, the SS-RTSP system decreased the overall person delays as well.