Effective transit signal priority.

DKS Associates assisted Pierce Transit with the deployment and evaluation of transit signal priority (TSP) in six corridors in Pierce County, Washington. This paper describes the TSP strategies implemented by Pierce Transit and the resultant reduction in transit signal delay. In addition, this paper considers the tools and methodology needed for the deployment of an effective transit signal priority system. Steps to a successful TSP deployment are discussed. These steps include data collection, analysis of TSP, design considerations and implementation tools. Key aspects of the Pierce Transit design included the use of existing traffic signal controllers, design of the TSP detection zone for near side bus stops using 3M Opticom equipment and the development of a data management resource tool. Two methods of providing TSP were tested by Pierce Transit: Low Priority Preempt (LPP) and Green Extension/Red Truncation (GE/RT). The Pierce Transit program benefited both transit and general purpose traffic and resulted in a significant cost saving to the motoring public. Overall transit signal delay was reduced by 35% in the AM peak hour and 43% in the PM peak hour. Auto signal delay was reduced by 48% the AM and PM peak hours. The total project benefits were estimated at $14.2 million per year compared to a total project investment of $2.69 million.