Evaluation of GPS-Based Transit Signal Priority for Mixed-Traffic Bus Rapid Transit

GPS-based transit signal priority (TSP) is a new type of transit preferential tool being considered in many North American cities. With GPS detection and advanced communications, GPS-based TSP provides flexible and conditional signal priority to transit vehicles. This is a relatively new system with limited field implementations and evaluations. The research in this study used microscopic simulation, to create a set of TSP scenarios for a 3-mi bus corridor and evaluated the influences of GPS-based TSP on transit and traffic operations. The simulation network was the 3300 South corridor, including side streets, in Salt Lake County, Utah. A proposal was evaluated to upgrade the Utah Transit Authority Bus Route 33 operating along the corridor into a bus rapid transit (BRT) line running in mixed traffic. Eight simulation scenarios were created to cover (a) current field conditions, (b) regular bus with traditional TSP implementation, (c) regular bus with GPS-based TSP, (d) BRT implementation with no TSP, (e) BRT with traditional TSP implementation, (f) BRT with GPS-based TSP, (g) BRT with conditional TSP, and (h) BRT with multiconditional TSP implementation. The evaluation included transit and nontransit operations, and the impacts on side-street traffic. The results show that GPS-based TSP performed as effectively as did traditional TSP. Conditional and multi-conditional TSP strategies showed benefits in providing the transit system considerable delay reduction (13% and 3%, respectively) and travel time savings (7% and 3%, respectively) while having the smallest impacts on side-street traffic (3% and 1% increase in delay, respectively) compared with other TSP strategies.