Impacts of Transit Priority on Signal Coordination

This study introduces the current application of transit signal priority (TSP) in the City of Toronto, Ontario, Canada, and focuses on the following: traffic signal operations, constraints of the current signal control system and TSP technology, evaluation metrics, and models for simulating transit priority operation. In Toronto, 335 traffic signals have transit priority, 321 of which are under the control of the main traffic signal system (MTSS). Active transit priority unconditionally allows an extension of up to 30 s per cycle in addition to the normal signal green time on transit routes. The extension generates complaints about traffic delays for vehicles on side streets, long pedestrian wait times, and poor signal coordination. Field tests were conducted on a section of a downtown Toronto arterial bus route. Actual MTSS logs and signpost data obtained by the transit agency during field tests were used to investigate three scenarios along Bathurst Street at six signalized intersections. An analysis of signal timing changes that encompassed selection and determination of traffic operation performance measures was conducted on a per-cycle basis in the morning peak, afternoon peak, and off-peak periods. Green-band effectiveness was one of the evaluation measures used to assess signal progression. Subsequently, a performance assessment frame based on a model for the analytic hierarchy process was built to determine the best scenario and to help develop simulation models. The analysis shows that the TSP strategy of unconditional extension up to 30 s in signal green time is not recommended for use with the existing system of traffic signal control. The approaches described can apply to different transit routes with variable situations in Toronto