Transit signal priority (TSP) is designed to reduce delay for transit vehicles through signalized intersections. For an existing TSP system, it is important to assess how timely and effective TSP phases are granted to buses that request priority. It is also necessary to evaluate the time savings and delays for buses and other vehicles as a result of TSP phases. However, due to the lack of disaggregated and integrated transit, traffic and signal phase data, previous studies have not investigated the TSP performance at the phase level. This study collects and integrates three archived databases: bus automatic vehicle location (AVL) and automatic passenger count (APC) data, intersection signal phase log data, and vehicle count data. Based on the integrated database, this research proposes innovative and useful performance measures to assess the timeliness and effectiveness of TSP phases to buses that request priority. This study also evaluates the time savings and delays to buses and other vehicles on major and minor streets. Results show that TSP performance varies significantly across intersections. On average, most of the TSP phases were granted timely to buses that request priority, but only a few of them were effective. Early green phases are more effective than green extension phases because too many green extension phases were granted late. For each early green phase, the total passenger time savings for buses and other vehicles on major streets is much higher than the delay to vehicles on minor streets. However, for each green extension phase, the total time savings on major streets is almost equal to the total delay on minor streets.
Wei Feng is a performance analyst at Chicago Transit Authority. He is a PSU alumnus; he graduated from the Transportation Engineering program here at PSU. His research interests include public transit service reliability, intelligent transportation systems and freight transportation. Currently, he mainly focuses on analyzing factors that affect transit service reliability and strategies to improve service reliability.
Wei Feng's seminar is sponsored by the NITC visiting scholar program.