Signals, tracks, and trams: public transport signal priority impact on job accessibility over time

Improving travel time by public transport is a major task for city planners and policy makers to increase its competitiveness relative to cars which can be facilitated by implementing public transport preferential infrastructure treatments such as signal priority. We study the impact of one such preferential treatment, signal priority, on accessibility to jobs between 2015 and 2022 in Warsaw, Poland, which implemented signal priority on 187 intersections during this time period. We develop a method to extract inter-stop travel times from the General Transit Feed Service. We find that signal priority implementation lead to (1) a travel time decrease over the network by 6.7%, (2) an increase in accessibility by 5-8.5%, (3) a full signal priority setting drives the accessibility change over time, and (4) the location of SP and travel time segments at the entry point to high-density jobs drives accessibility change. Our analysis provides a method to help decision makers evaluate the impact of signal priority on accessibility to jobs. Our results indicate significant effectiveness of signal priority implementation.