Analysis of Transit Signal Priority Using Archived TriMet Bus Dispatch System Data

This paper presents findings on changes in bus running times, on-time performance, and excess passenger wait times following implementation of transit signal priority in select bus corridors in the Portland metropolitan region. Analysis of the effectiveness of transit signal priority is often undertaken using simulation techniques or empirical studies that are either limited in scope and/or data availability. The present research uses an abundance of trip-level data collected from TriMet’s Bus Dispatch System. The study focuses on the most common performance measures of interest to both transit operators and passengers. Our study shows that the expected benefits of TSP are not consistent across routes and time periods, nor are they consistent across the various performance measures. We believe that benefits of transit signal priority will accrue only as the result of extensive evaluation and adjustment initial deployment. In most cases, an ongoing performance monitoring and adjustment program should be implemented in order to maximize the benefits of transit signal priority.