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

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