  Previous studies have found correlations between the implementation of
transit signal priority (TSP) and the reduction in number of crashes. To
further understand how TSP affects traffic safety, a more in-depth evaluation
was carried out using detailed bus automatic vehicle location (AVL) data. The
data was from Minneapolis-Saint Paul Metro Transit Bus Route 5, where TSP was
implemented at 30 signalized intersections in early 2019. A surrogate safety
measure, bus speed volatility (BSV), was used to estimate the safety effects of
TSP, with a higher BSV indicating more safety risks. A regression analysis was
carried out on 23,123 event-level observations, with event defined as a bus
traversal of a TSP-equipped intersection. Results indicate that with a TSP
request, BSV was significantly lower than without a TSP request, confirming the
effectiveness of TSP in smoothing bus trips through intersections, thus
reducing risks of bus collisions and passenger fall-overs.
