Study Details

Study Title: Road Safety Impacts of Tram/Streetcar Priority Measures - A Before-After Study Using Empirical Bayes Method

Authors: Naznin et al.

Publication Date: JAN, 2015

Abstract: Streetcars/tram systems are growing worldwide and many are given priority to increase speed and reliability performance in mixed traffic conditions. Research related to the road safety impact of tram priority is limited. This study explores the road safety impacts of tram priority measures including lane and intersection/signal priority measures. Before-after crash data for 29 intersections with tram signal priority and 23 arterials with tram lane priority in Melbourne, Australia were analyzed to evaluate the road safety impact of tram priority. A before-after crash study was conducted with results adjusted using the Empirical Bayes (EB) method to allow for wider crash trend and regression to mean effects. The simple before-after results indicate that accident rates decreased from 138 to 113 per annum (-18%). Fatal and serious crashes dropped from 47 per annum to 34 per annum (-28%). Using the EB method, a statistically significant adjusted crash reduction rate of 16.4% was established. Signal priority measures were found to reduce crashes by 13.9% and lane priority by 19.4%. The disaggregate level analysis also indicated reductions in specific crash types. Results suggest that streetcar/tram priority measures result in significant safety benefits for all road users, including pedestrians. Policy implications and areas for future research are discussed.

Study Citation: Naznin, F., G. Currie, M, Sarvi, and D. Logan. "Road Safety Impacts of Tram/Streetcar Priority Measures - A Before-After Study Using Empirical Bayes Method". Presented at the 94th Annual Meeting of the Transportation Research Board, Paper No. 15-0594, Washington, D.C., (2015).

Comments: The Clearinghouse includes only the CMFs produced from the empirical Bayes analysis, given that it is the most reliable method.


CMFs Associated With This Study

Category: Transit

Countermeasure: Implement transit lane priority (at transit-serviced locations)

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.806 19.4 4 Stars All All Not specified

Countermeasure: Implement transit signal and lane priority (at transit-serviced locations)

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.836 16.4 4 Stars All All Not specified

Countermeasure: Install transit signal priority (TSP) technology (at transit-serviced locations)

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.861 13.9 4 Stars All All Not specified