An empirical bayes safety evaluation of tram/streetcar signal and lane priority measures in Melbourne

ABSTRACT

Objective: 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.

Method: A before–after crash study was conducted using the empirical Bayes (EB) method to provide more accurate crash impact estimates by accounting for wider crash trends and regression to the mean effects. 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.

Results: The EB before–after analysis results indicated a statistically significant adjusted crash reduction rate of 16.4% after implementation of tram priority measures. Signal priority measures were found to reduce crashes by 13.9% and lane priority by 19.4%. A disaggregate level simple before–after analysis indicated reductions in total and serious crashes as well as vehicle-, pedestrian-, and motorcycle-involved crashes. In addition, reductions in on-path crashes, pedestrian-involved crashes, and collisions among vehicles moving in the same and opposite directions and all other specific crash types were found after tram priority implementation.

Conclusions: Results suggest that streetcar/tram priority measures result in safety benefits for all road users, including vehicles, pedestrians, and cyclists. Policy implications and areas for future research are discussed.

KEYWORDS:

• road safety
• tram priority
• streetcar priority
• empirical Bayes method
• before–after study
• crashes

Acknowledgment

The authors thank Yarra Trams and VicRoads for providing information related to tram priority measures implemented in Melbourne.

Notes

¹ Australian Research Council Industry Linkage Program project LP100100159, “Optimizing the Design and Implementation of Public Transport Priority Initiatives,” Institute of Transport Studies, Monash University in association with the Transport Research Group, University of Southampton, UK. The principal chief investigator is Professor Graham Currie, the chief investigator is Associate Professor Majid Sarvi, and the partner investigator is Dr. Nick Hounsell. Farhana Naznin is one of the 2 APA (I) PhD students on the project. The industry sponsors include VicRoads and Public Transport Victoria.

Additional information

Funding

The authors thank the Australian Research Council for financial support of this research.