Effectiveness of Sealed Shoulders and Audible Edge Lines in Western Australia

Abstract

Objective: Sealing of road shoulders and installation of audible edge lines (also known as rumble strips or audio tactile profiled edges) are common engineering road treatments, often implemented to prevent run-off-road crashes. This quasi-experimental study evaluated the effectiveness of installing sealed shoulders and/or audible edge lines on the Albany Highway in Western Australia during 2000–2004 relative to matched control sites.

Methods: Reduction in crash frequency post-2004 and the economic benefits of applying these treatments to 13 sites were assessed.

Results: The treatments were highly effective overall, significantly reducing all-severity crash rate by 58 percent and casualty crashes by 80 percent. The reduction in crash cost was estimated to be $51.9 million Australian dollars over the lifetime of the treated sites, with $51.4 million attributable to the decrease in casualty crashes. After accounting for treatment costs, the net cost savings to the community were estimated at $50.6 million. The benefit–cost ratio across all treatment sites was 40.3.

Conclusions: The findings justified the implementation of these treatments on rural roads in terms of benefits for reduction in both crash rate and crash cost.

Keywords:

• Audible edge lines
• Cost-effectiveness
• Crash reduction
• Rumble strips
• Sealed shoulders

ACKNOWLEDGMENTS

This research was funded by Main Roads Western Australia. The authors acknowledge the contributions from Maurice Cammack, Jana Geisler, Chris Ilias, Geoff Murray, Sanath Jayamanna, and Michelle Fraser. The authors are also indebted to Tony Radalj and Syeda Sultana for their time, support, and feedback on various aspects of data management.