Effectiveness of sealed shoulders and audible edge lines in Western Australia

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.