Potential crash reduction benefits of shoulder rumble strips in two-lane rural highways.

This paper reports the findings from a study aimed at examining the effectiveness of shoulder rumble strips in reducing run-off-the-road (ROR) crashes on two-lane rural highways using the empirical Bayes (EB) before-and-after analysis method. Specifically, the study analyzed the effects of traffic volume, roadway geometry and paved right shoulder width on the effectiveness of shoulder rumble strips. The results of this study demonstrate the safety benefits of shoulder rumble strips in reducing the ROR crashes on two-lane rural highways using the state of Idaho 2001-2009 crash data. This study revealed a 14% reduction in all ROR crashes after the installation of shoulder rumble strips on 178.63miles of two-lane rural highways in Idaho. The results indicate that shoulder rumble strips were most effective on roads with relatively moderate curvature and right paved shoulder width of 3 feet and more.