With a goal of reducing collisions, WSDOT implemented policy for installing centerline rumble strips on undivided highways and invested in funding strategies for those installations in 2006. There have been some limited studies on the effectiveness of those installations, but a more complete study is appropriate.
Most of the previous analysis has been focused on the types of collisions that rumble strips were intended to reduce: specifically, centerline crossovers. Other collision types, such as run-off-the-road-to-the-right, have not been adequately explored previously to determine whether their frequencies have changed. The effectiveness of rumble strips on targeted collision types also needs to be reviewed to determine whether there are any site characteristics that influence effectiveness.
This study evaluates the effectiveness of centerline rumble strips under a variety of traffic and geometric conditions. The findings will result in better guidance on when to use rumble strips to address various collision types.