Roadway Departure | March 2021

Rumble strips graphic.
Source: FHWA

ACTION

Through the Federal Highway Adminstration’s (FHWA) Focused Approach to Safety program, the California Department of Transportation (Caltrans) developed a Roadway Departure Safety Implementation Plan (RwDSIP) in 2012. Using Caltrans’ crash data, a total of 7,198 candidate locations were identified for countermeasure deployment using a two-pronged approach. Caltrans identified crash types that specific countermeasures were designed to impact and selected clusters of locations where the targeted crashes exceeded the designated threshold, which varied for each countermeasure. Roadway characteristics and traffic volumes also were considered in candidate location selection. The approach combined low-cost engineering countermeasures followed by education and enforcement efforts and was targeted to reduce severe roadway departure crashes on corridors and within municipalities that experienced severe roadway departure crashes.

RESULT

Fast forward to 2020. One of the significant results of Caltrans implementing its RwDSIP is that it has made permanent changes to the way it does business; it has incorporated rumble strips as a standard treatment with new projects. Overall, center line and edge line rumble strips were the most applied countermeasure across the state. Several center line and shoulder rumble strip deployments were already in place/programmed prior to the RwDSIP, but the RwDSIP increased deployment. Caltrans’ existing monitoring list for cross-center line crashes has been decreasing over time, indicating that these types of crashes are trending down with a drop in overall frequency.

Not only did Caltrans see a reduction in crashes after implementing different countermeasures but it has been viewing treatments in a more systemic and proactive fashion as opposed to being reactive at isolated locations.

RESOURCES

Caltran’s Experience: additional information

Rumble Strips and Rumble Stripes: general design and construction information, how to accommodate all users, mitigating noise strategies, maintenance and policy, guidance, and other research information.