Study finds rumble strips significantly cut crashes on Michigan highways

The Michigan Department of Transportation (MDOT) said Monday that a Wayne State University (WSU) study found that rumble strips on state highways significantly reduces head-on, sideswipe and run-off-the-road crashes.

MDOT started a major rumble strip program in 2008, when centerline and shoulder rumble strips were installed on all rural, nonfreeway highways with posted speed limits of 55 mph and appropriate paved lane and shoulder widths. To date, MDOT has placed 5,700 miles of centerline rumble strips and 1,700 miles of shoulder rumble strips.

WSU Civil Engineering Professor and Principal Research Project Investigator Tapan Datta said the study is one of the largest and most comprehensive investigations of effectiveness of any safety countermeasure that has ever been performed at a state level.

"Analyzing all of MDOT's two-lane high-speed highways with rumble strip treatments targeted to alleviate lane departure-related traffic crashes makes the results real and reliable,” Datta said. “They can be used by other states to establish their own rumble strip programs."

Datta said future research should focus on use of rumble strips on two-lane county roads and multilane nonfreeway high speed roads.

''Rumble strips are a proven and cost-effective countermeasure to lane departure crashes brought on by driver drowsiness, distraction, and/or inattention,'' the report said. ''We can project … this initiative in Michigan will result in an annual reduction of 337 crashes, saving 16 lives, and 62 serious injuries each year.''

The safety gains showed a high benefit-to-cost ratio. Depending on how the cost was spread out over time, the ratio was between 58:1 and 18:1. Researchers estimated a total safety benefit of more than $79 million over three years.

The survey also indicated strong public support for the use of centerline rumble strips.