Shoulder rectangular rumble strips reduce crashes for both two-lane undivided and four-lane divided rural roadways, according to findings of a MnDOT sponsored analysis.
In 2011, MnDOT implemented a rumble strip policy requiring new centerline and shoulder rumble strips, where sufficient shoulder is present, on rural roads with posted speed limits of 55 miles per hour or higher. This evaluation aimed to determine the safety effect of rumble strips on Minnesota roads from 2012 to 2018.
The results show that, in general, roads with rectangular rumble strips have fewer crashes in total and fewer fatal or serious injury crashes relative to comparable roadways without the treatments. Shoulder rumble strips appear to be especially effective on rural four-lane roadways, particularly for single vehicle run-off-the-road crash types. Specifically:
- Rural two-lane roads with shoulder rectangular rumble strips on average have 32 percent fewer total crashes than comparable roads without them.
- Rural four-lane divided roadways with shoulder rectangular rumble strips have, on average, 34 percent fewer total crashes. The average reduction in single vehicle run-off-the-road crashes is even higher: 60 percent.
Learn more:
- Rectangular Rumble Strip Safety Evaluation (MnDOT, Apr. 2020)