Safety issue
Roadway or lane departure crashes occur when a vehicle crosses an edge line or centerline of a roadway. These crashes account for approximately 50 percent of fatal crashes each year on the nation's highways. In Wisconsin, lane departure crashes account for over one-third of all fatal and injury crashes each year, with 90% taking place on rural Wisconsin highways.
Safety design
Rumble strips are a proven, low-cost, safety engineering countermeasure that target lane departure and inattentive driving crashes. Rumble strips are designed to alert drivers of a lane departure when a vehicle’s tire makes contact with the rumble strip which causes vibration and noise. WisDOT installs several different types of rumble strips:
- Centerline - Centerline rumble strips are placed on a roadway centerline between opposing travel lanes and provide an audible and tactile barrier between travel lanes to alert inattentive drivers who unintentionally cross the centerline. Due to the low cost and high safety benefit, WisDOT has implemented a systemic approach for installing centerline rumble strips on all rural, two-lane roadways with higher speeds since 2013.
- Shoulder – Shoulder rumble strips are placed on paved shoulders outside of the painted edge line of a roadway and alert inattentive drivers that are leaving the roadway. WisDOT installs these on all freeways and rural, two-lane highways with paved shoulders 5 feet or greater.
- Edge Line – Edge Line rumble strips are a variation of shoulder rumble strips, where the rumble strip is placed on the painted edge line. These are used on narrower paved shoulders.
- Transverse – Transverse rumble strips are placed across a travel lane to alert a driver of an upcoming condition that may not be anticipated, such as an intersection.
Benefits
Rumble strips are low-cost, relatively quick to install and are highly effective at alerting drivers and preventing roadway or lane departure crashes. Centerline and shoulder rumble strips on rural, two-lane roadways are especially helpful during poor weather conditions such as rain, snow, or fog when visibility of the edge line or centerline is reduced. Rumble strip effectiveness is estimated as follows:
- Rural Two-Lane Highways - Centerline rumble strips have shown to reduce fatal and injury crashes by 31%
- Rural Two-Lane Highways - Shoulder rumble strips have shown to reduce fatal and injury crashes by 8%
- Rural Multilane Highways - Shoulder rumble strips have shown to reduce fatal and injury crashes by 36%
- Urban Freeways - Shoulder rumble strips have shown to reduce fatal and injury crashes by 16%
- Rural Intersections - Transverse rumble strips have shown to reduce fatal and injury crashes by 21%
Additional Resources