Rumble strips are grooves in the pavement that produce a rumbling noise and vibration when a vehicle drives over the strip. Shoulder rumble strips have been utilized on Montana's highways for decades to alert drivers veering off the side of the road. Rumble strips, installed along the centerline of two-way highways, are the newest addition to Montana's rumble strip safety implementation. Centerline rumble strips are a key measure in Montana Department of Transportation's Vision Zero initiative to reach zero deaths and zero serious injuries on Montana's roads.
MDT conducted a five-year statewide installation of centerline rumble strips designed to prevent roadway departure crashes, particularly head-on and sideswipe crashes that occur when a vehicle crosses the centerline of a two-lane highway into the oncoming lane of traffic.
Montana drivers should be aware of the following when driving on two-lane highways installed with centerline rumble strips:
MDT is dedicated to making the state's roadways safe for all those that use them for transportation and recreation. As with cars and trucks, rumble strips are effective in keeping motorcyclists alert and in their lanes.
In MDT's design of rumble strip installations, they have consulted with bicycle advocate groups, such as Bike Walk Montana, to design a rumble strip width that leaves plenty of space for bicyclists. The width of the centerline rumble strip is modified based on the size of the road's shoulder. Rumble strips are six inches wide on a highway with no shoulder, eight inches wide on highways with a two-foot shoulder, and 12 inches wide with a four-foot or wider shoulder. A modified shoulder rumble strip is also installed on bicyclist-designated highways / routes that have a shoulder width of less than four feet. To accommodate bicyclists as well, shoulder rumble strips have a 13-foot gap every 47 feet.
MDT is targeting specific stretches of highway for the centerline rumble strip implementation. Installation occurred on two-lane highways that meet these criteria:
The current rumble strip policy was established in 2015 by MDT’s Chief Engineer in response to nationwide research indicating that the number of roadway departure crashes significantly decreased using rumble strips. Roadway departure crashes (run-off-the-road, head-on, and opposite direction sideswipe crashes) are documented as the highest percentage of crash type for Montana’s highways, so installing rumble strips can help significantly reduce fatal and serious injury crashes on Montana highways.
Funding for the installation of rumble strips comes from several federally funded programs, depending on the highway project in question. The recent statewide initiative to install centerline rumble strips (CLRS) was funded by Highway Safety Improvement Program (HSIP) funds since CLRS are recognized as a nationally proven safety countermeasure [safety.fhwa.dot.gov]. MDT analyzed routes with a history of roadway departure crashes to select routes as discussed above.
Yes, Montana citizens have and will continue to be encouraged to give feedback per MCA 60-2-245. MDT is committed to engaging and informing the public through our website, newspaper, tv, and radio, as well as electronic and social media. Interested parties can find examples on our website here and several news releases and interviews, an example of which is here [charkoosta.com].