MDT crews installing hundreds of miles of "mumble strips" on Western MT roads

Posted at 12:57 PM, May 04, 2021
and last updated 2021-05-05 12:55:32-04

MISSOULA — If you see Montana Department of Transportation (MDT) crews cutting holes in the middle of your local highway this summer don't be perplexed.

It's all part of an effort to increase safety on our busy two-lane highways.

This season, MDT will be cutting new rumble strips down the centerline of all our major highways, from the Bitterroot to the Flathead and the Kootenai.

It's all part of an effort to keep drivers alert and cut the risk of head-on crashes.

“The data that's out there is incredible about how effective they are reducing the catastrophic head-on crashes that can take place," explained MDT Missoula District Administrator Bob Vosen.

Those have been of special concern on US Highway 93 south of Missoula, where every year a number of people lose their lives because of head-on crashes.

It's not an inexpensive modification, but far more cost-effective than trying to install concrete "jersey barriers".

And to be precise here, these aren't really "rumble strips" like we've had on the shoulder for years. There are "mumble strips", a quieter variant.

"The mumble strip is lower noise. Trying to reduce how loud it is outside the vehicle, but still provide that positive feedback to the driver so that they know that they're straying across that double yellow line.”

The strips do fill with water, and ice in the winter. But Vosen says they're already working well in winter across the rest of the state.

"The plows obviously can't remove that snow that's in the bottom of the of the rumble strip itself, but they are spaced out enough for it," Vosen notes. "It's not really creating a slippery spot in there because of the dry pavement that is in between each of the grooves.”

MTN News asked Vosen about whether the holes could cause the pavement to break up sooner.

“Yeah. Maybe slightly accelerated degradation of the roadway, but the savings of lives is much, I mean it's definitely worth it," Vosen explained. "You can't argue with the safety factor. That's what they bring to the table.”

MDT is installing those strips on some of the busier, undivided 4-lane highways, such as Highway 93 south of Missoula and US Highway 2 west of Columbia Falls.

Vosen says the low noise rumble strips not only keep down highway noise for nearby homes, but are less disruptive to wildlife.