All of us are familiar with the loud rumbling sound when our auto tire crosses over the outside white line on US 93. And on other sections, there's a similar rumble when you stray across the center line. The Montana Department of Transportation is planning to add more of those centerline rumble strips in western Montana, starting in Ravalli County.

The technology of the rumble strips has improved, according to Rainier Butler in a news release this week. He said the "low-noise" rumble strips will cause vibration, but the noise will not be as loud outside the vehicle, "making them less disruptive to people living along the highways."

The centerline strips are to prevent headon and sideswipe crashes by straying into oncoming traffic. Construction engineer John Schmidt said in the news release that studies in other states have shown a reduction in "roadway departure" accidents as much as 42 percent and even as much as 73 percent less severe injury crashes.

October is the month when the work will start on a major portion of US 93 in the Hamilton area and on a portion of the East Side Highway, northeast of Hamilton. He said traffic will be slowed, but not stopped, during installation. the western Montana project will continue next year.