On average, there have been 14 fatal head-on and sideswipe motor vehicle crashes each year for the past five years on central Minnesota’s heavily traveled two-lane highways. In fact, much of the congestion and many of the crashes occur on these heavily traveled two-lane roadways. More than 30 percent of the state highway system’s two-lane rural roads, which carry more than 5,000 cars per day, are located within the Minnesota Department of Transportation (Mn/DOT) District 3, which encompasses 13 counties in central Minnesota. This trend prompted the District 3 staff to aggressively look at projects and engineering techniques that would put the brakes on the disturbing annual number for fatal crashes. In the past three years, Mn/DOT has delivered a number of highway expansion and reconstruction projects to enhance safety. During this timeframe, the new four-lane highways such as Highway 23 west of St. Cloud have reduced the number of crashes. While this is a step in the right direction, Mn/DOT must continue to look at low-cost safety enhancements to save lives. In 2000, Mn/DOT installed centerline rumble strips on nearly 50 miles of Highway 23 in Stearns and Kandiyohi counties in an effort to improve safety. The noise and vibration of rumble strips are designed to alert drivers driving too close to the opposite travel lane or who cross over the centerline into the opposing lane of traffic. Rumble strips are aimed at reducing head-on and sideswipe crashes on high-traffic volume two-lane roadways such as Highway 23. Preliminary results are favorable including market research, which found that drivers believed the rumble strips did improve safety by making them more aware of their location within the driving lane. Those results, coupled by similar findings in states such as Colorado, Delaware, Oregon, Pennsylvania and Washington, are encouraging. That’s why Mn/DOT recently installed centerline rumble strips on an additional 190 miles of rural two-lane highways throughout central Minnesota. A recent study released by the Insurance Institute for Highway Safety states that, overall, motor vehicle crashes at treated sites were reduced 14 percent; injury crashes were reduced by an estimated 15 percent. Head-on and opposing-direction sideswipe crashes – the primary target of centerline rumble strips – were reduced by an estimated 21 percent, while head-on and opposing-direction sideswipe crashes involving injuries were reduced by an estimated 25 percent. Certainly, there are concerns about increased noise for people living adjacent to the roadways where rumble strips have been cut into the pavement and concerns by crews charged with maintaining the roadway. The concerns warrant further study. These issues and more will be researched in the next three years as part of a comprehensive research effort to further refine this engineering tool to save lives by reducing crashes and injuries. It is unfortunate that such a technique has a negative effect of increased noise to adjacent residents. In our opinion, it would be irresponsible not to take action which would make our highways safer. It is hoped that vehicle crash avoidance systems will soon make the centerline rumble strip a relic of the past.
