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Lines marking the outside edge of travel lanes on Minnesota highways will become wider starting this year.
The white edge lines, sometimes referred to as fog lines, will be expanded from the minimum required 4 inches wide to 6, and going forward will be put down when the Minnesota Department of Transportation (MnDOT) carries out construction projects or repaints current lines as part of regular maintenance, said Brian Sorenson, a state traffic engineer.
In Minnesota and nationally, more motorists are killed or seriously injured in run-off-the-road crashes than in any other type of crash, according to MnDOT and the Federal Highway Administration. Wider lines are one strategy MnDOT is taking to help reduce road departure crashes and the deaths and injuries they bring, Sorenson said.
"When people don't have to focus on finding that line, they can pay attention to other things they may run across like animals or other motorists," he said.
Wider edge lines make it easier for drivers to see travel lane boundaries compared to traditional 4-inch edge lines, and they help motorists see the alignment of the road, the Federal Highway Administration (FHWA) said. Wider edge lines also are effective in reducing crashes on rural two-lane highways, especially for single-vehicle crashes, the FHWA said.
A study in the early 2010s by the Texas Transportation Institute analyzing data from Kansas, Michigan and Illinois found replacing 4-inch edge lines with 6-inch lines can reduce total crashes by 15 to 30% and fatal and serious injury crashes by as much as 38%. Other studies have shown wider edge lines have led to a 20 to 40% decrease in run-off-road crashes that lead to injury or death, Sorenson said.
Minnesota is hoping to see similar results as "the prevalence of these types of crashes is increasing," Sorenson said.
Between 2016 and 2020, there were 2,848 road departure crashes that resulted in a death or serious injury in the state, an average of about 570 a year. Last year there were 668 run-off-the-road fatal and serious injury crashes in Minnesota and they accounted for about 30% of all fatal and serious injury crashes, state data show.
More than 65% of the crashes happened in rural areas, Sorenson said.
Painting wider lines is a low cost solution compared with other safety mitigation efforts such as rumble strips and cable median barriers MnDOT has invested in over the years, Sorenson said. But it's not no cost. A 6-inch edge line costs about 25% more to put down than the typical 4-inch line. A 2017 MnDOT document states putting down a 6-inch line costs $400 per mile using latex paint and $1,300 per mile using longer-lasting epoxy. But with supply issues and inflation raging, costs will likely be much higher, Sorenson said.
Besides safety, another reason to install wider lines is the growing number of vehicles equipped with lane line detection technology.
"Wider lines will help those systems work better," Sorenson said.
