DOT truck treating the interstate.

DOT truck treating the interstate.

Testing is underway on a project in central Iowa that could reduce the number of traffic crashes during snow storms. Iowa Department of Transportation engineer Willy Sorenson says the idea involves the use of sensors and lasers to monitor winter pavement conditions.

A mathematic formula then calculates an “advised” slower speed limit which is posted on digital signs along Interstate 35.

On an icy day, for example, the signs might suggest a speed limit of 55 miles-an-hour. “In theory, with that, you should be able to reduce crashes and when you reduce crashes, you reduce fatalities,” Sorenson says. Many crashes on the interstate during a snow storm happen because some motorists are driving too slow at a time when others are going too fast for the conditions.

Sorenson believes an “advisory speed” would bring the speeds of all vehicles closer together and make it safer on the interstate. In addition to the advised speed limit, the digital signs carry a message explaining why motorists should slow down. “We hope that ‘why factor’ will help people with the compliance to that advised number,” Sorenson says. The project involves four digital signs along an 11-mile stretch of I-35 between Ankeny and Huxley. The area was chosen because it’s one of the most dangerous stretches of interstate in Iowa, especially in the winter.

Sorenson hopes to expand the project next year. “We’re going to try and get one phase done this winter and the real big push is for next winter,” Sorenson says. There were 319 traffic fatalities in Iowa last year and 35 were blamed, at least in part, on snowy or icy road conditions — according to the Iowa DOT.