MnDOT Tackles the Job

To help you better understand—and appreciate—how our roads are cleared this winter, we’re sharing facts and information about road-clearing methods and snowplows, courtesy of the Minnesota Department of Transportation.

MnDOT By The Numbers

MnDOT plows 30,517 miles of Minnesota’s state highways and interstates, including more than 4,000 lane miles in the Twin Cities metro, and employs more than 1,800 full-time and part-time snowplow drivers. These drivers are required to have a Class B commercial driver’s license, and new operators are required to take an extensive two-week training course at Camp Ripley in Little Falls. MnDOT has 843 snowplows, each of which can weigh as much as 15 times more than an average car when fully equipped.

Keeping Our Roads Clear

MnDOT primarily uses two materials to inhibit ice formation and improve roadway safety: salt and sand. Salt is effective for melting snow and ice on roads when road-surface temperatures are below freezing. The drawback of using salt is that it loses its effectiveness as temperatures drop. Sand is used to increase traction on slippery roads and is mostly used at intersections and ramps. Sand is also used during extreme cold temperatures when salt is less effective.

The following techniques help MnDOT be more efficient and use less salt and sand, which reduces our impact on the environment.

• Anti-icing—This is the process of applying liquid salt brine to the road surface just before or early in a snowfall event. This prevents precipitation from bonding to the road surface.
• Pre-wetting—This treatment involves applying liquid salt brine or other commercial chemical solutions to the rock salt or sand mixture. Pre-wetting the salt allows it to activate more quickly and causes it to stick to the road surface instead of blowing off to the shoulder and ditch.
• Deicing—This uses chemical or mechanical means to break the bond that has formed between the ice and road surface.

Snow removal performance can vary depending on the moisture content of the snow, weather conditions and the timing of the snowfall. Heavy, wet snow followed by a cold snap will require more time to clear than dry snow.

Winter Driving Safety

Winter driving in Minnesota can be dangerous, especially when snowplows are on the roads. Remember plows travel much slower than posted speeds because it is most effective for clearing roads. Also, the plow driver’s field of vision behind the truck is severely restricted, and the driver must rely on mirrors to see to the rear and side of the truck.

When driving near snowplows, consider the following:

• Stay back at least 10 car lengths between your vehicle and a plow.
• Be patient, and remember snowplows are working to improve road conditions for your trip.
• Stay alert—snowplows turn or exit frequently, often with little warning. They also may travel over centerlines or partially impede traffic to further improve road conditions.
• Slow down to a safe speed for current conditions.