This morning throughout the greater Twin Cities metro area, including Wright County, there were hundreds of crashes and spinouts despite a mere dusting of snow. The culprit? Black Ice.
Black Ice can be created by frozen drizzle and rain, but can also occur when temperatures drop in the double-digits below zero. Wright County Highway Maintenance Supervisor Steve Meyer explained how this phenomenon happens in Minnesota in the dead of winter – even without precipitation.
“In weather like this, it comes from car exhaust,” Meyer said. “With the amount of ethanol that we use in our gasoline, we get a lot of car exhaust. It’s most dangerous and noticeable at stop lights and roundabouts, because it starts to build up from the exhaust from the vehicles and it’s clear – making it difficult to see that the roadway is getting slippery.”
The Wright County Highway Department has been treating the areas where black ice is most likely to form – at intersections and areas like roundabouts where vehicles are running, but routinely need to stop or slow down considerably.
Meyer said the big trouble spots are when there is a crash or a stalled vehicle on the side of the road that forces traffic to stop or slow down. Warm exhaust hitting frigid air can cause the vapor to condense and literally drip out of a muffler. It’s much more of an issue in areas with stop-and-go traffic as opposed to rural roads and highways
“This type of black ice is more common in areas where there is a heavy volume of traffic and it’s either moving slowly or stopped,” Meyer said. “All that moisture created by the exhaust just drops on the road and freezes.”
Meyer said you won’t see traditional salting trucks out on the roads over the next week because road salt is ineffective when temperatures are as cold as we are experiencing. The Highway Department will treat trouble spots with liquid de-icers and a product called “Ice Slicer” – a granular product consisting of complex chlorides that last longer than most de-icing products and provides better traction for tires on slippery surfaces.
“It will be a problem for most of this week, especially during the day when the traffic volumes pick up for the morning commute,” Meyer said. “That’s when temperatures are at their coldest. It’s going to be an issue drivers will need to be aware of. The number of crashes and spinouts this morning throughout the metro area was way up from normal and it will likely be a problem until the weather warms up and this system works its way through.”