DES MOINES, Iowa — This weekend’s snowstorm wasn’t a typical January snowstorm. Central Iowa started the evening with freezing rain, sleet, and wet snow, mimicking a late fall/early spring snowstorm rather than a mid-winter one. As road temperatures hovered around the freezing point of 32°, slush formed on the roadways. By the late evening, colder temperatures at the ground level and the mid-levels of the atmosphere allowed for a light and fluffy snow to fall.
Much of the metro area picked up 10 inches to 14 inches of snow on top of the slush that inevitably froze underneath. Des Moines Public Works Director Jonathan Gano says main roads would have been a lot worse had their crews not pretreated them with a brine mixture made of salt and water.
“That bottom layer is very difficult to remove without having salt underneath it. Otherwise, with 14 inches of snow pressed down, you’ve got to burn through it with a lot of salt if you’re trying to work that salt from the top down,” said Gano. “So pretreatment saved a lot of time, energy and effort, and it allowed us to deliver safe road conditions much faster because we had salt underneath the snow and on top of the snow and that let the plows push it all off.”
However, in Des Moines there are 2,200 miles of streets, and about two-thirds are residential streets. Residential streets are not treated the same as the 750 miles of main roads that are in Des Moines. The main reason? It’s expensive! Gano said, “If we were to step into treating all of the roadways exactly like we do snow routes, the initial expense in year one would be an additional $4.5 million.” A lot of those roads are low volume and low-speed routes where the speed limit is already 20 mph to 25 mph, which should prevent most, if not all crashes.
The job doesn’t stop beyond clearing the 2,200 miles of streets. Des Moines Public Works continues to monitor roads for days and even weeks after each snow storm due to the possibility of snow melting and refreezing. With bitterly cold temperatures expected to follow a warm up on Tuesday, this will create some challenges.
“It can even get cold enough to defeat the ability for regular salt to melt it. So we add chemical accelerants to it to permit the freezing point to go even lower so that that ice can melt and run off the roadway so that people can have safe driving conditions,” said Gano.