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The science MoDOT uses to keep roads clear in the winter

The salt you use on your sidewalk each winter is, at its base, the same as what the Missouri Department of Transportation uses to clear our roads. With that said, their methods can be a bit more complex.

"There are a few routes we use straight salt on, but primarily there’s a mixture of material because we want the abrasives there for traction as well as the salt for melting purposes,“ MoDOT District Maintenance Engineer Jason Shafer said.

Shafer says MoDOT mixes salt with rough and gritty materials such as sand or rock chips to give drivers traction while the ice or snow melts. Even with traction, there are times when it’s too cold for salt to work effectively. Anything below the mid-20s and "it starts to lose effectiveness rapidly," he said.

During a winter storm last February, “our salt really wasn’t effective at that point, because it was simply too cold,“ Shafer said.

For temperatures in the low 20s and below, MoDOT looks to a salt brine solution. Shafer said salt levels in the solution can be configured to allow it to work at colder temperatures, but there's also a limit to this. But the mixture can work in sub-zero temperatures if the mix is strong enough, he said.

The saltwater mixture has other applications, as well.

“The brine we will use a lot of time, so if we’re going to treat in advance of a storm, we’ll go ahead and spray roads and bridges down with the brine,“ Shafer said.

Crews also apply beet juice to roads in certain conditions. The sugar in the juice helps the salt stick so it doesn't blow off the road.

With all the variables in a winter storm, MoDOT says its treatment plan will usually be a custom fit.

“I’ve always said storms are a lot like people," Shafer said. "They all have their basic, or their different quirks, and you need to know how to respond to them. So, you know it’s going to depend on how wet it is in advance of this storm, the type of snow, if it’s a wet or a dry snow, and then your ambient temperatures too throughout the storm and on the tail end of it as far as really what the best way to treat it is.”

Even with all of this technology and planning, treatment materials will stick to and damage your vehicle. Devin Kelley, owner of Allstar Automotive in Columbia, says the best way to fight this is the old-fashioned way.

"Some manufacturers have started spraying undercoating on their vehicles," Kelley said. "I know Hyundai has an undercoating that they do on a lot of vehicles these days that helps protect them, but keeping them clean is one of the best ways things you can do to protect your vehicle from accelerated oxidation."

Of course, all of this means crews have to be out on the roads in the most treacherous driving conditions, so Shafer asks that drivers give road crews space this winter -- for everyone's safety.

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John Ross


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