Salt, sand and winter driving

GREEN BAY - You've seen them out on the roads before.

Crews salting and sanding. Trying to provide drivers with safe roads to travel on.    

But why can't salt alone do the job itself?

The first, simplest reason is temperature.

“Salt only works down for anti-icing or for deicing to a certain temperature. About 20 degrees is the optimal temperature. Below that, the regular sodium chloride won't melt the ice as effectively,” said Robert Bousley, operations manager at Brown County Public Works.

But if you think about it 20 degrees isn't that cold, and in Northeast Wisconsin, that threshold is crossed rather frequently.

And on the occasion that temperatures do drop below 20 degrees, if you see crews out on the road, they're not just going to be dropping sand. It's going to be a mixture of salt and sand.

“We mix the salt in with the sand to keep the sand from freezing. Because if we were to put sand, just straight sand, on the road, that would freeze as well because sand has a moisture content too. Sand we use more as a salt-sand mix, as an abrasive,” said Bousley.

And even though the salt-sand mix isn't melting snow, that abrasive sand is much better to drive on than untreated snow and ice.

The big key, Bousley says, is getting the ice and snow to melt before it gets too cold. 

Once the salt has mixed in with water on wet roads, temperatures have to drop below zero to for that solution to refreeze.

Bousley says salt is more expensive to buy, but that cost does not play a role in the department's decision making process.