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A storm is on the way, and when that happens, you'll often see the Minnesota Department of Transportation's (MnDOT's) trucks (and Rochester City trucks, too) out there spraying the streets with what a lot of people think is just water. Here's what it really is and why they do it.

Today on Rochester Today, MnDot's District 6 Spokesperson, Mike Dougherty, answered a lot of questions for us, but especially hit on how the stuff they're spraying is some water and some salt...brine. Click play to listen, or scroll on down and read the conversation.



JAMES RABE - Today, we've dedicated the show to figuring out what's going on in dot Mike's world all the time. I see people saying, why are they putting water on the roads, like on 52? And it's not, it's a brine, but what is it?

MnDOT MIKE - BRINE is, um, essentially saltwater. So it's a, it's a saltwater mix that we use. And it's, I think it's about at 24% salt solution. And they found that putting down just a, it's almost like a mist it's, it's, it's a little more than a mist, but essentially putting that down in certain areas where, um, there might be some traction issues later, it's sort of a pre-treating type, um, situation that it goes down often. It'll dry, um, in advance, but once the snow starts hitting it, we've got a mix of a salt layer between the pavement and the moisture that's coming down in the air. And that helps with our crews then, as they're trying to scrape that off, because otherwise we can get that, that snow comes down and there's nothing down on the pavement yet, uh, that those vehicles will compact it and more shut down.

Like if you drive through your driveway, after a fresh snow, you haven't shoveled pack that down. Then you transfer that to a highway where thousands of vehicles are coming through, packing that down, that can become a compaction isolator. So that helps us, you know, on say like bridge decks or, um, ramps, uh, highway ramps, things like that, where it can get that layer. And it just gives us a little bit of an edge. Um, you won't see it all the time that we put it down, but during the lot, um, and I know like, uh, different entities, do you all sit around our city streets here? You can sometimes see those white little squiggly lines after it's dried up, but it gets there. And it'll, and it's, it's another way to, to use less salt because you think about it, you know, it's, it's, we're only using 24% salt in the water. So, um, it's, it's good for the environment. We're not using as much salt on the roads then, or our salt usage will go down. Um, and also not spending as much money on salt as well


JAMES RABE - Why not use sand?

MnDOT MIKE - It doesn't melt snow. So that's the tough part. So sand is good for, um, where you have really, you know, icy conditions and give you a traction usually, um, on, on slower speed roads is probably your best option. So that's why you might see it more. I had intersect city intersections in town, on residential streets where say, you need to come up and there's a stop sign before you cross an intersection. You know, you really want to be able to stop there and there's you get that grit. Um, and they may put down the sand, but the sand is, is tough to clean out and it clogs up the drainage areas.

Also, if you put sand on, on you think about like a highway speed road, um, the folks driving behind you are going to get sandblasted, you know, cause that fan is going to kick up. Um, so there's, that's why we, we, we do use a little bit of sand, but often again, it's like at a, at a ramp where you need to come off and come to a stop, um, maybe on a curved road where there's a significant curve or something like that. But, um, we use it pretty sparingly, um, on our highways, just because of that.

You can hear the entire show by clicking play.

As always, if you have a comment, complaint, or concern about something I wrote here, please let me know: james.rabe@townsquaremedia.com

Listen to James Rabe and Jessica Williams Weekday from 6 - 10 AM on Y-105 FM

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