What is that stuff they're spraying on icy highways?




Posted on December 29, 2009 at 6:24 PM

Updated Wednesday, Dec 30 at 12:51 AM

DALLAS — The Texas Department of Transportation had to learn the hard way to get out and pre-treat the roads when a snowstorm is expected. 

On Christmas Eve, the agency had to shut down the very busy High Five interchange in North Dallas after it became impassable (Remember that slippery sliding mess?).

Fast-forward to Tuesday and you could tell that TxDOT did not want a repeat of last week.

Crews were out early pre-treat the High Five with magnesium chloride. The chemical compound sticks to road surfaces, helping to ensure that drivers don't get stuck in a jam. 

"What they will do is spray the right lane. They have to keep one lane open so that's the idea to spray that on there and it'll stick and will prevent ice formation," said TxDOT spokeswoman Michelle Releford.

The liquid de-icing material is made of natural sea salt, and is considered safer than the alternatives.

"That's one of the reasons we use it,  because it is the least corrosive thing we can use," Releford explained. "Once it absorbs water, it evaporates." 

Alan Walne, the owner of Herb's Paint and Body, says the magnesium chloride is not damaging to a vehicle's paint job, but it can be pretty stubborn.  "It also has a little consistency to it that kind of feels kind of gummy," he said. "Get it on the windshield and it'll smear, and it doesn't want to wipe off real easy. The primary thing is just to get it clean — clean your car up after a snowstorm."

Some reports suggest that repeated travel over winter months can cause magnesium chloride to build up --  and that, in turn, can deteriorate wiring insulation and cause serious damage to electrical systems.  The state of Colorado is questioning the safety of magnesium chloride.

But Walne says his shops have seen no problems underneath vehicles that have been driving over treated roads and highways.

"In today's world, with all the corrosion-proofing that all the manufacturers are using on the later model cars, that's probably not going to be a real significant issue,"  he said.

The bigger issue — since Texans don't get much snow in the winter: Slow down, and don't hit the brakes on icy  bridges and overpasses or your vehicle could spin out of control and you could become a customer of Alan Walne.

E-mail ddenmon@wfaa.com