Some DC area roads weren’t pretreated before Friday’s snow. Here’s why.

WASHINGTON - One of the telltale signs that snow is on the way in the Washington, D.C. region are the white stripes that appear on roadways about a day before the storm hits.

The lines are formed when a type of anti-icing pretreatment solution called liquid sodium chloride, or brine, is sprayed on the road surface. The chemical prevents a bond from forming between the pavement and the snow and ice after the precipitation starts.

Some DC area roads weren’t pretreated before Friday’s snow. Here’s why.

But some road crews in Maryland and Virginia didn’t rely on that tactic this time around. Why? If wouldn’t have been effective, they say.

Virginia Department of Transportation spokesperson Alex Liggitt told Barnard that crews did not heavily pretreat the roadways prior to Friday morning’s storm because roadways already had a substantial amount of salt and brine from treatments put down earlier this week. 

Chris Conklin, Director of the Montgomery County Department of Transportation, said his crews did not pretreat for the same reason.

VDOT’s Kelly Hannon says road crews have to look at all aspects of a storm, like how and when it will start, and what the temperature is like – before pretreating.

"Yesterday in our area, it was obviously very cold. And if you put down brine, a liquid, in very cold temperatures, you actually run the risk of creating icy conditions," Hannon said.

Road crews across the region use a combination of pretreatment, anti-icing, and de-incing methods to keep highways and side streets clear during winter storms.

On Friday, the storm quickly dropped heavy snow on area roadways, making it difficult to maneuver and to tell where the street ended, and the sidewalk began.

Between two and four inches of snow are expected to fall Friday as the storm moves across the region.