During and after a winter storm, crews in affected areas work around the clock to monitor changing weather conditions and treat roads.
The N.C. Department of Transportation has more than 1,900 trucks that can be equipped with plows and spreaders to remove snow and ice. If needed, NCDOT moves trucks and equipment from areas less affected by a storm to areas more affected.
Depending on conditions, crews might pre-treat roadways with a salt-water mixture called brine to help keep ice from bonding to the pavement. After plowing roadways, crews use salt, sand – or a mixture of both – on road surfaces. Salt helps melt ice and snow, and sand provides extra traction.
A solution made up of water and 23 percent salt, Brine is used to pre-treat roadways in dry conditions when the temperature is above 18 degrees Fahrenheit.
The decision to pre-treat roads is made 24 to 48 hours before a storm, and brine must be applied when it is not raining. Rain dilutes solution and washes it off the road, making it ineffective.
Among several benefits, brine:
- Lowers the freezing temperature of water to about 18 degrees Fahrenheit (8 degrees below Celsius)
- Prevents snow and ice from bonding with the road's surface
- Keeps snow from being compacted by traffic, which can turn it into ice
- Is more effective and coats roadways better than plain salt or sand
- Gives crews time, since brining can occur up to 48 hours prior to a storm
- Costs 15 cents per gallon to produce. One mile of a single lane of road can be treated for about $6; rock salt costs about $14.38 to treat the same stretch of road.
Brine is made by loading a hopper with salt and water and agitating the ingredients until the solution is 23 percent salt. The solution is then pumped into a holding tank and loaded onto trucks to be sprayed on roads.
NCDOT crews will sometimes use a brine blend with 10 percent calcium to remove snow and ice during and after a winter weather event. This solution can be used in combination with rock salt when temperatures are lower to keep the salt working longer.
Salt & Sand
Crews use salt and sand to help clear roads when a storm hits. After plows clear as much snow as possible, a mixture is spread on roads, with special attention given to freeway ramps.
Salt works to melt the remaining snow and ice. Sand helps break up the ice and adds extra traction to help vehicles stay on the road.