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 to areas more affected by a storm.
Depending on conditions, crews might pre-treat roadways with a mixture of water and salt called brine to help prevent ice from bonding to the pavement. After plowing roadways, crews use salt and sand – or a mixture of both – on road surfaces. Salt helps melt ice and snow, and sand provides extra traction.
Brine
Brine, a solution of water and 23 percent salt, is used to pretreat roadways in dry conditions when the temperature is above 18 degrees. The decision to pre-treat roads is made 24 to 48 hours before a storm.
Brine must be applied when it is not raining. Rain dilutes the solution and washes it off the road, making it ineffective.
Among several benefits, brine:
- Lowers the freezing temperature of water to about 18 degrees (-8 degrees 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 before 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 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 helps to melt the remaining snow and ice. Sand helps break up the ice and adds extra traction for vehicles.