Gritting salt
How salt prevents ice
Salt lowers the freezing temperature of water, which means it prevents ice or frost forming on the road when it falls to zero degrees centigrade.
Pre-salting the road forms a layer so that snow doesn't freeze on the surface and can be ploughed or churned off by moving vehicles.
Salt loses its effectiveness once the temperature falls below -8 degrees centigrade.
Traffic helps to melt ice
We spread between 10 to 40 grams per square metre depending on whether snow is forecast or is falling.
When spread on top of ice or snow, each grain slowly melts the surrounding ice working its way outwards. As it melts the ice, it forms a pool of salty water, which helps to melt the surrounding ice.
Where snow falls on top of salt then it begins to melt the snow from beneath.
Traffic speeds up the process by crushing the rock salt. Without any traffic the melting process will take longer.
About grit bins