Why doesn MassHighway put salt on the roads before it snows?
Putting salt on road surfaces prior to a snowfall wastes time and money since salt often bounces from the dry road during application and, the portion that manages to land in the right location is subject to wind- which blows it off the road before it can do its job. Salt is most effective after snow has accumulated and the temperature is 20 F or higher. Under these conditions, the salt and snow will mix, melting snow into slush that can be plowed off the pavement. This melting action will occur within two hours, less if traffic is using the highway. If the temperature is below 20 F, the salt will have difficulty melting the snow and ice, so other methods are used. Abrasives are put down for traction, and calcium chloride can be added to enhance the ability to melt the ice and snow.
