The spreading of salt and abrasives is one of the major challenges in snow clearing. It has to be continuously reassessed based on the temperature of the road and the amount of snow on the ground.
Salt is used in the winter to melt the snow and ice at sub-zero temperatures. The impact is limited in extreme cold weather. The temperature to watch is that of the road, not of the air, as it changes more slowly. The colder the road, the slower the salt is to act.
Salt works very well as long as the road temperature is above -5°C, below which its effectiveness gradually diminishes as it falls closer to -10°C. Below -10°C, it often has to be combined with gravel in order to give vehicles the necessary traction.
The key to effective and responsible spreading is to determine the RIGHT amount, the RIGHT location and the RIGHT moment.
In case of heavy snow fall, there is no advantage to spreading salt before clearing. Under those conditions, the salt gets too diluted and loses its effectiveness. During snow-clearing operations, crews will still spread some salt because the salt spreaders have front and lateral blades that scratch the snow before spreading the salt. After that, once the precipitation stops, more salt is spread if it is not too cold and the snow has been completely cleared off the roads.