Once you get below -20 C (-4 F) salt loses a lot of effectiveness. Here in Edmonton we had a few weeks of ~-30 C and the roads were polished to an icy shine, t

Once you get below -20 C (-4 F) salt loses a lot of effectiveness. Here in Edmonton we had a few weeks of ~-30 C and the roads were polished to an icy shine, there was no getting away from it and no amount of sand or salt helped for any amount of time.