In general, due to the large difference in traffic on the left and right lane on dual roads, it is more difficult to prevent slippery conditions on the left lane in winter time. Traffic has an eroding effect on the impact of skid protection and therefore greater us of material (like salt) for skid resistance may be required in the left lane beyond the right to offset the eroding aspects. The project will specify and compare in which lane winter accidents (due to slippery and icy conditions) have occurred.