The study constitutes the basis for the model to be used as a guideline for determining winter road standards within the framework of the public economy. Winter speeds vary widely, but can be estimated for passenger cars as 75-90% of those on bare roads. For constant stopping distance, speed should be halved. Speed reduction is determined more by the appearance of the road than by friction/road traction. Precipitation entails greater reduction than slippery road surface alone. Accident rates on winter roads vary. Studies based upon observation of road conditions and traffic measurements show increased risk on icy/snowy roads. The more unusual these conditions, the greater the risk. Aggregated studies do not support the presumption of increased risk in winter. Statistics from the Swedish Motor Vehicle Inspection Co. were analysed in light of notations of rust damage that caused cars to fail inspection. In Vaestervik, where roads are salted, cars fail inspection 2-4 times more often than on Gotland, where salt is not used. Experts estimate that the lifetime of cars would increase by 25% if roads were not salted, but that costs will continue to be high as a result of corrosion to electronic equipment. Several knowledge gaps are identified. (A)
Abstract