The purpose of the ROAD TRAFFIC IN WINTER -research programme was to search for the social optimum between studded tyre usage and winter maintenance. The programme consisted of over forty separate researches concentrating on: - traffic safety - environmental effects - maintenance - vehicular costs - road user experiences. The total costs of nine alternatives according to different salting policies (basic 120 000 t/a; light 60 000 t/a; nearly unsalted < 30 000 t/a) and stud usages (basic > 95% of cars with studs; about 50%; < 20%) were calculated. It seems that the basic situation (when the research programme began) is economically better than any other of the studied alternatives. From the perspective of Finnra, reducing the use of studded tyres and the amount of salt from the basic situation by half, would be most favourable. The decrease in stud and salt use would be beneficial also for the environment, but the no salt and studless alternative would not, however, be most economical. For the driver roads without salt and tyres without studs offer the most favourable alternative. When searching for the social optimum, the most important factor is accident costs, which in the studless and unsalted alternative are extremely high. Accident costs weight the result towards the existing alternative i.e. the use of salting and studded tyres should be continued despite of the disadvantages. Studded tyres give added safety especially to insecure drivers in varying road conditions. Salting also evens the variations in the circumstances and allows safe and flowing traffic in the winter.
Abstract