Studded winter tyres and traffic safety.

This paper presents the results of two Icelandic studies of studded winter tyres and traffic safety. Two sets of data from the accident database at Reykjavik were used, for the periods 1983-88 and 1989-95. Only good winter tyres were compared with studded tyres, and cars with two winter tyres and two studded tyres were excluded. The two periods are not entirely comparable, because the accident database includes only accidents reported by the police and, from March 1988 on, it was no longer necessary to inform the police of an accident. The database subdivided people involved in accidents into 'perpetrators', who made at least one mistake leading to an accident, and 'victims', who did not help to cause an accident. For each period, the samples of perpetrators and victims were approximately equal. The paper's tables give statistics for accidents involving perpetrators and victims, for studded tyres and winter tyres, and for dry or wet and ice or snow conditions. The tables show the excess safety of studded tyres for the first period (for all accidents) and for the second period (for all accidents and for injury accidents only). Most of the differences show that drivers using studded tyres drive more safely, for both dry or wet and ice or snow, but there is a slight unexplained difference perhaps related to studded tyre use.