The driver's exposure to risk of accident.

Abstract

The driving habits in three population groups in Central Sweden have been investigated by means of a mailed questionnaire containing questions about the previous calendar year and a driving journal for the subsequent week. The samples totalled 22575 individuals. The non-response was 15%, 19% and 10% respectively, but has not been found to affect the results to any great extent. There were appreciable differences in age and sex as concerns average distances driven, distribution as to type of motor vehicle, time of day and week, driving in rural or built-up areas, on working or spare time, etc. The most interesting groups at risk were the oldest and the youngest drivers. They had in common relatively low average mileages, and to a great extent rode mopeds and drove during their spare time. The youngest, in addition, drove relatively often during the night hours, with borrowed vehicles and in built-up areas. Driving experience (in number of years since the first licence) and age influenced the average mileage in contrary directions, i.e. mileage decreased with passage of time since the first licence and increased with age. The accident frequency per distance driven seemed high for lorry, moped and motorcycle. It was high among the youngest and the oldest drivers, among those with less than five years of driving experience and finally it was high during the night. On the whole a large part of the differences in accident rates was explained by the exposure to risk. Even traffic offences were a function of this exposure. The conclusion drawn from the discussion is that motor vehicles have a central bearing on the population, that the risk differs radically between driver groups and that it should be possible to devise preventive measures out of these differences.