This study estimates and compares the external costs of road traffic accidents in Denmark, Finland, Sweden, Switzerland, the United Kingdom and (formerly) West Germany, using a common computational framework. A central feature of this computational framework is that we assume accident rates, i.e. accidents per vehicle kilometre, are independent of traffic flow. That means that a marginal car journey does not increase the risk for other car drivers and passengers but does increase the risk for pedestrians, cyclists etc. Then the marginal car journey will rise pedestrian and bicycle accidents per pedestrian and bicycle kilometre respectively. A second central feature is that casualties from road traffic accidents are classified as accupants and non-occupants with respect to the vehicles involved in the accident. This dichotomy of casualties is of great importance because in the computational framework of the study, the cost elements linked to casualties classified as accupants are fewer than the cost elements linked to casualties classified as non-occupants. The argument for this difference is that the occupants are assumed to have incorporated the marginal change in risk of being killed/injured as road users due to an extra journey to a larger extent compared to the non-occupants. This difference wille have implication for the valuation of the loss of life and limbs. As a consequence of the computational framework used, this study also shows that it is primarely the casualties among the non-occupant group of road users that give rise to external costs of accidents. For the different types of motor vehicles, external costs of road traffic accidents per kilometre of road use were found to be the highest for motor-cycles followed by buses, lorries and passenger cars. For the countries compared, the external costs are, on average, about five times higher for motor-cycles than for passenger cars. For lorries and buses, the external costs are about two and four times higher than for passenger car respectively. In the case of buses and lorries, practically all external costs are as a result of the death/injury of a person belonging to the non-occupant group of road users. The corresponding proportions regarding passenger cars and motor-cycles are some 2/3 and 1/2, respectively. The study also finds a substantial variation in the external costs among the countries compared. For example, the estimated external costs for lorries are twice as high in Denmark and Finland then in the United Kingdom and West Germany. The variation in external costs could to a certain extent be traced to differences in population density and to differences in the constructural design of the roads as well as to differences in the overall organizational flow of the road traffic. (Author/publisher)
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