External costs of transports imposed on neighbours and fellow road users

Abstract: This thesis consists of an introductory chapter and four research papers, summarized as follows. The overall purpose is to study various external effects of the transport system; effects that are not considered (or not fully considered) today. The first paper estimates the relationship between accident frequency and homogeneous and inhomogeneous traffic flows, which is useful for calculating the marginal external accident cost of the traffic flow. We find that important information is lost if differences between traffic modes are not considered. The indication is that an additional vehicle on the road decreases the accident risk. Separating the traffic flow into cars and lorries, we find that an additional car increases the accident risk whereas an additional lorry lowers the accident risk. The second paper, a literature overview, discusses the value of road and railway safety by combining the results of psychological and economical studies. Various factors that possibly influence individuals? perception of risk and their willingness to trade risk for money are examined. We find that the use of different values within different contexts may be motivated. The findings imply, furthermore, that studies estimating the value of safety should focus not only on disparities between transport modes per se but also on disparities between accident types. In the third paper, the choice experiment approach is used to assess people's preferences regarding railway transports of hazardous materials. Exposure to hazardous materials is used to describe various transport configurations. It is shown that the choice experiment method as well as the use of exposure can be applied within this area. In the final paper, preferences regarding road transports of hazardous materials are examined. The method and design are the same as used in the previous paper but with special attention given to the presence of biases. The presence of hypothetical bias is tested for by the use of self-reported degree of confidence, and the presence of a focusing effect explored by the inclusion of information on other fatal risks. We find that there are no major differences in individual preferences regarding hazardous materials transported by rail or road. It is also found that individuals that are confident in their answers express higher values of willingness to pay (accept a compensation) for a reduction (increase) in exposure. Finally, no focusing effect can be detected.