Abstract
External costs caused by freight transport weigh upon the government or upon society as a whole. In this paper the different kinds of external cost caused by freight transport are described, as well as the methodology to determine these costs. It appears that it is possible to quantify the external costs of traffic accidents and the external costs of air and noise pollution. An important conclusion is that the aggregation level on which the analysis takes place has a large impact on the difference between internal and external costs. Future research should be focused on the quantification of the effects of certain activities on human being and the environment.