This paper deals with the evaluation of countermeasures implemented in order to increase the traffic safety. On the basis of information on the number of casualties in accidents reported to the police and information from travel habit surveys, it has been possible to quantify the risks for various road user categories on a national level. High risks are associated with small degrees of exposure and low risks with high degrees of exposure expressed in person kilometres. The difference in travel speeds between different road user categories results in increased risks for motor vehicles, especially for car drivers. Each countermeasure or change in traffic may alter the traffic safety situation in different ways. The effects may be changes in the exposure, risk and consequences of the accidents or personal injuries. Speed limit is one countermeasure which influences both exposure, risk and consequences. Increased fuel price may influence exposure, better road standards may reduce risks and increased use of safety belts may reduce the consequences of accidents. Measures such as road markings and reflective posts along the road do not, in many cases, provide the expected effect since speed increase. This means that an expected decrease in the accident risk is reduced or does not occur at all while the consequences of accidents increase. The regression to the mean is another problem discussed. For the covering abstract see IRRD 273472.
Abstract