Traffic safety on urban streets : the problem and how to assess it.

This paper intends to give a short overview of the urban traffic safety situation in Sweden. Focus will be on what type of accidents are most common in this environment and what affects the number of these accidents and their severity. Also the principles of the Swedish assessment models for this area will be presented and discussed. Especially the modelling of safety on links (streets) in the network will be addressed. The traffic safety situation in Sweden is at the moment one of the best in the world. There are however still a lot of casualties in traffic. The Swedish 'Vision Zero' aims at having zero dead and severely injured in the traffic system in the long run but there's still a long way to go before the Vision Zero is anywhere near a reality. Every year in Sweden about 500-600 people are killed in the traffic, and approximately 4000 are severely injured. Out of these 30 per cent of the fatalities and 45 per cent of the severe injuries occur in built-up areas. Compared with the rural environment, the urban traffic environment leads to approximately the same amount of injuries, but only half as many fatalities. The most common urban injury-accident is a collision between two motorised vehicles. These accidents make up about 40 per cent of the total amount of injury accidents. The fatal accidents are instead dominated by motor vehicles involved in accidents with vulnerable road users and motorised vehicles in single accidents. How can we best use this information? When it comes to modelling safety for the streets between intersections several problems arise. Some of these will be discussed in this paper, for instance: How do we deal with small intersections which are not large enough to be modelled separately but instead will be included in the street-effects?; Which variables are the best predictors for the amount and severity of accidents?; What criteria should the models satisfy depending on what we want to use them for? (A) For the covering abstract of the conference see ITRD no 207828. The reprints are also available at the web - http://www.vti.se/pdf/reports/K18APart1.pdf; http://www.vti.se/pdf/reports/K18APart2.pdf and http://www.vti.se/pdf/reports/K18APart3.pdf.