THE DANISH CO-ORDINATED ACCIDENT STATISTICS

The Danish Road Directorate has published results of the so-called co-ordinated accident statistics concerning the five-years-period 1976-1980. The purpose of the co-ordinated accident statistics is to analyse accident numbers as functions of the traffic flow on different types of road sections and intersections. The results are used for pointing out black spots, i.e. road sections and intersections with a particularly high accident load. They are also used when evaluating the effect on road safety of a proposed road project. The co-ordinated accident statistics cover a road network of almost 7500 km consisting of all Danish trunk roads (4500), highways in 8 of the 14 Danish counties (3000), and 130 km of roads in a single municipality. The road sections are divided into a number of types dependent on the width of the road, ribbon development, etc while the type of an intersection is determined by the number of arms, regulation, channelization, and ribbon development. The statistics deal with traffic accidents reported by the police during the years 1976-80, which amount to a total of 25500 accidents. Of these 5500 occurred at major intersections, and 20000 on road sections in between. A similar study two years ago unveiled some interesting findings for road sections. For intersections, however, the results were incompatible with experience. The way in which the traffic load of the intersections is calculated has now been changed. The results of the co-ordinated accident statistics 1976-80 are now compatible with experience for road sections and for intersections as well. The paper will carefully describe the models, and the accident characteristics of the different types of road sections and intersections will be discussed. Finally examples of the ways in which the results are used in traffic planning practice will be given. (TRRL)