A higher percentage of one vehicle accidents occur on the A- 28 highway between the cities of Assen and Groningen than on any other highway in the Groningen province. Not all accidents can be explained by pavement defects such as asphalt roughness. Research was therefore undertaken to ascertain the reasons for the higher level of accidents. Four areas of research were undertaken: (1) systematic accident analyses (2) inquiry on dangerous locations at regular users of a road section (3) video- observations of driving behaviour, and (4) behaviour observations in an instrumented car. While in these four sub- divisions only little was known about speed behaviour, a study was made to determine the relationship between the traffic, speed, and accident levelfor a number of locations. Four locations were selected, two study locations and two control locations. The locations were selected on the quantity of accidents during nine years. To analyze the speed image, speed measurements were made on the right traffic lane of each location. It is shown that for each location, there is a relationship between the intensity and the standard deviation of the speed. A relationship between traffic concentration and average speed is shown only on one of the four locations. If the intensity increases suddenly, for instance at access or exit roads, the average speed decreases.
Abstract