Dynamic speed adaptation based on information technology

In order to define critical situations in which speed adaptation is unsatisfactory a number of traffic safety researchers from 20 countries were asked to rate the seriousness of various situations. The proportion of injury accidents in the different situations were also considered. Expert judgements, the high proportion of injury accidents and the increased accident risks compared to "normal" conditions show that road surface, visibility and weather dependent situations are most critical considering speed adaptation. Improved speed adaptation has the largest safety potential in the following situations: - Road surface-, visibility and weather affected situations (e.g. slippery road, fog, darkness). - Places, where drivers after prolonged driving at high speeds have to adapt the speed to a lower level to be able to negotiate the situation (e.g. motorway exits, sharp bends). - Encounters with crossing-course both between motor vehicles and between motor vehicles and pedestrians/cyclists (e.g. at intersections, at zebra crossings). When it comes to the introduction of different in-car systems, driver acceptance is of a great importance. Therefore, a nationwide survey among 1000 Swedish holders of driving licence was carried out. The results of the survey have shown that the majority of the respondents were positive to a device which automatically lowers the maximum possible speed of the car in slippery conditions and poor visibility, as well as to a device which warns the driver or reduces the speed automatically if the car is about to collide with another road-user. A general speed limiter which prevents exceeding the prevailing speed limit is accepted by one third.