Abstract
A way of evaluating an automatic queue-warning system is outlined. The main object of the evaluation is to measure the effect of such a system on road behaviour and road safety, although the overall journey time will also be examined. The chosen method of research entails before and after studies, if possible complemented with control groups. Furthermore, disturbing elements in the method of research will be discussed together with respective solutions. Finally, the number of accidents will be looked at that are necessary for a statistically reliable analysis.