Measuring influences of speed reduction on subjective safety.

In 1998 and in the beginning of 1999 in Lund (Sweden), preparations were made to introduce area-wide speed limitations to 30 km/h where the limit was of 50 km/h before. Several scientific projects that should accompany this implementation were started. The Institute for Technology and Society of the Technical University of Lund was involved in most of these projects, one of which was the development of a method to measure subjective safety and changes of it due to certain implementations. With the help of Focus-group interviews and additional road-side interviews with several open-ended questions, the character of events that were considered and/or experienced as dangerous was discussed and specified. Then, an instrument was developed and pre-tested, where such events should be ranked from lists in a standardised way, from subjectively most dangerous to subjectively least dangerous. After this ranking procedure, a question was asked how often different subjectively dangerous events happened in different areas of the city. The pre-test was done in Lund, and two areas in the larger neighbour town of Lund, namely Malmo, were chosen as the first model-towns to apply the new instrument: The two mentioned areas were different in several respects, the most interesting for us being that one was at many places equipped with traffic-calming infrastructure elements and there was a 30km/h-limit at some of these and also at some other places (= change of limit without change of infrastructure). The other area was a quite conventional arterial road, with a 50-km/h speed limit, and without any traffic calming elements. The two areas differ significantly with respect to the criteria that the instrument we had developed should measure: In the areas with lower speed limits and with traffic calming infrastructure elements, subjectively dangerous events occurred more rarely. In other words, the subjective safety situation was better in the area where according to the traffic planners the objective safety situation should be better. For the covering abstract see ITRD E123863.