Towards a method to forecast the effectiveness of national road safety programmes

During the last three decades a more rational approach to political decision making has produced an increasing demand for scientific evaluation. A common understanding of evidence-based policy is that any new measures should have been proven to be effective. At best, these kinds of methodologically sound evaluation studies show the effect of a measure in a given situation. The results are then an essential basis for the design of a broader safety policy. However, at present there is generally little understanding of the effect of the measure in another situation, or of how it would interact with other measures in a programme. Yet, it is precisely such questions that need to be answered if the requirements of policy makers are to be met. Politicians need to be able to estimate whether the expected benefits of a programme justify the investment. Therefore, evidence-based road safety policy should not rely solely on evaluation studies of single measures and ex-post assessments of safety programmes. The method outlined here is for the ex-ante estimation of the potential of a road safety programme, which takes into account existing scientific research, an estimate of the degree of implementation that can be expected at a certain point in time, and the interaction between individual measures.