Report numberRA-MOW-2009-003
TitleManual for evaluating road safety measures
SubtitleA first step
AuthorsFredriek Van Malderen
Cathy Macharis
Published byPolicy Research Centre for Mobility and Public Works, track Traffic Safety 2007-2011
Number of pages62
Document languageDutch
Work packageOther: Evaluation techniques

The evaluation of road safety measures is an important task to achieve the desired and intended goals in an efficient and effective manner. There are various methods to evaluate these measures. There is the popular social cost-benefit analysis, the (multi-actor) multi-criteria analysis, the cost effectiveness analysis, the impact analysis and the economic impact analysis. The choice of the evaluation method depends on the situation. A wrong evaluation method in a given situation can lead to wrong results, causing wrong conclusions which result to incorrect choices in the policy. To select the most appropriate evaluation method, we are developing a decision tree based on concrete questions.

A first question is whether the measure should be evaluated ex-ante or ex-post. In the ex-ante or prospective evaluation, the effects of the measure are pre-estimated. Hereby, future positive and negative impacts are identified. The ex-ante assessment gives the policymaker more understanding. The side effects, effectiveness and/or efficiency problems of the measure are coming to the surface in this evaluation. The opposite of ex-ante research is ex-post evaluation. This research is based on historical and descriptive data. The number of available alternatives has an influence on the choice of the evaluation methodology. If only one alternative is available, there is no need for ranking the alternatives as the (Multi-Actor) Multi-Criteria Analysis (MA) MCA does. In this case, it is better to use a social cost-benefit analysis or a cost effectiveness analysis. The monetary nature has also an impact on the preferred methodology. If the effects of the measure are mainly non-monetary based or if it is difficult to monetize the non-monetary effects, it is better to use a multi-criteria analysis (MCA) where the effects should not be monetized. If we want to examine the individual interests in the measure per stakeholder, a MAMCA method should be used. The cost-effectiveness analysis can be applied when only one goal has to be measured and if the costs are clear. There are four approaches in the ex-post evaluation. The after period, the before-after period, whereby the effects are determined before and after the implementation of the measure, the control group and test group approach and finally the combination of before-after approach and the control and test group approach. The way the control group is compiled, arbitrary or involuntary, determines the design of the research: non-experimental, quasi-experimental or experimental.

There is also a step-by-step plan in this manual. In this way, we want to add more uniformity in the evaluation process. It starts with a problem analysis. Afterwards we try to resolve the problem. We then proceed to the development and pre-selection of the alternatives. In the next step the criteria are selected, the impact of the alternatives are determined and the effects are valued. In the second last step of the ex-ante evaluation, the ranking and evaluation of the policy alternatives are conducted. Afterwards there is a feedback. Finally, a summarizing report is made. After implementing the measure, an ex-post evaluation is performed. We must examine whether the measure has achieved the desired and intended effects.

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The Policy Research Centre for Traffic Safety carries out policy relevant scientific research under the authority of the Flemish Government. The Centre is the result of a

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