Overview
Road safety has a high political priority, partly because of the large number of traffic casualties every year. During the last few years, a large number of measures to improve road safety have been studied. In order to be able to make a choice between the various measures, it is essential to judge them in an unambiguous way, in which other effects than road safety are taken into account. A cost-benefit analysis makes this possible.
The purpose of the report was to offer a practical guideline (to researchers) for the carrying out of cost-benefit analyses for road safety measures.
In a cost-benefit analysis, the future situation without the measure (zero or reference alternative) is compared with the situation with the measure (project alternative). In this, the project effects are distinguished from the autonomous effects. Then the project effects are included in the cost-benefit analysis and discounted during a longer period. Discounting means that those effects that occur later are weighed less heavily than effects that occur sooner. To do this, a discount rate is used. The present value of a project effect is thus a weighted summation during the analysis period.
Funding
Results
A practical applicable calculation method is described. Cost-benefit analyses of road safety measures at various levels can be carried out using this guideline. In this way, investment options can be weighed up against each other by, for example, determining policy plans, fixing the budget, or determining the prioritisation and phasing of investment options.
It is described what costs and effects have to be taken into account and what information is needed to perform a CBA. In a cost-benefit analysis, the future situation without the measure (null alternative) is compared with the situation with the measure (project alternative). In this, the project effects are distinguished from the autonomous effects. Then the project effects are included in the cost-benefit analysis and discounted during a longer period. Discounting means that those effects that occur later are weighed less heavily than effects that occur sooner. To do this, a discount rate is used. The present value of a project effect is thus a weighted summation during the analysis period.
Apart from a road safety effect, road safety measures sometimes also have a mobility effect. This effect can be direct because, for example, the maximum speed is lowered. It can also be an indirect effect because, as a result of a reduction in crashes, there are fewer tailbacks, the traffic system becomes more reliable, and the modal split changes. This leads to a change in the distances travelled and the choice of mode, whereby another road safety effect – now of the 'second order' – occurs. The mobility changes also have an environmental effect. A practical applicable calculation method is described. When the effects (safety, mobility, and environment) have been calculated, the social assessments are expressed in monetary terms.
Apart from individual measures, packages of measures can also be judged in a cost-benefit analysis. In this, the effects of the individual measures cannot just be added up. It is essential to determine the interference between measures with respect to four aspects: the costs, the size of the target group, the effectiveness of the measures, and any side effects.
If the present values of the investment costs and project effects have been determined, the social return can be calculated. If the return is positive, it is socially desirable to make the investment; the social benefits offset the costs. There are various return criteria, namely: the net present value (summation of the present value of costs and ben
Policy implications
Cost-benefit analyses of road safety measures at various levels can be carried out using this guideline. In this way, investment options can be weighed up against each other by, for example, determining policy plans, fixing the budget, or determining the prioritisation and phasing of investment options.