The use of cost-benefit analysis in road assessments: a methodological inquiry.

BACKGROUND: Cost-benefit analysis is a useful tool for priority setting in road safety. The value of statistical life (VOSL) is a metric used to estimate the benefits of road interventions in cost-benefit analyses. The International Road Assessment Program (iRAP), for example, created a rule-of-thumb to calculate VOSL benefits of road infrastructure when performing cost-benefit assessments in countries where data on VOSL are sparse. AIM: To evaluate the rapid assessment metric developed by iRAP and provide suggestions for improvement in these methods. METHODS: We replicated iRAP calculations in order to make a critical assessment of the sources, results and conclusions. CONCLUSIONS: We found the iRAP metric a good example for highlighting some relevant aspects that should be considered in any VOSL estimation in order to enhance its use as a guiding principle for assessing road interventions. Specifically, we recommend the explicit disclosure of the assumptions, the use of sensitivity analysis and the avoidance of omitted variables bias.