Safety and travel time in cost-benefit analysis: A sensitivity analysis for North Rhine-Westphalia

Decisions on large-scale infrastructure concepts are frequently based on cost benefit analysis (CBA). Using 431 road projects evaluated in the integrated transport planning process in North Rhine-Westphalia, Germany (IGVP NRW) this paper examines the evaluation dimensions traffic safety (fatalities) and travel time in private passenger transport. The unit values of traffic fatalities and travel time are varied, and the effects of the variations on the rank order of the projects are examined. Target conflicts between safety and travel time are studied as well as the contribution of these two dimensions to the total benefit values. The sensitivity analysis shows that the evaluation results are fairly stable against variations in unit values of travel time and fatalities. The relevance of traffic safety in terms of its contribution to total benefit as well as in terms of the unit value appears to be relatively minor. The unit value of travel time is higher than that of lifetime. Some projects turn out as feasible in the evaluation even though they are likely to increase the number of fatalities. The paper therefore suggests the higher weighting of traffic safety in CBA.

Research Highlights
► CBA results of 431 road projects are used for a sensitivity analysis in which the unit values of traffic fatalities and travel time are varied.
► CBA results are fairly stable against variations in unit values of travel time and fatalities.
► Unit value of travel time is higher than that of lifetime.
► Some projects turn out as feasible in CBA even though they are likely to increase the number of fatalities.
► The paper suggests the higher weighting of traffic safety in CBA.