This paper presents a procedure for using recent safety estimation theory and benefit-cost analysis to accommodate uncertainty in accident frequency estimates while addressing the specific decision-making problem at hand. In the procedure, a site can be treated if thedifference between the safety benefit and the treatment cost - the net benefit - is large enough. Recognizing that safety benefits varyacross sites and treatment types, the procedure allows a budget to be allocated to different programmes but ensures that the smallest net benefit - the net marginal benefit threshold - is the same for all programmes. The procedure estimates the number and costs of sites for each treatment type for which the net benefit exceeds a specificthreshold that is adjusted such that the total treatment cost is inline with the available budget. While this methodology can be useful for agencies responsible for road safety improvements, the data requirements could pose a problem for some jurisdictions. A further difficulty is that the computations required are extensive, particularly in cases where uncertainty to other data items requires the use of sensitivity analysis. To facilitate these computations, a computerprogramme is available from the authors. (A).
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