Multiobjective Methodology for Highway Safety Resource Allocation

Decision making in improving highway safety involves minimizing the frequency and severity of vehicular crashes by selecting countermeasures and allocating resources optimally among various competing highways. In the current sociopolitical and economic environment, the decision to implement highway safety improvements should be based on a credible methodology that accounts for more than one objective. Objectives in highway safety, however, usually conflict with each other; for instance, putting more effort in crash rate reduction invariably results in an increase in the associated costs. These objectives are often noncommensurable, where one may want to minimize cost of countermeasures, which is measured in monetary units, and safety, which may be measured in crashes in million vehicle miles of travel. This paper presents a multiobjective methodology that keeps the objectives in their respective units and provides a set of solutions, rather than only one, which is most logical for a multiobjective problem. The major tasks were (1) identifying the predominant causal factors on each road segment under consideration, and the appropriate countermeasures for these factors; (2) identifying the functional relationships between the crash rate and the cost of implementing the identified countermeasures; and (3) using the multiobjective analysis to select the best countermeasures and allocate the available resources optimally.