Multicriteria Aid to the Choice of Road Surfacings

Multicriteria aid to decision-making is a set of theories and methods designed to assist decisionmakers in selecting one out of several possible alternatives while considering various points of view or “criteria”. In managing their assets, road managers are often faced with the difficult choice of type of surfacing to suit a given situation. In making this choice, they have to consider a number of criteria related mainly to cost, the long-term performance of materials, the environment of the road, and user comfort. The Walloon Ministry of Infrastructure and Transport (MET) has formed a working group to develop a method to assist contract-managing engineers in this choice. The model developed is based on multi-attribute utility theory (MAUT). The method requires, on the one hand, the construction of utility functions that “recode” the raw evaluations of alternatives for each of the criteria and, on the other, the determination of substitution rates that, as it were, represent the relative “weights” of the criteria. The development of the model was complicated by its “multi-decision-maker” nature. The model was validated on several practical cases. In addition, it was implemented so as to offer road managers a user-friendly user interface.