Evaluation of Projects for Rehabilitation of Highway Bridges

Abstract

This paper presents a decision‐support system for selecting the best set of strategies (projects) for bridge rehabilitation and replacement on a highway network, specifically during a long‐range planning of the bridge funding needs for budgeting and legislative purposes. The proposed methodology recognizes the following aspects of the decision problem faced by the bridge engineer: (1) Multiple‐attribute nature of bridge deficiencies; (2) risk impact of the predicted deterioration of the bridge; and (3) uncertainty due to the subjectively estimated decision variables. Based on a systems approach, the decision theory concepts of multiple criteria decision making (MCDM), utility theory, and decision making under risk (DMUR) are applied in formulating a decision‐support system, with the estimates of the decision variables represented as fuzzy numbers. Modeling the predicted deteriorated state (condition) of the bridge as state fuzzy probability vectors, the feasible strategies for bridge rehabilitation and replacement are evaluated under each probable state of the bridge. The evaluation of projects at each bridge site is based on the possibility distributions of the expected fuzzy utilities, which are computed as a benefit index of each feasible strategy. An example application is also described to illustrate the application of this decision‐support system.