Optimal network-level bridge maintenance planning based on minimum expected cost

The goal of bridge management is to determine and implement the best possible strategy that ensures an adequate level of safety at the lowest possible life-cycle cost. Although this is generally recognized, the integration of life-cycle cost analysis with bridge reliability analysis has been very limited. Moreover, this has been formulated and illustrated only for individual bridges. A framework for optimal network-level bridge maintenance planning based on minimum expected cost is presented. The goal is the minimization of the expected maintenance cost of a bridge stock with maintenance of the lifetime reliability of each bridge above an acceptable (target) level. The approach is illustrated for a stock of realistic highway bridges. Individual bridges in this stock have different ages, and their reliabilities are time dependent. The framework offers a rational basis for optimizing the resource allocation for management of a stock of gradually deteriorating bridges based on balancing life-cycle maintenance cost and lifetime reliability. This has important practical implications in the development of the optimal management strategy for the bridge stock.