Optimal allocation of resources to maintain, rehabilitate, and reconstruct heterogeneous bridge networks

Highway bridges undergo rapid deterioration in both condition and safety under the influence of aggressive environmental factors and increasing traffic loads. Timely and adequate maintenance interventions therefore are crucial to ensure the functionality of bridges in a network. Under budget constraints, it is important to prioritize the maintenance of those bridges most significant to the functionality of the entire network. In this paper, the problem of network-level bridge maintenance planning is formulated as a combinatorial optimization problem. An algorithm is devised to select and allocate maintenance interventions of different types to networked bridges over a specified time under the assumption of annual inspections. The objective function considered was the network probability of failure, expressed by the time-dependent reliability of connectivity between the origin and the destination location, which was maximized while total maintenance costs were constrained under a budget. Various maintenance actions, which differed in unit cost and their effects on bridge performance, were used in the optimization. As an example, the optimization procedure was applied to a heterogeneous, five-bridge network. The proposed maintenance planning procedure can prioritize scarce maintenance needs for use on the deteriorating bridges most crucial to network performance.