Accounting for traffic disturbance in road infrastructure management: Optimal maintenance and rehabilitation planning for the society

Maintaining a high level of network performance at minimal cost is a central objective for road infrastructure management. Going beyond agency costs, decisions must consider the economic and environmental impacts of maintenance and repairs strategies due to traffic delays on commuters and providers of goods and services. A dynamic programming model is presented to determine optimal management policies for current and proposed paradigms by selecting the best maintenance and rehabilitation activities at each time step over the time horizon given the concomitant and predicted states of the bridges within the network as well as predicted future origin-destination flows. The empirical analysis is demonstrated for a small network of three viaducts in an urban environment in Montréal, Canada. The incremental user costs due to interventions on the structures of the network are obtained through traffic simulations based on trip-survey data to evaluate travel delays for all possible combinations of concomitant partial or complete road closures. The results show that optimal infrastructure management strategies in space and time differ substantially depending on whether only agency costs are used, or if policies also reflect socio-economic goals (including sustainability). The main findings indicate that by including user costs in decision processes, significant reductions in user costs are achieved with minimal impact on operator costs, thus easily satisfying a cost/benefit criterion. The findings provide new evidence for policymakers that the optimal sequencing of interventions in time and space on a network can significantly reduce societal costs, sustainability objectives and environmental impacts.