Vulnerability Assessment of Bridges Exposed to Scour

To improve the allocation of funds for the maintenance and risk mitigation of transportation infrastructure, there is a dire need for a simplified, yet sufficiently accurate, methodology to estimate bridge vulnerability to scour. The methodology should make use of existing data and indicate the basic variables needed to assess the vulnerability of bridges located around a future expressway in southeastern Serbia. The first part of the paper discusses the identification of possible modes of bridge failure caused by scouring that depend on soil, structure, and river hydraulic properties. The degradation of soil parameters is assumed to be the main cause of bridge failure. The capacity of a bridge to withstand a certain amount of structural damage governs the direct and indirect costs attributable to bridge failure; the subsequent work zones related to rehabilitation reduce the performance of the whole network. In the second part of the paper, a simulation of the redistribution of traffic flows is described for several possible scenarios; the simulations use state-of-the-art software VISUM, which was developed for computer-aided transportation planning and analysis. The simulated scenarios include the partial and full closure of road links as a result of bridge failures. The simulations confirmed that the most significant contribution to indirect costs stems from the increase in the total travel time of all network users