Estimation of failure costs of a bridge in Italy

The optimal maintenance strategy for aging bridges is one that minimizes the total cost to the community. For each bridge, this total cost is calculated as the sum of the costs of necessary interventions and of the damages resulting from exceeding limit states, multiplied by the probability of such exceedances. The most challenging and complex aspect of this calculation is estimating the damages, as numerous uncertainties are involved. These uncertainties, along with the variability of certain parameters, can significantly influence the results. Damages are typically divided into direct and indirect costs. Direct costs, such as rebuilding collapsed sections, addressing social consequences like injuries or fatalities, and dealing with environmental impacts, are relatively straightforward to calculate, but they tend to be less significant. On the other hand, indirect costs—such as disruptions to infrastructure and psychological effects—are harder to quantify but often have a much larger impact. By leveraging available research and learning from past accidents, we can better estimate these indirect costs. The economic and social consequences of many historical bridge failures are well-documented, allowing us to identify key factors that drive the costs and determine the true magnitude of different types of damage. This article offers valuable guidance for reliably estimating the failure costs of a typical bridge.