Life-cycle social analysis of motorway bridges

User costs of a bridge are the costs incurred by the users of the bridge, which result from any construction and/or maintenance activity being performed in the bridge. Typically, these costs encompass the additional time lost due to incurred congestion, the additional costs of vehicle operation and the costs of additional accidents. Usually, such costs are not considered in the procedures leading to the formulation of strategies for bridge construction, maintenance and repair, despite their relevance in comparison with the costs incurred by the agency or owner of the bridge. Moreover, in a life-cycle perspective of a bridge, with a time span over 100 years, the quantification of user costs is affected by a large number of uncertainties. Therefore, it is the purpose of this paper to introduce a life-cycle analysis for the quantification of typical user costs, in a probabilistic approach. For this purpose, the analysis of a motorway bridge in Portugal is performed. The results of the case study demonstrate that user costs can be much more important than costs supported by the concessionaire, in a life-cycle perspective, and thus, a much higher importance should be given to these costs apart from the scientific community.