Infrastructure disruption caused by natural hazards is a reality for transportation networks and might become even more important with an increase of such incidents due to climate change. To maintain the network efficiently, infrastructure management systems (IMS) have been developed which determine optimal maintenance and improvement strategies for infrastructure components but they are not designed to integrate aspects of vulnerability. This study presents a framework on how vulnerability can be quantitativelyintegrated in the management of large road infrastructure networks and applies the methodology to the Swiss case. The project is carried out in twoparallel streams. The first part identified hazard scenarios bringing together information about network components and natural hazard potential. The second part quantifies the additional user cost caused by a given hazard scenario. For intensely used road networks in densely populated countries, like Switzerland, a reliable assessment of the additional user costs has to be based on traffic assignments which consider congestion effects. Asthe duration of most failures is assumed to be less than two weeks no effect on travel demand is considered. Mode choice effects are also neglectedas those are assumed to be small over the network as a whole. A further constraint was that the hazardous network component assessment was carried out parallel to the stream reported here. Therefore, at the beginning of the project it is not clear which links are endangered. However, with the special topography of Switzerland it can be assumed that large parts of thenetwork might be affected. So, it was decided that the methodology to be applied must be able to deliver estimates of the consequences of failure for all links in the national road transport model, which covers all main roads. The national road transport model for Switzerland consists of around20'000 links whose separate failures represent a case each. Given a calculation time of 50 minutes to reach equilibrium, full network assignments for all cases is unrealistic. Therefore an alternative approach was developed and validated. Analyses of full assignments showed that in most cases the effects of link failures are spatially restricted. The study shows under what circumstances the application of sub-networks covering only a certain buffer around the affected link is appropriate, the accuracy that mightbe expected from such an approach and the optimal sub-network size dependent on the local network topography and population and employment density respectively. Moreover, a statistical model is presented which enables authorities to estimate additional user costs caused by link failures withoutrunning an assignment model. This might be the case in developing countries where only information about the network, such as topology and traffic counts is readily available. The statistical model employs state-of-the-art methods accounting for spatial error and correlation effects and builds on earlier models predicting link speeds. For the covering abstract see ITRD E145999
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