Using Portfolio Decision Analysis to Select Reinforcement Actions in Infrastructure Networks

Critical infrastructure networks, such as railway networks, provide essential services whose continuity must be secured. Towards this end, we combine multi-criteria portfolio decision analysis with Probabilistic Risk Assessment (PRA) to construct portfolios of reinforcement actions that contribute cost-efficiently to the attainment of objectives that represent the network's services. Our model admits a range of assumptions about the relative importance of these objectives through incomplete information about the weights associated with the corresponding criteria. It also helps identify which portfolios of reinforcement actions perform best with regard to these objectives at different budget levels. We illustrate our model with a study on the reinforcement of switches at a railway station, which connects several origin-destination pairs with different volumes of planned traffic. If one or more switches are disrupted, some connections may be lost, and the corresponding traffic volume will be affected. We formulate an additive multi-criteria utility function such that the weight of each criterion reflects the planned traffic volume for the corresponding connection. PRA algorithms are used to assess the reliability of these connections. The results help identify the switches where the reinforcement actions should be implemented when the aim is to maximize the station's performance, as measured by the expected enabled traffic volume between the origin-destination pairs.

Keywords: Probabilistic risk assessment, Multi-criteria decision analysis, Portfolio decision analysis, Infrastructure networks, Transportation systems.