Protection-interdiction-restoration for resilient multi-commodity networks

Interdependent critical infrastructure systems represent substantial financial investments and are vital to maintain a fundamental level of social and economic well-being, making them attractive targets for malevolent actors. Many of these infrastructure systems carry multiple products, each with unique needs and importance to different stakeholders. This work extends a tri-level protection-interdiction-restoration model from a single commodity to multiple commodities, solving the model with an integration of Benders' decomposition and set covering decomposition. We propose a method to limit unmet weighted demand across commodities, considering unique interdependencies between network components and commodity-specific capacity requirements. An optimal solution is found iteratively by alternately fixing protection and interdiction variables. This work is illustrated with a case study of interdependent Swedish power and multi-commodity railway systems. Results demonstrate the convergent behavior of the master and subproblems, the value of network hardening, and the non-uniform network recovery trajectory. For the case study, the railway system was more vulnerable to disruption than the power system, making it a more attractive target for both protection and interdiction. The components that were commonly selected as part of a protection or interdiction plan were generally the ones with the greatest demand for iron ore, a highly critical commodity.