Abstract
The proper functioning of critical infrastructures is crucial to societal well-being. However, critical infrastructures are not isolated, but instead are tightly coupled, creating a complex system of interconnected infrastructures. Dependencies between critical infrastructures can cause a failure to propagate from one critical infrastructure to other critical infrastructures, aggravating and prolonging the societal impact. For this reason, critical infrastructure operatorsmust understand the complexity of critical infrastructures and the effects of critical infrastructure dependencies. However, a major problem is posed by the fact that detailed information about critical infrastructure dependencies is highly sensitive and is usually not publicly available. Moreover, except for a small number of holistic and dynamic research efforts, studies are limited to a few critical infrastructures and generally do not consider time- dependent behavior. This paper analyzes how a failed critical infrastructure that cannot deliver products and services impacts other critical infrastructures, and how a critical infrastructure is affected when another critical infrastructure fails. The approach involves a holistic analysis involving multiple critical infrastructures while incorporating a dynamic perspective based on the time period that a critical infrastructure is non-operational and how the impacts evolve over time. This holistic approach, which draws on the results of a survey of critical infrastructure experts from several countries, is intended to assist critical infrastructure operators in preparing for future crises.