Critical Infrastructure Interdependence

Critical infrastructure comprises all the assets that are vital for the smooth functioning of a society. They include infrastructures such as energy, communications, healthcare, transportation and others. These critical infrastructures are coupled in various ways, and, therefore highly interdependent.

Critical infrastructure (CI) comprises all the assets that are vital for the smooth functioning of a society, i.e. health, safety, economy and social well-being. A distinction can be made between different sectors, such as energy, which includes electricity supply and heating, communications, healthcare, transportation, water supply, security services, agriculture, critical manufacturing and finance. These infrastructures largely depend upon each other. According to [1], these interdependencies can be classified into four classes:

1. Logical interdependencies – refer to interdependent decision-making of the infrastructure management and control systems.
2. Cyber interdependencies – refer to the coupling of control systems via suitable communication channels.
3. Physical interdependencies – refer to connections through the infrastructure itself, e.g. transmission lines and pipes.
4. Geographic interdependencies – relate to the exposure to failures of infrastructure assets due to their locations, e.g. proximity.

As an example of these interdependencies, a pro-longed large-scale power outage can severely disrupt other sectors through physical dependence, i.e. electricity is needed to maintain other infrastructures such as communications and water supply. Many services in turn rely upon functioning communication channels. Interruption of communication can also severely limit the ability to mitigate failures within other CIs, i.e. it hinders response, coordination and recovery. This interdependence corresponds to the cyber interdependence class. In this scenario, a logical interdependence may occur in case of conflicting decisions such as prioritization of resource deployment, e.g. deployment of emergency response teams.

As this example illustrates, the consequences of failures may well extend beyond the infrastructure directly affected. Thus, it is imperative to study the CI interdependencies to understand the dynamics of this system of systems, to implement preventive methods and to design response and recovery strategies that can ultimately improve the resilience of the system.

To support these efforts, the PHOENIX project has joined the European Cluster for Securing Critical Infrastructures (ECSCI), which is a coalition of European Horizon 2020 projects dealing with both physical and cybersecurity of CIs. Each project focuses on different aspects of CI security and the related sectors involved such as energy, healthcare, finance, communication, gas and water, and transportation. ECSCI provides a platform to exchange technical approaches and ideas and to form synergies among the participating projects. Moreover, within this context, ECSCI facilitates investigating cross-sector interdependencies and cascading effects and enables the creation of a holistic perspective on Europe’s critical infrastructure.

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[1] Lewis, L. P. and Petit, F. Critical infrastructure interdependency analysis: Operationalising resilience strategies. Contributing Paper to GAR 2019