The effect of including societal consequences for decisions on critical infrastructure vulnerability reductions

Critical infrastructures provide society with services that are essential for its functioning and extensive disruptions of these give rise to large societal consequences. Vulnerability analysis gives important decision information concerning improving their ability to withstand strains. To analyze vulnerabilities in infrastructures models for estimating consequences due to failures are needed. Consequences arising from a critical infrastructure disruption can be estimated from an infrastructural or a societal viewpoint. Most risk and vulnerability related studies of critical infrastructures, however, focus rather narrowly only on the direct infrastructural consequences, e.g. expressed as services not supplied. An integrated model, consisting of a physical model of a critical infrastructure the Swedish electric transmission system) and an inoperability input-output model to estimate societal consequences is used. The paper analyze and contrast how the two viewpoints may affect the decision of which vulnerability reducing measures to implement. Vulnerability reducing measures are implemented as addition of branches to the existing power system. The results show a relatively large difference when considering estimated effectiveness but the ranking of the measures is to some extent, congruent, however it is concluded that accounting for societal consequences in the decision-making process, when prioritizing between different vulnerability reducing measures, is of importance