A quantitative approach for applied resilience assessment audits

Today’s infrastructural systems are expected to be safe and resilient. In this context, assessment of such systems faces two principal challenges: common approaches in risk assessment have reached their limits in methodology and feasibility in assessing complex and interconnected systems. On the other hand, resilience assessment is in its beginnings and lacks, e.g., a commonly accepted resilience metric. The paper starts to specify a practical definition of resilience and assigned metric: Resilience is characterised by influencing recovery properties of a socio-technical system. Actors and actions are carriers of these properties. This corresponds to the views of system representation by Use Case Diagrams (UCD). In order to quantify an UCD, actions are validated by assessing their compliance level L. Actors are associated with their abilities to respond, monitor, learning, and to anticipate developments. The result is given by the Resilience Priority Value REPV = L ⋅ I of actors and overall system. The resilience assessment process is exemplified by a case study of a car park guidance system