Assessing Response System Capabilities of Socio-technical Systems

Our society is becoming more and more dependent upon the reliable function of a number of vital socio-technical systems. These systems are often being referred to as critical infrastructures, or lifeline systems, indicating their importance for supporting a nation’s economy and social well-being. In the present paper a method is presented for assessing the capability of those actors involved in restoring socio-technical systems after strains affecting its technical systems. Parallel ongoing work by the authors, not presented here, emphasises on
technical systems’ interdependencies. Together, these approaches address the issue of vulnerability analysis of socio-technical systems. The presented method is derived from the theories of both systems thinking and resilience engineering. The method has been applied in a preliminary study of a socio-technical system, namely the Swedish railway system. The
method systematically identifies the system elements by evaluating the system both under normal operation and under strain. The actors directly involved in the restoration of the technical system, referred to as the response system, are identified and selected for in-depth studies. The overall objective of the study is to assess the time required for the response system to restore the technical system after strains of varying magnitude, by introducing the concept of response curves. The curves reveal response system capabilities and their limits, i.e. the magnitude of strain for which the actors can no longer cope. It is concluded that the proposed method is both applicable and valid in the efforts of assessing response system capabilities of socio-technical systems.