Safety management – A multi-level control problem

• We apply the control metaphor to safety management and demonstrate how it can be used.
• We model four distinctly different systems, man, technology, organisation and information.
• Successful control relies on four conditions, a model, observability, controllability and a performance function.
• State space can be divided into, a region of safe states, a region of unsafe states and a region, where safety is undecided.
• Polycentric control can provide a path forward to better safety management.

Activities in safety management build on a control metaphor by which control loops are built into the man, technology, organisational and information (MTOI) systems to ensure a continued safety of the operated systems. In this paper we take a closer look on concepts of control theory to investigate their relationships with safety management. We argue that successful control relies on four necessary conditions, i.e. a system model, observability, controllability and a preference function. The control metaphor suggests a division of the state space of the modelled system into regions of safe and unsafe states. Models created for selected subsystems of the MTOI-system provide a focus for control design and safety assessments. Limitations in predicting system response place impediments to risk assessments, which suggest that new complementary approaches would be needed. We propose that polycentric control may provide a concept to consider in a search for a path forward. We investigate approaches for modelling management systems and safety management. In spite of promises in the use of a control metaphor for safety management there are still dilemmas that have to be solved case by case. As a conclusion we argue that the control metaphor provides useful insights in suggesting requirements on and designs of safety management systems. The paper draws on experience from the Vattenfall Safety Management Institute (SMI), which started its operation in 2006.