Theory of Safety-Related Violations of System Barriers

This paper focuses on a theory of the safety-related violations that occur in practice during normal operational conditions, but that are not taken into account during risk analysis. The safety-related violations are so-called barrier crossings. A barrier crossing is associated to an operational risk which constitutes a combination of costs: the cost of crossing the barrier, the benefit (negative cost) immediately after crossing the barrier, and a possible deficit (extreme cost) due to the exposure to hazardous conditions that are created after the barrier has been crossed. A utility function is discussed which describes the consequence-driven behaviour and uses an assessment of these costs functions. An industrial case study illustrates the application of the proposed theory.