Application of the System-Theoretic Process Analysis (STPA) technique to enabling systems in the rail industry

Investigations into several recent railway safety incidents have concluded that failures of enabling systems contributed significantly to the root cause of those incidents, suggesting a tendency towards poor management of safety risk associated with subsystems outside the immediate System of Interest (SoI) boundary. This paper examines whether better application of systems thinking to the analysis of hazards, through use of the System-Theoretic Process Analysis (STPA) technique, could have enabled safety risk to be better identified and managed in the circumstances surrounding a serious derailment that occurred in Victoria, Australia in February 2020.