Integrating System-Theoretic Process Analysis and System Dynamics for Systemic Risk Analysis in Safety-Critical Systems

This paper presents a novel integration of System-Theoretic Process Analysis (STPA) and System Dynamics (SD) for hazard and resilience analysis in safety-critical infrastructure systems. The methodology is applied iteratively to assess the safety and continuity of a hospital’s oxygen supply system, a key element of critical health infrastructure, addressing both technical and managerial factors. STPA identifies unsafe interactions between system components, which are systematically translated into a system dynamics simulation model. This dynamic perspective allows for the exploration of how hazards evolve over time and how control strategies influence overall system resilience. Unlike previous conceptual approaches, this study applies the integrated framework to a real-world incident of oxygen supply failure. The model structure is derived from STPA artifacts and validated using expert input and incident data. Simulation experiments uncovered emergent risk patterns, such as alarm delays, staff stress, and insufficient training, that are not evident through STPA alone. These insights support targeted interventions, including enhanced drill frequency and resource allocation, to strengthen infrastructure resilience. By embedding dynamic simulation within the STPA framework, this research moves beyond static hazard identification to enable scenario-based testing and conditional estimation of system response to support risk-informed decision-making. The resulting methodology is traceable, repeatable, and adaptable, offering a practical and generalizable tool for systemic risk analysis in critical infrastructures.