Comparative Analysis of STPA and FRAM: The Effect of Process Delays for Enhanced Safety and Resilience

Abstract

Understanding process delays can be significant for implementing effective long-term resilience enhancing measures. And looking into those delays also helps understanding the impact of unintended side-effects arising from short-term safety measures. To do that, this work compares the methods System Theoretic Process Analysis (STPA) and Functional Resonance Analysis Method (FRAM) in regard to the implementation and representation of process delays. STPA is a famous example for the combination of control engineering and safety science. It models system failures and successes involving complex dynamic processes. FRAM tackles the same problem from the opposite direction: it was created from the resilience community to analyse system processes. We apply the two methods to the same infrastructure model from the literature and focus especially on how the methods handle delays within processes.