Risk Assessment for STPA with FMEA Technique

Abstract

Failure Mode and Effect Analysis (FMEA) is a traditional technique for systematically analyzing cause and consequence relations between component faults and potential hazards during the system life cycle. Nevertheless, in the context of complexity of modern systems, FMEA is weak for dealing with interactions of system components. System Theoretic Process Analysis (STPA) seems to be born to handle the interaction of components. However, usual STPA does not focus on assessing risks—an important step in safety analysis. This paper presents a method which integrates risk assessment into STPA process by using FMEA technique. The proposed method will improve STPA in terms of evaluating risk level. More safety constraints also could be generated in component levels during analysis. We applied the proposed method in the case study of railway level crossing system and as a result it makes STPA more comprehensive in a safety analysis.