Validation in Risk and Hazard Analysis in Safety-Critical Industries: Understanding Current Practices to Develop a Framework for STPA Validation

Abstract

In recent years, scholars have increasingly delved into the theoretical foundations and issues surrounding risk and safety science. However, validation has not received much explicit attention although it has been highlighted as an important focus theme. To contribute to closing this gap, this thesis first explores the current state of practice in risk and hazard analysis validation in both academic works and in the context of safety-critical industries. Two empirical research studies are performed to understand current validation practices, understand the extent to which validation takes place, to identify frequently used approaches, and to uncover challenges and directions for improvements. The findings suggest that validation is not a common practice among researchers, and a lack of clear guidance on how to perform validation makes it a challenging task for practitioners. Then, the thesis proposes a formal validation framework for the Systems-Theoretic Process Analysis technique (STPA). This technique is selected as it has been identified as one of the few techniques capable of capturing the tenets of a systems view on accident causation and because it has gained increasing popularity in recent years. The framework aims to support a systematic assessment of the analysis's comprehensiveness, accuracy, and credibility using 15 proposed tests. The framework is based on theoretical validation concepts in related fields of study. It is recognized that the proposed framework should be further tested to confirm its practical usefulness. This leads to the final issue addressed in this thesis. An evaluation of the proposed framework is accomplished through an interview-based study with STPA experts, who provide feedback on the individual tests comprising the framework and on its theoretical underpinnings. The experts appreciate the framework in that it provides clear guidance on how to validate each step of an STPA analysis systematically and find some additional theory-based tests interesting for consideration in practice. Additionally, the thesis provides a comprehensive discussion of future research directions for validation of risk and hazard analysis techniques, such as developing a modular framework with associated guidance, tailored to a specific practical context, and integrating the proposed framework into the overall process of risk and safety analysis.