Systems-Theoretic Likelihood and Severity Analysis for Safety and Security Co-engineering

Abstract

A number of methodologies and techniques have been proposed to integrate safety and security in risk assessment, but there is an ideological divide between component-centric and systems-theoretic approaches. In this paper, we propose a new hybrid method for Systems-Theoretic Likelihood and Severity Analysis (STLSA), which combines desirable characteristics from both schools of thought. Specifically, STLSA focuses on functional control actions in the system, including humans-in-the-loop, but incorporates semi-quantitative risk assessment based on existing industry practice. We demonstrate this new approach using the case study of train braking control.