Towards a Common Ontology of Safety Risk Concepts for Railway Vehicles and Signaling

Abstract

In the railway domain, different methods are applied for estimating safety targets (like SIL) in the subdomains of railway rolling stock (e.g., SIRF) and railway control, command and signaling (e.g., BP-Risk), respectively, which are referred to as railway vehicles and railway signaling for the rest of this paper. Such methods are also based on different terminology underlying different concepts used, e.g., as parameters. Even worse, similar terms often mean different concepts. This may lead to different risk estimates for these subdomains of the railway domain.

Our approach for addressing these problems has been to create a common safety ontology covering the important concepts of both subdomains. Hence, we analyzed the methods SIRF and BP-Risk with regard to the terms and parameters used. Based on this analysis and a previous safety ontology for railway vehicles, we created a new common ontology for railway vehicles and signaling. It is also consistent with the related terminology of EN 50126 (for railway systems) and ISO 26262 (for automobiles). Such an ontology should facilitate the reuse of hazard and risk analyses from one subdomain to the other, and it should have important application areas such as estimating safety targets consistently.