Novel Online Safety Observer for Railway Interlocking System

Abstract

Due to the complexity and size of railway interlocking systems, conventional verification and testing techniques are not able to provide sufficient safety assurance. This paper proposes an online observer for safety assurance of railway interlocking systems. The observer provides runtime checking of the states and behaviors of interlocking devices by using a topology-based mathematical model. Route signals, points, and track sections are interpreted in a topological space, and safety properties are expressed as topology theorems. Running synchronously with the interlocking task, the observer conducts safety checks on the route processes and point operations. A case study of an example Chinese railway interlocking system is presented to illustrate the proposed method and its strengths. It is anticipated that this method will provide a fresh means to verify safety properties of railway interlocking systems in addition to traditional testing and verification methods.