An OPC UA-based subject-oriented information model of railway signalling assets as a way of reducing configuration complexity and improving functional safety

Abstract

The paper addresses the problem of integrating computer-based railway signalling systems with supervisory control and data acquisition (SCADA) systems. Conventional network protocols with flat memory addressing create a semantic gap between physical equipment and traffic control abstractions, which exponentially increases the algorithmic complexity of configuration and diminishes cyber-physical security. The aim of the study is to develop a domain-specific information model for basic trackside assets (railway switch, route section, signal) based on the IEC 62541 (OPC UA) standard. The paper proposes a method for encapsulating the fail-safe interlocking logic directly into the protocol’s network stack using software calls (methods) and dynamic management of the execution permission system attribute. It is mathematically proven that applying property inheritance and machine selfdescription mechanisms allows reducing the algorithmic complexity of operator workstation configuration from a linear-multiplicative dimension of O(N×M) to O(N). The findings confirm an improved system protection against logical attacks and operator errors. The proposed data type hierarchy can serve as a prototype for creating a single industry specification for the interaction of railway signalling systems.