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Neil Popplewell

BEng (Hons) Computer & Electronic (1st Class) PGDip Railway Signalling and Telecommunications Member of the Institution of Railway Signalling Engineers (MIRSE)

Rail Control Systems Australia

Safe communication of information between railway signalling systems has always been an essential part of signalling system design. This has primarily been driven by the need to safely and accurately communicate the state of the railway to the various subsystems and end users of the system, over typically very large geographical distances imposed by the topology of railway networks.

This paper explores and compares the benefits, suitability and required application considerations of the various communication methods used for signalling systems, with a focus on modern, safe, software based communication protocols that support transmission over open networks. This analysis extends to considerations relating to the communication bearer, the effect of the network layers above and below the protocols’ safety layers, latency, redundancy, encryption, reliability and availability, and the suitability of certain types of protocols for various applications.

The paper also includes a case study of the implementation of the Frauscher Safe Ethernet (FSE) protocol on the HIMA safety controller. It includes discussion relating to the design and testing techniques that were employed, the methods followed to ensure compliance with relevant industry safety standards, and the outcomes and benefits resulting from the implementation.