The History of Rail Signalling

Norman Hugill, Heritage Rail Consultant: “During the early years of rail, most lines were single-track with sidings approximately a mile apart. If two trains approached each other from opposite directions, the train nearest to the siding was expected to shunt aside to allow the other train to pass. This often led to conflicts between drivers, as neither wanted to yield.

As double tracks were introduced for trains travelling in opposite directions, time interval working was introduced, particularly in tunnels. When junctions were necessary, this marked the beginning of a true signalling system, which indicated the intended route for the train. In its earliest form, the system lacked interlocking mechanisms, and signals were often positioned above the signal box. Signalmen were known as policemen in the early days, and still occasionally, you may hear the signalman referred to as ‘Bobby’.

Signalling remains an evolving process, striving to keep pace with the modern world and technology. In some parts of the country, electric tokens for single lines, originally invented during the Victorian era, are still in use today, effectively carrying out their intended function.”

James Brownhill, Principal Consultant: “The railway industry can be slow to change. The first pilot of ETCS, on the Cambrian line, was completed over a decade ago, yet many lines still depend on semaphore signalling and local signal boxes. However, there is now a clear drive for innovation throughout the industry. With the anticipated increase in passenger and freight journeys, the need to complete upgrades cost-effectively, address the skills shortage, and support the UK’s environmental commitments, the industry cannot afford to remain stagnant.

To fully realise the benefits of technological advancements, the industry needs to collaborate more effectively. The establishment of Great British Railways (GBR) is a significant first step in this direction. We must work together to identify our common goals, determine the necessary changes to encourage innovation, and facilitate the adoption of new ideas, technologies, and processes.

ETCS Level 3 and moving block technology will enable better utilisation of existing infrastructure and eliminate much of the lineside infrastructure that requires construction and maintenance visits. Utilising real-time data to enhance performance and efficiency, such as through Traffic Management Systems that proactively plan and adapt timetables and Connected Driver Advisory Systems (C-DAS) that inform drivers of the optimal speed to conserve power and minimise heavy braking and acceleration, is likely to transform how we operate our trains.

Automated planning, assessment, design, integration, and testing tools, like Network Rail’s Synthetic Environment and Enterprise Architecture, will revolutionise the way we plan, develop, and deliver signalling projects. These tools will foster a more collaborative and holistic approach, optimising the use of resources within the industry to deliver effective solutions within budget and on schedule.”