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Our investment in the railway’s ‘traffic light system’ will replace outdated signalling systems and improve reliability and safety for passengers.

The traditional approach to signalling is to use trackside signals to control the safe movement of trains. But with our network under growing pressure to meet capacity needs, the changes we’re making to an ageing signalling system are an essential part of our vision for a better railway.

Creating a new legacy for the railway

Our investment in introducing the latest signalling and control technology is part of the European Train Control System (ETCS) and traffic management programme.

About the digital railway

Moving to the ETCS will allow trains to run closer together and travel at their best speeds while maintaining safe braking distances. Alongside the traffic management programme, we’ll greatly increase the capacity on our network by maximising the throughput that our existing track can support.

These future signalling technologies will mean more capacity, greater reliability and a safer network for all – fundamentally transforming the way that we operate the railway in the future.

How we’re doing it

We’re replacing trackside signalling equipment with modern, in-cab computer displays and control centre systems, which means the future of railway signalling belongs inside the train, bringing all information from one of 12 regional operating centres around Britain to the driver, instantly.

Across Britain, we’re carrying out the complex electrical work needed to ‘recontrol’ the signals, which involves moving control of the signals from the side of the track to new, state-of-the-art operating centres.


In 2016 we completed a number of resignalling projects, including over May Day bank holiday in the Rotherham, Swinton and Mexborough areas, moving control from the Sheffield power signal box to the new York rail operating centre.

Over the same holiday we finished resignalling between Balham and Streatham, with the new brighter, more reliable and energy-efficient signals switched on and control moved to the rail operating centre in Three Bridges, Sussex.

Resignalling also took place around the Filton area of Bristol, with control moved to the state-of-the-art Thames Valley signalling centre in Didcot.

Project close-up: Cardiff Area Signalling Renewal (CASR)

Part of a wider £450m scheme to modernise the railway in South Wales – the biggest investment in the Welsh network for more than 100 years – CASR will help to reduce congestion and deliver a more reliable railway across the Cardiff and Valleys network. Work on the signalling renewals scheme started in 2013 and was commissioned in January 2017.

Passenger benefits

Improved signalling technology means more reliable journeys with fewer delays, so more trains can run and more people will be able to travel on the railway across South Wales.

Modernising the railway in Wales helps pave the way for electrification so that faster, longer, greener and quieter trains can run between London and Cardiff – making it easier and quicker for commuters in South Wales to get to and from work. Faster journey times could also benefit businesses in London looking to relocate or set up new bases in the area – a boost for the local economy.

What’s involved

There were five major phases of the CASR project: at Vale of Glamorgan, Valleys, Barry, East of Cardiff and West of Cardiff & Cardiff Central.

The signalling was recontrolled to the Wales Railway Operations Centre (ROC) and new signalling equipment installed along the railway in the area.

CASR has also delivered new track, station enhancements and new platforms at Cardiff Central, Cardiff Queen Street, Barry and Caerphilly. Overhead gantries were erected and switches and crossing points renewed.

CASR at a glance

  • More than 5,500 people worked on the project
  • More than 4m hours worked
  • 192 miles
  • 5 phases
  • More than 830 wheel sensors fitted
  • 370 new signals installed
  • 100 sets of points installed, renewed or recontrolled
  • 12 to 16 trains per hour through Cardiff Central station
  • 6 new platforms (Tirphil, Caerphilly, Queen St x2, Central and Barry)
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