Alstom has completed what it describes as its largest-ever single re-signalling project in the UK, delivering Stage 2 of the Cambridge Resignalling, Relock and Recontrol (C3R) programme for Network Rail following an intensive 11-day Christmas blockade.
The commissioning, carried out between Christmas Day 2025 and the morning of 5 January 2026, required a full possession of Cambridge station and surrounding routes around the southern English hub. More than 250 people worked on each shift across 23 shifts, totalling over 50,000 hours, as Alstom and its partners delivered a major overhaul of one of the East of England’s busiest rail hubs.
Stage 2 of the C3R project covered the resignalling, relocking and recontrol of the railway north of Cambridge station, through the area of the new Cambridge South station, and southwards to the boundaries at Great Chesterford and Foxton. As part of the works, the ageing NX entry-exit panel at Cambridge Powered Signal Box was switched off after more than 40 years in service and replaced with two modern Modular Control Systems.
Cambridge South
The works are a key enabling step for the new Cambridge South station, which is being built to serve the rapidly expanding Cambridge Biomedical Campus. Network Rail expects the campus to support 27,000 jobs by 2031, alongside around 4,000 new homes across the Cambridge Southern Fringe. The four-platform station is due to open in June 2026 and is planned around 1.8 million passengers, with all passing services operated by Greater Anglia, Great Northern, Thameslink and CrossCountry expected to call from day one.
Delivering that service pattern requires wider infrastructure and signalling upgrades between Cambridge station and Shepreth Branch Junction, including additional track loops and track remodelling. In total, Stage 2 touched more than 100 signals, 76 point machines and over 300 axle counter sections, delivering 323 signalled routes controlled from two new interlockings, alongside nine level crossing recontrols.
Could be upgraded to ETCS
The new signalling system is built around Alstom’s Smartlock 400 interlocking technology and its MCS Infinity control platform, which the company says will improve reliability and flexibility while providing a platform for future digital upgrades, including the deployment of ETCS. The system is also designed to support the planned opening of Cambridge South station later this year.
Network Rail’s senior portfolio manager for C3R, Darren Hay, said the successful completion of Stage 2 was a testament to the collaboration between Network Rail, Alstom, train operators and the wider supply chain, enabling the railway to be handed back to passengers on time following a complex commissioning. “We are proud to play a key role in transforming the Cambridge area for the benefit of passengers and operators alike,” said Emmanuel Henry, Digital and Integrated Systems Managing Director UK and Ireland at Alstom.
A £200 million investment
The Cambridge works form part of Network Rail’s £200 million investment to modernise signalling across the region, replacing equipment that in some cases had been in service for more than four decades. Alstom was awarded the £130 million design-and-delivery contract for the Cambridge re-signalling programme in 2022, the largest single award made under Network Rail’s Major Signalling Framework Agreement.
With Stage 2 now complete, Alstom will progress Stage 3 of the programme through 2026, covering further level crossing works and the recontrol of the Ely–Norwich route, before Stage 4 brings the Newmarket and Bury St Edmunds areas into use in 2027.