HS2 has achieved another significant construction milestone after tunnelling teams broke through into the Old Oak Common station box in west London, completing two 360-metre mined tunnel sections and establishing a continuous underground connection towards the railway’s western London portal.
The achievement follows the excavation of approximately 100,000 tonnes of material and the installation of 30,000 cubic metres of sprayed concrete, bringing the project closer to connecting Old Oak Common with Birmingham Curzon Street.
Once operational, HS2 is expected to provide journey times of approximately 45 minutes between the two stations, more than doubling peak-time rail seating capacity between London and Birmingham.
Complex tunnelling operation completed
Construction of the twin tunnels began at HS2’s Victoria Road crossover box in May 2024.
Unlike the project’s longer tunnels, which have predominantly been excavated using tunnel boring machines, these sections were mined using conventional tunnel excavators through London clay.
The approach was required because of the tunnels’ changing geometry, with their width narrowing from two tracks to one between the crossover box and Old Oak Common station.
Following excavation, the tunnels were supported with sprayed concrete before receiving a permanent cast in situ concrete lining using travelling formwork.
The breakthroughs involved an innovative technique in which sections of the dividing wall were cut into blocks and pushed backwards into the completed tunnels from the station side.
The northbound tunnel breakthrough took place on 13 October, with the latest achievement completing the connection.
All excavated material has been transported for reuse elsewhere in the UK.
David Hannon, Operations Managing Director at Skanska Costain STRABAG, said: “Our breakthrough into the Old Oak Common station box is a significant milestone for the project.
“This achievement is a credit to the teamwork and dedication of everyone involved, from those working deep underground to those supporting on the surface. We will continue to deliver our work with safety and productivity at the heart of everything we do.”
HS2 targets Birmingham opening by 2037
The completed sections create a continuous 8.8-mile tunnel connection between Old Oak Common and the West Ruislip portal.
HS2 reports that all deep-bore tunnelling between London and Birmingham is now complete, with more than 80% of major structures either under construction or finished.
During 2025/26, HS2 Ltd delivered more than 10% more construction work than planned and achieved six major milestones ahead of schedule.
HS2 Ltd Chief Executive Mark Wild said: “I pay tribute to all those who achieved, and safely delivered, the breakthrough into the Old Oak Common station box. This is a key milestone for the HS2 programme and helps bring us a step closer to achieving our challenging ambition of delivering the railway from Old Oak Common to Birmingham Curzon Street by 2037, or earlier.
“We are now in the final stages of a fundamental reset of the entire HS2 programme to deliver the line safely and efficiently between London the West Midlands at the lowest reasonable cost. The prize of our endeavour will be a new high-speed railway for the Great British Railways network, delivering much needed capacity and driving local regeneration. The new HS2 station at Old Oak Common is set to boost the local economy by £10 billion over the next decade.”
Euston tunnelling continues
Meanwhile, two tunnel boring machines launched from Old Oak Common in early 2026 are progressing towards Euston, excavating separate 4.5-mile tunnels.
Both machines are expected to reach their destination in mid-2027.
Rail Minister Lord Hendy said: “This is a major milestone for HS2, bringing us a step closer to delivering a world-class transport hub at Old Oak Common and connecting London to Britain’s new high-speed railway.
“HS2 will provide much-needed rail capacity, create space for more reliable services across the wider network and help unlock economic growth, homes and jobs in west London, the West Midlands and beyond.”
Old Oak Common will become a major interchange between HS2, Great Western Railway, the Elizabeth line and Heathrow Express.
The latest breakthrough represents further progress towards completing the railway’s London infrastructure, although significant construction, systems installation, testing and commissioning work remains before passenger services can begin.
