HS2 completes final Birmingham tunnel breakthrough
HS2 has celebrated a major construction milestone with the breakthrough of tunnel boring machine (TBM) Elizabeth in Birmingham — completing the final deep-bore tunnel between London’s Old Oak Common and Curzon Street in the West Midlands.
The 125-metre-long TBM was launched from Water Orton, Warwickshire, in March 2024 to excavate the 3.5-mile (5.6km) Bromford tunnel, which will carry high-speed trains beneath the M6 and the city’s eastern outskirts. Its twin machine, Mary Ann, completed the westbound bore earlier this year.
Together, the two TBMs — operated by Balfour Beatty VINCI (BBV) — have excavated 1.8 million tonnes of Mercia Mudstone and installed 5,804 precast concrete ring segments, forming the structural lining of both tunnels. The material removed is being reused for landscaping works along the railway approaches.
The milestone marks the completion of 28 miles of twin-bore tunnelling between Old Oak Common and Birmingham Curzon Street. Construction teams are now shifting focus to internal walkways, ventilation shafts and cross passages.
Alan Morris, HS2’s construction delivery director, said: “Today’s breakthrough is a major milestone for the tunnelling team here in Birmingham and for the HS2 project. All eight of the TBMs digging our tunnels between Old Oak Common and Curzon Street have now broken through. The focus is now on internal concrete work, ventilation shafts and cross passages. I’m immensely proud of the men and women who have worked round the clock to bring our TBMs and their crews home safely.”
Jules Arlaud, tunnelling director at Balfour Beatty VINCI, added: “This is BBV’s fourth and final TBM breakthrough, delivered by our expert tunnelling team who’ve worked around the clock over 19 months to arrive at this point. Guiding Elizabeth safely beneath the M6, key energy networks and the River Tame demonstrates the engineering precision and collaboration behind this achievement.”
Each of HS2’s eight TBMs operates as a self-contained factory, excavating, lining, and grouting concrete segments into place as it advances at around 10 metres per day. Across the route between London and Birmingham, the machines have collectively excavated 9.4 million tonnes of material, including through the 10-mile Chiltern tunnel and the 8.4-mile Northolt tunnel.
Once complete, HS2 will cut journey times between London and Birmingham to 49 minutes, free up capacity on the West Coast Main Line, and support new local and freight services.
At the breakthrough site in Washwood Heath, the Bromford tunnel portal will connect directly to HS2’s new Depot and Network Integrated Control Centre, which will manage and maintain the high-speed network. The depot is one of three major West Midlands sites driving regeneration around HS2’s new infrastructure — alongside Birmingham Curzon Street and Interchange Station in Solihull — forecast to add £10 billion to the regional economy over the next decade.
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