HS2 has marked a major milestone with the final breakthrough of the Bromford tunnel in Birmingham, completing all major tunnelling works between London’s Old Oak Common and Birmingham Curzon Street.

The Herrenknecht TBM “Elizabeth”, launched from Water Orton in March 2024, arrived at Washwood Heath, joining its twin “Mary Ann,” which completed its drive earlier this year. Together, the two 1,600-tonne TBMs excavated 5.6 km of twin tunnels, removing over 1.8 million tonnes of Mercia Mudstone and installing 5,804 concrete ring segments. The excavated material is being reused for landscaping around the railway.

This breakthrough means 44.8 km of deep-bore tunnelling between London and Birmingham is now complete. Work will now shift to internal concrete lining, walkways, cross passages, and ventilation shafts.

In total, eight TBMs have so far excavated 9.4 million tonnes of material for HS2’s tunnels, including the 16 km Chiltern and 13.4 km Northolt tunnels. Two additional TBMs are expected to launch next year for drives toward London Euston, while other sections include cut-and-cover tunnels in several rural areas.

Following the breakthrough, TBM Elizabeth will be dismantled, and work will continue on concrete finishing, base slabs, and safety walkways. The Washwood Heath site will eventually become HS2’s Depot and Network Integrated Control Centre, serving as the operational hub for the high-speed network.

HS2 leaders described the achievement as a “historic moment” and a testament to the engineering, planning, and teamwork behind the UK’s largest infrastructure project.

GZ provided Cat 3 Design check services for the tunnels and ancillary structures such as adits, cross passages and ventilation structures.

To read more about GZ’s involvement in the HS2 Project, visit our project page.

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Footage shows the HS2’s final Birmingham tunnel breakthrough (Copyright of the footage holds HS2).