TBM Dorothy was launched on the second bore in November last year and completed the 1.6km journey in four months. It installed 791 concrete rings, each made from eight 2m-wide segments weighing up to 8 tonnes

After the first bore was completed in July 2022, Balfour Beatty Vinci (BBV) dismantled the 125m-long TBM and returned it to the north portal where it was reassembled for its second journey.

David Speight, HS2 Ltd’s delivery director for main works civils on Phase One, congratulated the BBV tunnelling team.

“This is a key moment in HS2’s operation in the Midlands, which is now reaching peak momentum with over 400 businesses in the region already winning work, and 9,000 jobs supported,” he said.

“We’re looking forward to celebrating more milestones as work gathers pace on key structures such as the Delta Junction viaducts, Birmingham Curzon Street station, Interchange station and Washwood Heath Depot, creating more opportunities for local businesses and people.”

Michael Dyke, chief executive officer for Balfour Beatty HS2 Major Projects, said the 400-strong project team deserved a special mention for safely delivering “this incredible feat of engineering”.

Over the next few weeks, the team will start dismantling the shield from the TBM, while the rest of the machine will be pulled back to the start of the tunnel and disassembled, ready for transportation to East Birmingham. It will be fitted with a new shield before starting a 5.6km tunnel bore in early 2024, between Water Orton in Warwickshire and Washwood Heath in Birmingham.