Balfour Beatty VINCI’s massive tunnel boring machine (TBM), Mary Ann, broke through today, marking the completion of the first bore of the Bromford Tunnel—set to become the longest railway tunnel in the West Midlands as part of the HS2 project.
The 125-metre-long TBM launched in July 2023 from Water Orton in Warwickshire, driving 3.5 miles (5.8 km) underground to Washwood Heath in Birmingham. Named by the local community in honor of Warwickshire-born author George Eliot, Mary Ann is the first TBM to reach Birmingham on the HS2 route.
This breakthrough represents a major milestone for HS2, which aims to slash journey times between London and Birmingham while easing congestion on the West Coast Main Line by freeing up capacity for local, regional, and freight services.
The tunnelling feat was achieved by a 450-person team working around the clock over 22 months. Navigating depths of up to 40 metres, the crew expertly steered the 1,600-tonne TBM beneath challenging infrastructure including the Park Hall Nature Reserve, the M6 motorway, and the River Tame—crossed four times with minimal clearance.
HS2’s Washwood Heath site, where Mary Ann broke through, will soon host the project’s Depot and Network Integrated Control Centre, becoming the operational hub of the railway. Trains will be maintained and controlled from this facility using cutting-edge digital systems.
Jules Arlaud, Tunnelling Director at Balfour Beatty VINCI, praised the team’s accomplishment:
“Today’s breakthrough marks a proud moment for our team after navigating complex ground and live infrastructure. It reflects years of meticulous planning and collaboration with HS2 and our partners.”
Mark Wild, CEO of HS2 Ltd, added:
“This is a major milestone. The transformation at Washwood Heath will be central to HS2’s future operations, and the benefits are already rippling through the region with £10 billion of investment set to accelerate further.”
During excavation, Mary Ann removed approximately one million tonnes of spoil. In line with HS2’s environmental strategy, the material is being reused at the nearby Delta Junction construction site. Dedicated haul roads are used to limit disruption to public highways.
At peak performance, the TBM advanced about 30 metres per day. The machine simultaneously installed 20,797 concrete segments—manufactured in Avonmouth—to form 2,971 tunnel rings, each segment weighing up to seven tonnes.
The tunnelling team included eleven local apprentices trained in partnership with Solihull-based Rorcon and tunnelling specialists Tunnelcraft, addressing the national shortage of skilled tunnellers and helping build the next generation of infrastructure professionals.
Across the West Midlands, HS2 is driving economic growth and job creation. Around 10,000 people are working on the project regionally, including over 700 apprentices and nearly 2,000 individuals who were previously unemployed. Over 400 local firms are engaged in HS2’s extensive supply chain.
Alongside the tunnel, two new stations in Birmingham and Solihull, and associated development at Washwood Heath, are attracting significant private investment. The region is projected to see a £10 billion economic uplift over the next decade.
Meanwhile, the second bore of the tunnel is underway, led by TBM Elizabeth, with completion expected later this year.
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- Balfour Beatty is a leading international infrastructure group with over 27,000 employees driving the delivery of powerful new solutions, shaping thinking, creating skylines and inspiring a new generation of talent to be the change-makers of tomorrow.
- We finance, develop, build, maintain and operate the increasingly complex and critical infrastructure that supports national economies and deliver projects at the heart of local communities.
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