Balfour Beatty VINCI (BBV), the joint venture delivering major civil engineering works for HS2 in the Midlands, has achieved a historic milestone with the final breakthrough of the Bromford tunnels in Birmingham. The successful arrival of the 125-metre-long tunnel boring machine (TBM) Elizabeth marks the completion of all major tunnel excavation between London’s Old Oak Common and Birmingham Curzon Street, spanning 28 miles of deep-bore tunnelling across the heart of the UK.
This breakthrough represents not just a feat of engineering but a defining achievement in the digital construction and infrastructure delivery of HS2, the UK’s largest transport project and a cornerstone of national connectivity and economic growth.
A triumph of engineering and collaboration
Launched in March 2024 near the Warwickshire village of Water Orton, TBM Elizabeth completed her 3.5-mile journey to Washwood Heath, tunnelling under some of the most complex ground conditions in the country. Together with her twin TBM, Mary Ann, which broke through earlier this year, the machines have excavated more than 1.8 million tonnes of Mercia Mudstone, installing 5,804 concrete ring segments to form the twin tunnels that will soon carry high-speed trains into Birmingham.
The tunnelling journey beneath the M6 motorway, National Grid energy infrastructure, and the River Tame, crossed four times with a clearance of just five metres, showcases the precision and safety standards underpinning HS2’s engineering design.
Jules Arlaud, Tunnelling Director at Balfour Beatty VINCI, called the moment “historic,” crediting meticulous planning and cutting-edge technology: “This is Balfour Beatty VINCI’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. This marks the culmination of exceptional engineering, dedication, and collaboration.”
Digital construction driving precision and efficiency
Balfour Beatty VINCI’s success on HS2’s Birmingham approach is underpinned by its commitment to digital construction, BIM integration, and data-driven project management. Advanced Building Information Modelling (BIM) systems, digital twins, and real-time data analytics have played a central role in monitoring TBM progress, ensuring geotechnical accuracy, and coordinating logistics such as spoil management and segment delivery.
The project has demonstrated how digital engineering enhances productivity, minimises risk, and enables accurate decision-making in high-stakes infrastructure environments. Remote monitoring systems and digital dashboards provided engineers with a real-time view of TBM performance, pressure, and ground conditions, allowing for proactive interventions and reduced downtime.
The result is a model for how digital transformation in the construction sector can deliver complex, high-value infrastructure projects efficiently and safely.
Sustainable engineering and environmental stewardship
Excavation of the Bromford tunnels also aligns with HS2’s sustainability and circular economy goals. The 1.8 million tonnes of spoil generated, comprising various grades of Mercia Mudstone, are being reused locally to landscape railway embankments and create natural habitats along the Birmingham route.
This approach minimises waste and reduces carbon emissions associated with material transport, reflecting BBV’s commitment to low-carbon construction practices and the UK’s net zero infrastructure objectives.
The road ahead: from tunnelling to railway systems integration
With tunnelling now complete, focus shifts to internal concrete works, ventilation shafts, and cross passages that will connect the twin tunnels. These complex finishing works will prepare the route for the installation of HS2’s high-speed rail systems, track, power, and signalling.
Alan Morris, HS2 Ltd’s Construction Delivery Director, praised the achievement: “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 works, ventilation shafts, and cross passages. I’m immensely proud of the teams who have brought our TBMs home safely.”
At Washwood Heath, the site of the final breakthrough, HS2’s Depot and Network Integrated Control Centre will soon rise. From here, all HS2 trains entering Birmingham will be serviced, stored, and managed in real time. This site will become the operational heart of HS2 in the Midlands.
Economic regeneration and regional growth
Washwood Heath’s transformation is also catalysing major urban regeneration and property development across Birmingham and Solihull. Alongside new HS2 stations at Birmingham Curzon Street and Interchange (Solihull), the area is attracting billions in investment.
Forecasts suggest the three key HS2 sites in the West Midlands could add £10 billion to the regional economy over the next decade, unlocking opportunities for local businesses, supply chains, and skills development in the digital construction and civil engineering sectors.
A defining moment
The final breakthrough of the Birmingham tunnels marks a pivotal step in HS2’s journey, and a testament to the power of digital innovation, engineering excellence, and sustainable design in reshaping the UK’s transport future.
From BIM-enabled tunnelling operations to data-led project delivery, Balfour Beatty VINCI’s work on HS2 stands as a case study in how digital construction can redefine infrastructure performance, delivering safer, smarter, and more sustainable outcomes at scale.
As the UK continues its transition to a digitally enabled construction industry, milestones like this demonstrate not only what’s possible, but what’s next.
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