Balfour Beatty VINCI has marked a major milestone in the construction of HS2, as giant tunnel boring machine (TBM) Mary Ann completed her journey beneath the West Midlands, breaking through at Washwood Heath to finish the first bore of the 5.8km (3.5-mile) Bromford Tunnel.

The 125-metre-long TBM began work in July 2023, carving a subterranean path from Water Orton in Warwickshire to northeast Birmingham. Named Mary Ann by the local community in honour of Warwickshire-born novelist George Eliot, the machine's breakthrough is the first of its kind for HS2 in Birmingham.

Designed to significantly enhance rail capacity and connectivity, HS2 will almost halve journey times between London and Birmingham, while also freeing up space on the West Coast Main Line for additional regional and freight services.

The tunnel's construction was a formidable engineering feat, with a 450-strong team working in shifts over 22 months to guide the 1,600-tonne machine through complex and challenging ground conditions at depths of up to 40 metres. During the journey, Mary Ann passed beneath Park Hall Nature Reserve, the M6 motorway, and the River Tame—crossing the latter four times with just five metres of clearance.

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In total, Mary Ann excavated approximately one million tonnes of material, which is now being reused to support the construction of the nearby Delta Junction, a crucial connection point that will link HS2 to Solihull and Birmingham's Curzon Street Station. The use of dedicated haul roads for spoil removal minimised the impact on local traffic.

The tunnel itself was constructed using nearly 21,000 precision-engineered concrete segments produced at Balfour Beatty VINCI's pre-cast facility in Avonmouth. These segments formed 2,971 complete rings that now line the tunnel interior.

The Washwood Heath site, where Mary Ann emerged, will play a central role in HS2's future operations. Adjacent to the tunnel portal, the railway’s Depot and Network Integrated Control Centre will be built, becoming the hub for train servicing, storage, and real-time management.

Meanwhile, the second bore of the Bromford Tunnel is progressing and will be completed later this year by a second TBM named Elizabeth. Following excavation, crews will begin interior works including the installation of cross passages, concrete base slabs, and emergency walkways.

This phase of HS2's construction coincides with peak activity along the route, with around 31,000 people now working on the programme nationwide. The tunnelling team itself includes eleven apprentices, recruited and trained in collaboration with Solihull-based Rorcon and national tunnelling specialists Tunnelcraft, as part of a broader initiative to tackle the UK’s tunnelling skills shortage.