The huge machine will be delivered to site and start work in 2028, building momentum on the project which started construction earlier this year. The new road is on track to open in the early to mid-2030s.
At 16.4 metres in diameter the machine will be the largest ever used in Europe, and the third largest ever in the world. It will dig two parallel tunnels, each more than twice the size of the existing tunnels at Dartford and big enough for three lanes of 70mph traffic.
The project will double road capacity across the Thames east of London to tackle the chronic congestion at Dartford, and unlock economic growth by creating a new trade route between the ports of the South East, the Midlands and the North.
Due to the machine’s size – 120 metres long and weighing over 5,000 tonnes – it will be delivered to site in segments by sea and carried up the Thames and delivered to the Port of Tilbury.
Lower Thames Crossing’s mission is not only to deliver much needed infrastructure, but also to deliver the “greenest” road, caring for the local communities, and driving out embodied carbon from its construction.
Despite being one of the world’s largest tunnels, it will have one of the smallest carbon footprints, as carbon emissions have been significantly reduced. Innovations such as using low carbon concrete to line the tunnel, and changing the design to build less, will help the Lower Thames Crossing be the first major infrastructure project to be carbon neutral in construction.
The 2.6-mile-long tunnel will be the longest road tunnel in the UK, with a tunnel chosen instead of a bridge to avoid impacts on local communities and protected important wetland bird habitats. The Lower Thames Crossing is designed to blend into the landscape with around 80% of the 14.3 mile route in the tunnel, a cutting, or behind an embankment.
Shaun Pidcock, Delivery Director, Lower Thames Crossing said: “We are working at pace and are on track to deliver Britain’s greenest road, driving down carbon emissions and protecting the environment as we do so. Choosing our partner to supply the giant tunnel boring machine means real progress on the project – and we’ll put it to work as soon as it arrives on site in 2028.”
The machine will be built in Germany by Herrenknecht, who made the machines used to create the Elizabeth Line, the Silvertown Tunnel, HS2 and the Thames Tideway tunnels. It will be bought and operated by the project’s Delivery Partner, Bouygues TP Murphy Joint Venture.
Didier Jacques, Tunnel Construction Director, Bouygues Travaux Publics Murphy Joint Venture said: “As delivery partners for the tunnels and approaches for the Lower Thames Crossing, we're proud to be leading the construction of the UK's longest road tunnel. In close collaboration with Herrenknecht, the team will now work on the detailed design development of the tunnel boring machine. Our focus remains steadfast: working at pace to reduce carbon emissions, pioneer innovative solutions and embed safety at every stage of construction.”
Frédéric Battistoni, Head of Project Management at Herrenknecht said: “The Lower Thames Crossing Tunnel Boring Machine will be the largest machine ever built at Herrenknecht’s headquarters in Germany and the largest Variable Density TBM ever. It will also be equipped with the largest accessible cutting wheel ever built by Herrenknecht. Incorporating several industry-first innovations, the machine has been designed to adapt to changing ground conditions while enhancing safety, efficiency and logistics during tunnelling operations. The machine will support the excavation of both tunnel drives through a planned U-turn configuration”.
It will be a variable density machine to dig through the water table and varying geologies, such as clay and chalk up to 60m below the Thames. It will be powered by electricity from renewable sources.
A single machine will be used to dig both tunnels to save money and reduce the project’s carbon footprint. The machine will begin tunnelling near the Port of Tilbury in Thurrock in 2028, before being turned around to create the second tunnel.
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