Engineers have begun assembling the two Herrenknecht TBMs that will dig the final 7.2km of underground high-speed railway – carrying HS2 trains into the heart of London. Each TBM will launch from an underground box at one end of the project’s Old Oak Common station and will take around one and a half years to reach the railway’s final southern terminus at London Euston.
The unveiling of the TBMs – the final set to be launched for the railway between London and the West Midlands – marks another significant milestone for HS2.
It comes on the day that Mark Wild joins HS2 Ltd as the company’s new chief executive. Mr Wild, former CEO of Crossrail, will help oversee the project’s transition from a major construction programme to a working railway, with a renewed focus on controlling costs.
Huw Edwards, Stations Delivery Director, HS2 Ltd, said: “We welcome the commitment from the government to build HS2 all the way to Euston and preparations to tunnel from Old Oak Common are now well underway.
“A terminus station for HS2 in the heart of the capital will provide a vital gateway for passengers travelling to and from the Midlands and North, and will undoubtedly lead to the transport-led regeneration of Euston – supporting growth in the local economy and creating thousands of new homes and jobs.”
The two 190m-long TBMs were and were transported to Old Oak Common in pieces before being reassembled on site. This summer, the HS2 team lifted the machines into the underground station box using a 750-tonne crane. They are now being reassembled at the eastern end of the station, ready to bore to Euston.
The cutterhead – optimised to cut through London clay – is 8.53m in diameter with the i.d. of the tunnel set to be 7.55m.
The TBMs will erect a pre-cast concrete segmental lining, grouting them into place before moving forward at an average speed of 16m per day.
HS2’s London tunnels contractor, Skanksa Costain STRABAG (SCS) joint venture, is leading construction of the twin-bored tunnel. In January 2024 the team completed a logistics tunnel from a nearby site at Atlas Road which will provide access for materials, and a route to remove the London Clay being excavated by the machine. It has also built two spray concrete-lined tunnels from which the TBMs will be launched eastwards towards Euston. Boring is expected to begin in 2025.
SCS is already well advanced with construction the Northolt tunnel – a separate structure running west out of Old Oak Common towards West Ruislip, outer London.
James Richardson, Managing Director, SCS JV, said, “We are delighted that the Government has given the green light to delivering HS2 through to Euston, ensuring the full benefits of the new railway are realised. Over the past two years, we have continued with critical activities to ensure that we can deliver the Euston Tunnel and approaches quickly, and at the lowest possible cost.
“We are also making excellent progress on the tunnelling between West Ruislip and Old Oak Common, with four TBMs in operation, and the works well over 50% complete.”
The machines will complete their journeys underground with the shield of the machine left to form part of the tunnel. The mechanical components of the TBMs will be pulled back through the 7.2km tunnel and disassembled.
The approach to Euston will be completed by sprayed concrete lined tunnels which will then transition into three tunnels, which will enable trains to be fed into and from platforms at Euston station.
Final plans for the future HS2 terminus station at Euston are still under review and HS2 Ltd is continuing to work with the Government and other stakeholders to design an affordable station design that can run HS2 services from London to the Midlands. Further details will be announced by the Government in due course.
Herrenknecht
Pioneering Underground Technologies - Herrenknecht AG is the technology and market leader in mechanized tunnelling. As the only company worldwide, Herrenknecht delivers cutting-edge tunnel boring machines for all ground conditions and in all diameters - ranging from 0.10 to 19 meters.
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