HS2 has once again begun tunnelling under London, launching its third TBM under the city. The 853m long, 6.2m i.d. tunnel won’t be used by HS2 trains, but instead will be used to deliver materials and remove spoil from the northern portal where HS2’s Euston twin bored tunnel will be constructed.
Engineers from HS2’s contractor, Skanska Costain STRABAG joint venture (SCS JV), launched the 847 tonne machine from the Atlas Road site in North Acton, from where it will build the tunnel to the Old Oak Common Station site. The tunnel drive will be completed in around six months, with the tunnel constructed using 4,264 concrete segments forming 533 tunnel rings. The segments, each weighing over 3 tonnes, have been produced by Pacadar in Kent.
The tunnel will be used to transport 8,010 tunnel segment rings to construct the Euston tunnel. The segment rings are being manufactured by STRABAG in Hartlepool and will never be transported by public road – utilising rail, and the logistics tunnel – all part of HS2’s commitment to sustainable construction.
A conveyor system will also run through the logistics tunnel, and will connect to an existing conveyor at Atlas Road, taking the London clay being excavated to construct the Euston Tunnel to HS2 London Logistics Hub at Willesden Euro Terminal. From there, the spoil will be taken by train for re-use at sites in Kent, Cambridgeshire and Rugby.
The TBM being used to construct the tunnel has been repurposed using components from TBM, ‘Ellie’, previously used on the Crossrail project. ‘Ellie’ bored two sections of the Crossrail tunnels in the Capital – from Limmo Peninsula in Canning Town to Royal Victoria Dock, and between Pudding Mill Lane and Stepney Green – boring a total 3.5km.
Herrenknecht has designed a TBM specifically for HS2’s requirements and has expertly remanufactured components including the shield and the cutting wheel.
The TBM was switched on following a naming and blessing ceremony at the Atlas Road site. Lydia was at the event to see her name unveiled on the giant machine, alongside pupils from Old Oak Primary School.
James Richardson, Managing Director of Skanska Costain STRABAG JV, said:
”This is our third TBM to launch in London and later this year we will have five machines operating. Four of these will be boring the HS2 tunnels, linking West Ruislip and Old Common. Today’s launch is significant as it is not used for the operational railways, but will create a direct link to between our logistics hub and Old Oak Common, allowing us to transport tunnel segments and spoil without using local roads.”