A 750-tonne capacity Liebherr LR1750, owned by Weldex, lowered the TBMs 20 metres below ground in Battersea this week, from where they will drive 3.2km to the existing Northern Line at Kennington.
Main contractor is Ferrovial Agroman Laing O'Rourke joint venture, which goes by the abbreviated name of Flo.
Tunnelling will take six months to complete. When the whole project is completed, expected in 2020, the Charing Cross branch of the Northern line will extendfrom Kennington to a new station at Battersea Power Station, via a new station at Nine Elms.
The TBMs have been named Helen and Amy, after astronaut Helen Sharman and aviation pioneer Amy Johnson. Both TBMs will now be fully assembled within two 77-metre long launch tunnels, before starting their journeys towards Kennington next month. When fully assembled, Helen and Amy will each be 100 metres in length.
After both tunnel boring machines and their gantries are constructed, a conveyor system will be built to take the spoil from the tunnels up to barges on the River Thames. More than 300,000 tonnes of earth will be excavated and spoil will be taken to Goshems Farm in East Tilbury by river where it will be used to create arable farmland.
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