Two giant tunnel boring machines lowered into place for Northern Line Extension

Credit: TfL

Two giant tunnel boring machines have been lowered 20 metres below ground in preparation for tunnelling work on the Northern Line Extension.

Credit: TfL

With tunnelling work due to commence on the Northern Line Extension in London during March 2017, two tunnel boring machines have been lowered into place below ground in Battersea by a 750-tonne crane.

‘Helen’ and ‘Amy’ tunnel boring machines will create two 3.2km underground tunnels

The tunnelling machines, named Helen and Amy, will create two 3.2km underground tunnels which will extend the Charing Cross branch of the Northern line from Kennington to Battersea Power Station, via Nine Elms Station. Tunnelling work is estimated to take six months to complete. The extension, targeted for completion in 2020, is the first major Tube line extension since the Jubilee line in the late 1990s.

Credit: TfL

According to Transport for London (TfL), both machines will now be fully assembled within two 77m long launch tunnels, before starting their journeys towards Kennington next month. When fully assembled, ‘Helen’ and ‘Amy’ will each be 100 metres in length.

Tube map of proposed extension. Credit: TfL

Once assembled, 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 taken to Goshems Farm in East Tilbury, Essex by boat where it will be used to create arable farmland.