TfL have released a number of images showing the Tunnel Boring Machines (TBMs) for the Northern Line Extension. These were lifted into place at Ferrovial Agroman Laing O’Rourke’s TBM portal at Battersea earlier this month.

The images highlight that whilst this will be a different build (both in terms of scale and, to a certain extent, technique) to Crossrail, the overall approach and technology involved are broadly the same. Despite coming from a different supplier (NFM Technologies in France) for example, the TBMs themselves are strikingly similar to those built by Herrenknecht.

As is traditional, the two TBMs required for the Northern Line Extension, like the Crossrail ones, also bear female names. The first, Helen, is named for astronaut Helen Sharman. The second, Amy, is named for British aviation pioneer and WW2 pilot Amy Johnson. Indeed this is not Johnson’s only link to transport in London – the Hilton hotels at both Heathrow and Gatwick are named in her honour.

With both TBM heads now in place, their associated trains will be assembled and attached. The 2.5km dig will then begin in the summer and finish in early 2018. Again, as on Crossrail, the spoil will be removed by river – also to Essex where this time it will be used to create arable land.

A wider view of the portal site

Lifting in front of Battersea Power station

The lift in progress

From below during the lift

Heading beneath the surface

The associated TBM trains will be built and attached beneath ground

A side on view of the TBM head. Note the shallow depth in comparison to the Crossrail portal at Pudding Mill Lane