Northern Line Extension Tunnelling Giants Positioned
A major milestone in the construction of the Northern Line Extension was reached recently with the lowering of two giant tunnel boring machines 20 metres below ground in Battersea, London.
The lift was carried out using a 750 tonne Liebherr LR1750 crawler crane. 35 lorry loads delivered the enormous crane.
The first delivery arrived on Monday 6 February, upon which assembly began.
A test lift took place prior to lowering each of the two tunnel boring machines, Helen and Amy, in the shadow of the iconic Battersea Power Station.
The TBMs were each lowered into the ground perpendicular to the direction they will be tunnelling in as a result of the constraints placed by the props running along the crossover box.
Following this, each TBM was rotated 90 degrees to line up with the launch rails and then jacked into the launch tunnels.
After the first lift, the crane was relocated and reloaded to facilitate the second lift. It was a challenge to manoeuvre the 750 tonne crane due to space constraints. Following this, reloading the ballast, or steel weights placed at the rear of the crane to provide stability, in such a tight time scale was a testament to the expertise of our team members involved.
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