Northern Line
Tunnel Boring Machine breaks through at Kennington to complete tunnelling for LU’s Northern Line extension.
Tunnelling on the Northern Line extension was completed on November 8, when Tunnel Boring Machine Amy broke through at Kennington. The first TBM, Helen, had broken through earlier this month.
Two 1.98-mile tunnels have been built from Battersea to Kennington, via Nine Elms. The extension is due to be completed in 2020 and will bring Battersea to within 15 minutes of the City and the West End. It’s also designed to enable regeneration of Vauxhall, Nine Elms and Battersea - Transport for London says that when the extension is open the line will support some 25,000 jobs and more than 20,000 new homes.
Construction of new stations at Battersea and Nine Elms is also progressing, says TfL.
The two tunnels measure 5.2 metres in diameter. The two TBMs could travel at up to 30 metres per day, with teams of around 50 operating them. Nearly 20,000 precast concrete segments were put in place to form rings to line the tunnels, while two junctions with iron rings will link the extension to the existing Northern Line.
Mike Brown MVO, London’s Transport Commissioner, said: “Both machines have had to navigate a challenging, congested path under south London which included sewers, power cables, a Victorian-era well, and existing Victoria and Northern Line tunnels. This achievement brings us a significant step closer to the delivery of the first major Tube extension in nearly two decades.”
TfL said the cutter head of both TBMs will be lifted by crane from the shafts while the rest of the machines will travel back to Battersea where they will be lifted in parts.