London Power Tunnels Project

September 2011: National Grid report that their “flagship London Power Tunnels project has reached a major landmark with the arrival of a massive Tunnel Boring Machine (TBM) named Cleopatra…the device will this week be lowered into a pre-prepared tunnel shaft at National Grid’s site in Eade Road, Haringey. ” The TBM will start digging the 4 metre diameter St John’s Wood  Tunnel – a distance of 8km –  at a rate of approximately 120 metres per week.
The London Power Tunnels Project involves constructing tunnels deep below ground to carry new high voltage electricity transmission cables (400kV) to supply electricity to London connecting National Grid’s existing substations at Wimbledon, St John’s Wood, Willesden and Hackney. Tunnelling Journal reports that “The tunnel will be lined using a Buchan 6 plate trapezoidal gasketed and bolted ring, each 1.3m long, with muck removed via wagons and from the shaft by High Angle Conveyor” in case you wanted to know. Further information on the London Power Tunnels project – with some useful graphics – is provided in this helpful National Grid brochure.