National Grid's Chief Executive Steve Holliday, David Luetchford, National Grid’s Head of Cable Tunnels and Costain’s Andrew Firth, escorted Danny Alexander around the site in north London, which included a trip down a 40 meter shaft to see how the tunnels are taking shape.
"This enormously impressive project is yet more evidence that we are rebuilding Britain. Tunnelling under London in a very confined space to bring the power that London needs to secure the next part of our capital city’s growth," Mr Alexander said.
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National Grid started the seven-year project in February 2011 to ensure that Londoners continue to receive safe and reliable electricity supplies and can access new sources of renewable energy.
Costain is responsible for the £250 million civils work on the project which includes the construction of 32 kilometres of 4.0mID and 3.0mID tunnels, 14 shafts, four connecting tunnels and associated underground chambers. The tunnels will house a new generation of 400kV electricity cabling as part of a 'subterranean electricity superhighway' for London. A tunnel will run from Willesden in the west of the capital via Kensal Green to Hackney in the east. From Kensal Green, another tunnel will be driven south to Wimbledon.
The tunnels are being constructed using a 4.0mID Herrenknecht earth pressure balance (EPB) tunnel boring machine (TBM) and a 3.0mID CAT (Lovat) dual mode TBM from Canada, called Cleopatra and Evelyn respectively. So far the team has completed 20km of tunnels, with tunnelling work due for completion in 2014 and power in all of the new cables expected to be brought online by November 2018.
(CD/MH)
