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National Grid’s Subterranean Engineers Prep for Last Big Dig on London Power Tunnels

Sept. 11, 2014
National Grid will soon begin digging the last 5.5 km of London’s new 32-km electricity superhighway.

National Grid is set to begin the final phase of tunneling on its flagship London Power Tunnels project. Manned Tunnel Boring Machine (TBM) Evelyn recently completed a challenging 3.4-km stretch of the tunnel underneath the River Thames between Wandsworth and Earls Court.

This involved the twin challenges of digging below the riverbed of the Thames while staying above the path of the proposed Thames Tideway tunnel.  Finding a viable route was further complicated by the presence of depressions in the river bed known as scour hollows which are formed by water currents in the river bed above.
Having successfully cleared the Thames Evelyn – which is manned by a team of expert engineers - is now being prepared for the final stage of tunneling between Earl’s Court and Kensal Green. This is due to start in September and is expected to be completed in early 2015.

National Grid Project Manager John Trounson said: “Digging a tunnel under London is challenging at the best of times due to the presence of so many existing tunnels. However going under the Thames brought further engineering challenges which I’m happy to say our expert team was more than capable of dealing with. With the Thames behind us we can now look forward to completing the last phase of tunneling.”

Installation of the electricity cables that will transport power supplies across the capital began earlier this year and the project is due to be fully complete and operational in 2018.

Trounson added: “London’s one of the world’s leading cities and this project will help it maintain that status by helping to keep the lights on.”

For more information on the project go to

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