The civil engineering team working on National Grid’s London Power Tunnels, which will create a new 32 km electricity superhighway under London, have broken through at Wimbledon.
The tunnels will house 10 new 400 kV circuits totalling 192 km, as well as 32 km of 132 kV circuits.
Since work started in 2011, the team has built 14 new shafts and bored 18 km of tunnels, which plunge between 20 m and 50 m below ground.
Two tunnel boring machines (TBMs) are being used on the project; ‘Evelyn’ which is 3 m internal diameter (ID) and ‘Cleopatra’ which is 4 m (ID).
An average distance of 55 m a day was tunnelled by Evelyn on the stretch down to Wimbledon, breaking through on 15 August, with 96 m achieved as a maximum in one day.
Approximately 31,000 cu m of excavated material was produced, with 100 per cent of it being recycled.
Commenting on the breakthrough, achieved eight days ahead of schedule, construction director Lennart Stenman said: “It’s a major milestone to achieve and the team should be rightly proud arriving ahead of programme.”
At any one time up to 250 people are working on the project with Costain, which is scheduled for completion in 2018.