The six-year-long London Power Tunnels (LPT) project to help re-wire London, the most significant addition to the capital’s electricity system since the 1960s, is all but complete. The scheme will create ten new 400kV transmission circuits deep underground, replacing and reinforcing the existing network.

The engineering project has involved a Costain-Skanska engineering JV driving three major new tunnels totalling 32km under the capital, creating what client National Grid describes as an ‘electricity superhighway’ for high-voltage cables to provide increased resilience for the city’s power supplies. It is the longest single tunnelling contract ever let to a single contractor in London.

The three tunnels link Hackney in the east with Willesden in the west and Wimbledon to the south, with 14 shafts along the route providing access from street level.

The project saw two tunnel boring machines (TBMs) cutting their way through London’s varying strata at depths of up to 45 metres. Through engagement with local schools, competitions were held to allow pupils to name each machine, with Cleopatra and Evelyn selected as the winning entries.

All tunnelling has now been completed, except one section which cannot be commissioned until next year. When all aspects of the project are complete in 2018, it will help ensure that London’s growing demand for power can be met over the coming years.

Costain agent Andrew Hudspith said: “The project has provided its fair share of challenges. Like any undertaking of this level of complexity, there have been a few issues to solve through its life, but it’s been a very successful contract for Costain and Skanska.”

The first section of the scheme, which was completed last year, will provide power to Crossrail when it comes into service.