The National Grid’s London Power Tunnels reached a significant milestone with the breakthrough of the 140-t Herrenknecht tunnel boring machine (TBM) in June nearly a year after its launch.

It is one of four TBM’s at the project that will put London’s power cables up to 50 meters under the streets of the city. The three other TBM’s are still at work.

The Construction Index reported 32.5 km (20 miles) of 3 m (9 ft) diameter tunnels are being constructed between Wimbledon and Crayford in what is phase two of the project.

Phase 1, a seven-year £1billion project that was completed in 2018. National Grid says that LPT phase two is currently under-budget and on time to complete in 2027.

National Grid project director Gareth Burden said: “After close to a year of tunneling, it is exciting to see the first connection between sites. The team has worked so hard to make this happen, in the face of tough ground conditions. Thanks to Hochtief Murphy Joint Venture (HMJV), Herrenknecht, our engineers, fitters, miners and everyone else involved. A special thanks also goes to the Joseph Gallagher Limited gangs who put in some hard yards down in the tunnel. It’s great to take a moment to celebrate with them and see the flags and kits proudly on display.”