When a 140-tonne tunnel boring machine emerged into daylight at Eltham substation over the weekend it marked completion of 32.5km of tunnelling at depths of up to 60 metres under seven south London boroughs.
The final drive was an 11km eastwards bore from National Grid’s New Cross substation in Southwark.
Installation of 200km of high voltage cable is already under way between substations at Wimbledon and Crayford.
Hochtief Murphy Joint Venture (HMJV) began construction of the tunnels in March 2020. The transmission infrastructure that they are built to carry is due to be fully operational by 2026, with the aim of reinforcing and future-proofing London’s electricity network.
National Grid Electricity Transmission president Alice Delahunty said: “Our London Power Tunnels project has achieved a lot since it kicked off in 2020, but the final tunnelling breakthrough at Eltham is a particularly remarkable moment.
“This complex engineering endeavour is now really taking shape, with completion of tunnelling now physically linking our sites across south London for the first time and meaning we can move on to the next chapter to progress our vital cabling work.
“The outstanding effort by our project teams and suppliers is strengthening London’s electricity network and making sure it safely, reliably and efficiently powers homes and businesses in the capital for years to come.”
HMJV project director Santiago Daniele said: “It’s been an incredible journey so far, from taking over our tunnel drive sites a week after the covid lockdown, to sinking eight shafts and undertaking five tunnel drives with four TBMs over the past three and half years.
“With our final TBM drive breaking through at Eltham ahead of the original baseline programme, it’s testament to the collaboration, ingenuity and fantastic joint culture of all involved – despite all of the challenges faced. This remarkable achievement has laid a solid foundation for the Enterprise in achieving National Grid’s vision of rewiring London and connecting with the capital.
“We’re incredibly proud to be delivering for National Grid a scheme of such significance – and being their delivery partner of choice for complex major infrastructure involved in LPT Phase 2.”