National Grid’s £1bn London Power Tunnels take shape

National Grid has hit a key milestone on its £1 billion London Power Tunnels project.

The project reached a landmark moment this weekend (30 September) as the 140-tonne tunnel boring machine broke through at Eltham, which marks the end of tunnelling on the project.

In total, the project consists of 32.5km of tunnels at depths of up to 60 metres under seven South London boroughs.

Due for completion in 2026, the project is rewiring the capital’s electricity network to boost resilience and future-proof supplies as demand grows.

The last of the project’s tunnel boring machines, named Grace, broke through on Saturday, having tunnelled over 11km eastwards from National Grid’s New Cross substation in Southwark.

All 32.5km of the project’s underground route are now complete, with installation of 200km worth of high voltage cable – enough to stretch from London to Cardiff – already underway between substations at Wimbledon and Crayford.

Construction of the tunnels began in March 2020 with the tunnelling works undertaken by National Grid’s delivery partner Hochtief-Murphy Joint Venture (HMJV).

Alice Delahunty, president of National Grid Electricity Transmission, 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.”

Santiago Daniele, HMJV project director, added: “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.”