Energy minister Michael Shanks visited LPT2 as engineers energised 2.5km of new high voltage 275kV network between Hurst substation and Crayford. The tunnel, which has an average overburden of 35m, was completed by TBM Christine last year.
London Power Tunnels is a £1bn, seven-year project to rewire south London via underground tunnels. In total, 32.5km of 3m-diameter tunnels has been built between Wimbledon in south-west London and Crayford in the south-east, which will carry high voltage electricity cables. Phase 1 of the project was completed between 2011 and 2018, and carried the cable circuits north of the River Thames. The new network will be fully operational in 2027.
Four TBMs built the new network and the final breakthrough was made by TBM Grace in autumn last year.
Shanks visited New Cross substation, a key site at which work is ongoing on the project’s two other double circuits – one between Wimbledon substation and New Cross (12km), the other between New Cross and Hurst (18km).
Also under construction on the 32.5km LPT2 route is a new substation at Bengeworth Road, which, in a UK-first, is being built using SF6-free gas insulated switchgear technology.
The previous cables between Hurst and Crayford, commissioned in 1967, were reaching the end of their operational life. While the old cables were buried in shallower trenches in the streets, the LPT2 network carries power in 3m-wide tunnels beneath the road network, with vertical shafts between 9-15m wide and up to 55m deep sitting above the tunnels at key points, each one covered by a headhouse.
The headhouses and shafts provide ventilation and access for project teams.
National Grid Electricity Transmission president Alice Delahunty said there was still a way to go on the project, but the Hurst-Crayford circuit being switched on was a tremendous achievement for the National Grid teams and supply chain partners.
“It’s hard to overstate what an engineering challenge it has been to build over 30km of tunnels under London to upgrade and futureproof the capital’s electricity supplies, so the project’s progress to date is a real testament to all those involved,” she said.
Since the project began in 2020, National Grid has worked closely with supply chain partners to keep the project on schedule and within budget.
Project partners include Hochtief-Murphy Joint Venture (HMJV) on the tunnels, shafts, headhouses, mechanical and electrical works; Taihan and Balfour Beatty on cable supply and installation respectively; and Linxon on substation works.
HMJV project director Raj Kundan said HMJV and its supply chain was proud to have played a key part, delivering the complexities of the tunnels, shafts, headhouses and M&E infrastructure as well as supporting the wider enterprise.
“The ingenuity and drive of our teams coupled with our ‘One Team, One Spirit’ approach continues to demonstrate our commitment to delivering our client’s desired outcomes whilst leaving a positive legacy – and we look forward to continuing this on the remaining circuits on the project,” he said.
