Laing O’Rourke signs contract for three UK substation upgrades

en.Wedoany.com Reported - Laing O’Rourke has signed a new contract with National Grid for works on the Letchmore Heath, Elstree, and St John’s Wood substations as part of the North West London Upgrade. The programme covers the transmission network from Sundon in Bedfordshire to St John’s Wood in London, with the overall works to be delivered in phases through to 2030.

The scope includes the extension and equipment upgrade of the existing 400kV gas-insulated switchgear (GIS) substation at Elstree, the construction of a new 132kV GIS substation at Letchmore Heath on an adjacent site, and reinforcement works at the existing St John’s Wood substation. A new grid transformer will also be installed at Letchmore Heath, with National Grid planning to commence construction at that site in early 2027.

Laing O’Rourke’s scope includes 400kV equipment modifications as well as the installation and relocation of National Grid assets, coordinated with the Letchmore Heath substation works across design, construction, logistics, and commissioning. Laing O’Rourke has been involved in the delivery of the Letchmore Heath project since March 2025.

The North West London Upgrade also includes approximately 60km of new cable, upgrades to over 200km of overhead lines, and the refurbishment of the existing Elstree–St John’s Wood transmission tunnel. The Hochtief-Murphy joint venture is responsible for cable installation and tunnel works, Hyundai Electric is supplying and installing transformers and other major electrical equipment, and Siemens Energy is providing the shunt reactors at Elstree substation. The new Letchmore Heath substation is planned to connect five data centres with a combined electricity demand of approximately 1GW.