ELECTRICAL GRID TUNNELS | UTILITIES


Above: Celebrating completion of the TBM drive on Anneberg-Skanstull grid tunnel, in Stockholm, in mid-2025 PHOTO CREDIT: HOCHTIEF-IMPLENIA JV


SWEDEN - ANNEBERG-SKANSTULL Main excavation was recently completed for Stockholm’s key new power tunnel, on the Anneberg-Skanstull section of the electricity grid that is being upgraded and expanded. The Anneberg-Skanstull power cable tunnel project is


being undertaken by the Swedish National Grid (Svenska Kraftnät, SVK) as part of its wider City Link electricity network improvement project. For the Anneberg-Skanstull project, Hochtief-Implenia


joint venture used a Herrenknecht open gripper machine to bore the 5m-diameter through hard rock at depths of 50m-100m. TBM ‘Elektra’ broke through in early May 2025 to finish main tunnelling for the link under the Swedish capital. While the rock was hard, much injected grout was needed for the ground conditions at various points along the project. The project also includes six ventilation shafts,


elevator systems, the construction of technical buildings for electrical equipment at Anneberg and the shafts across the city. The carrier tunnel will connect with substations at


Anneberg and Skanstull parts of the city, respectively. The project is the second of four phases in City Link. While working with the challenges of a major


underground project in the capital, the tunnelling activity also had handle excavations needed close to the Strömmen passage (part of the Baltic Sea) as well as several historic and sensitive buildings, such as the University of Stockholm, museums and galleries.


UK - THAMES CABLE TUNNEL London has seen extensive power cable tunnelling work over recent years, calling for major shaft construction in numerous locations and long TBM drives between those points. One of the next grid tunnel projects near the capital


is the Thames Cable Tunnel, which received planning approval earlier this year. The Thames Cable Tunnel is being built by National


Grid to run below the River Thames, on the estuary side to the east of London, and replace an existing link. The project calls for construction of shafts and then


a 2.3km-long tunnel to run below a wide stretch of the river. National Grid is undertaking the capital investment


to replace the existing Thames Cable Tunnel, in Kent. Originally installed in the 1960s, the current tunnel and cables have reached the end of their operational life. Thames Cable Tunnel is part of the company’s Great


Grid Upgrade to strengthen the UK’s energy network. The new project to replace the old link has received full planning approval. The alignment of the new power tunnel runs from


Grain to Tilbury. In addition to the main carrier tunnel, the project involves construction of new headhouses to access each end of the tunnel, and installation of new cabling. Early construction is underway. Ferrovial is working


in partnership with Bemo (Ferrovial Bemo JV) on the project, which is expected to be completed in 2029.


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