Statnett has built a tunnel for new cable interconnectors between Smestad and Sogn in Oslo.
The new cables will replace the current two cable interconnectors between Smestad and Sogn, owned by Elvia. The cables are from 1955 and 1977 and are nearing the end of their technical lifespan. Smestad substation was built in 1952. Capacity at both the substation and the cables must increase to provide a better supply of electricity to residents in Oslo.
Prior to applying for a licence to build Statnett thoroughly explored two potential solutions for the cable interconnectors between Smestad and Sogn: cable in tunnel and cable in trench. We mapped buildings, infrastructure, roads and the environment, assessed emergency preparedness, risk for the surrounding areas and made economic calculations. Throughout the process, we have had meetings with local authorities and public agencies to receive their input.
A tunnel has many advantages compared with a trench. Cables in a separate tunnel are less exposed to damage, easier to inspect and easier to maintain and repair. They provide greater flexibility, have less impact on the environment, and are generally more profitable and have a shorter installation period. A tunnel is a secure, robust and forward-looking solution for the Oslo main grid.
Based on a comprehensive assessment, a tunnel was considered the best solution for security of supply and the surroundings. We therefore applied for a licence from the authorities to build a separate tunnel for the new cables between Smestad and Sogn.
Smestad and Sogn substation
Statnett has renewed Smestad and Sogn substations and the cable connection between Sogn and Smestad.