The Söderström tunnel as part of the Citybanan project is an approx. 300 meter long submerged tunnel that crosses under the Söderström and a branch of Lake Mälaren and is located between two rock tunnels.
The new “Citybanan” railway line was built in the heart of Stockholm. It will cross under the city center as a 6 km long tunnel and will help to ease the current traffic situation.
The rectangular tunnel cross-section with the external dimensions of 20 x 9 meters has a double-track main tunnel and an adjacent service tunnel.
The three approximately 100 meter long tunnel elements, consisting of concrete hollow boxes in steel formwork, were floated in, lowered and connected. BBV L19 tendons running over two sections were then installed under water in the floor, ceiling and walls of the tunnel, post-tensioned and injected with mortar.