WTC 2025-Tunnelbana Stockholm
Dr. Jan Vesely, Amberg Engineering AG, Switzerland
Miriam Cegrell, WSP Sweden

The new yellow metro line extension will be approximately 8 km long and consists of two single-track tunnels and six underground stations. The paper is written during the preliminary design, the first part discusses challenges for design management and innovations during the design process. The focus is on collaboration between technical disciplines and flexibility. A coordination model enhances this collaboration by allowing all disciplines to work in 3D to identify critical areas and avoid design conflicts. Unlike most tunnel projects in Sweden, the track tunnels will be excavated using a tunnel boring machine and will be designed with a single-shell tunnel lining consisting of precast concrete elements with gaskets acting as the main support system and ensuring watertightness. The use of lining and gaskets reduces the need for pre-grouting and installation of temporary rock support leading to significant time savings. In the second part of the paper, various factors that control the preliminary design are discussed.