Submerged floating tunnels for crossing of wide and deep fjords

Increasing traffic volume and more focus on industrial effects, time saving effects and environmental effects have in Norway increased the focus on establishing permanent connection for several wide sea links. The Norwegian topography, with wide and deep fjords, makes establishing such permanent connections a challenge and has made bridge design to be an important topic in the development of Norway. In order to cross deeper and wider fjords new designs and new concepts have been developed and adapted continuously.The feasibility of the submerged floating tunnel as a concept for fjord crossing was proven in the Høgsfjord project. Four different concepts were here prepared for construction for a crossing of approx 1400 m length. All concepts were evaluated as feasible for construction of the national authorities.In the wake of the Høgsfjord project, feasibility studies have been undertaken in Norway for several other locations. This paper addresses some of the challenges of conceptual development of the submerged floating tunnel from the Høgsfjord concepts towards concepts for deeper and wider fjords. Challenges are illustrated on concepts for crossing the Norwegian fjords, Norfjord and Storfjord on the west coast of Norway, crossings sites which are 1800 m and 2500 m wide and 150 m and 400 m deep, respectively. The final challenge will be a crossing of Sognefjord where the identified crossing site is 3700 m wide and 1250 m deep.