Bjørnafjorden floating bridge

Assignment

The Norwegian Public Roads Administration is planning to build a bridge crossing the Bjørnafjord, to replace todays ferry connection between two of Norway’s largest cities, Stavanger and Bergen. Such a bridge would have to be over 5 km long, and with extreme water depths, foundations to the seabed is not a viable solution.

Solution

A floating bridge crossing the Bjørnafjord would need a cable stayed bridge in one end, to secure a free ship clearance entering the fjord. The cable stayed bridge is comparable with the world largest bridges of its kind, with a tower height of 215 m and a free cantilever of approximately 400 m during construction. The floating bridge will have a total length of 5440 m, approximately 4 times the length of the current longest end-anchored floating bridge. The investigations of crossing the Bjørnafjord has been performed through three phases. Norconsult has been involved i all phases, and in phase 2 and 3 they worked with the floating bridge concept. In phase two, an end-anchored floating bridge was investigated, and Norconsult proposed optimization measures resulting in total cost reductions of over 30 %. In phase 3, four different subcategories of end-anchored and side anchored floating Dynamic effects from wind and wave loading, ship impact and complicated marine operations and installation phases was among the main challenges in this project. Optimization of the structure and the construction was very important, both for cost savings and the environmental aspect. Robotized production of the closed steel box girder was investigated, presenting new challenges to develop steel details suitable for such production methods. bridges was considered, with the aim of recommending one final concept solution.