The world’s longest floating bridge over Bjørnafjord

As part of the project to establish a ferry-free E39, the Norwegian Public Roads Administration is working on solutions for ferry-free connections across the fjords along the 1,100 kilometre coastal route between Kristiansand and Trondheim. 

The combination of waters up to 550 metres deep and bridge lengths of up to 5 km makes it impossible to use conventional bridges. Floating bridges and submerged tubular bridges are the only feasible ways of making a road link across such a wide and deep fjord. COWI headed one of the three working groups looking at possible bridge solutions to cross the 5 km wide Bjørnafjord.

The working group looked into project designs for two different floating bridge concepts. One alternative is a side-anchored straight bridge. The stays are taken down to the sea bottom at depths of up to 550m. The second alternative is an end-anchored curved bridge. Various options for a high bridge over the shipping lane were also evaluated. The recommended solution for both side-anchored and end-anchored bridges is a cable-stayed bridge with tower. The tower will be placed on Svarvahelleholmen to the south. The span of the cable-stayed bridge will be almost 500m, making it one of the longest in the world for this type of bridge.

The working group performed a number of analyses requiring top-level expertise in marine operations, hydrodynamics, wind dynamics, structural engineering, risk analyses and load response to impact from ships.