Since November 2018, two independent project groups have been working on which floating bridge concept is the suitable option for the crossing of Bjørnafjorden south of Bergen.

- Both groups have recommended a c-shaped floating bridge, says Øyvind Kongsvik Nedrebø, Chief Engineer in the Norwegian Public Roads Administration.

The floating bridge will be more than five kilometers long and will cross the 550 meter deep Bjørnafjord between Tysnes in the south and Os in the north.

The NPRA has been working on several concepts for floating bridges over the Bjørnafjorden since 2014. The main alternative was a bow bridge which was fixed at the end on the left side of the fjord, and a straight bridge that also had anchor lines attached to the seabed.

The conclusion was that several alternatives had to be considered. Four variants are the result of the two project groups, AMC and OON (see below). The most important criteria for the work is structural reliability, functionality, cost and aesthetics.

International interest

- The floating bridge project across the Bjørnafjord is groundbreaking, and has attracted great attention abroad. This has led to groundbreaking projects that can resolve challenges that have never been tried before, says project manager Svein Erik Jakobsen at AMC.

The work can be done in Norway

- This is a project that requires interdisciplinary and innovative work, and has attracted attention in the engineering field nationally and internationally, says Kolbjørn Høyland, project manager at OON.

The work we have done, shows that new technology can have great potential for cost savings. In addition, production can be done in Norway. The usual norm is that much of the steel work in such large constructions is produced abroad.

Two professional teams - the same conclusion

– After completing the assignment, both advisory groups recommend the same concept of floating bridge. This is a c-shaped bridge that is held firmly on the left side of the fjord, which is equipped with anchorage points for the seabed. Anchor lines provide significant benefits. The two groups have proposed slightly different solutions for the anchoring system and the location of these. This will be considered more closely in the next phase, Nedrebø says. 

DNV GL (Det Norske Veritas) agrees with the recommendations of AMC and OON.

- With such a unanimous recommendation from a strong professional environment, the Norwegian Public Roads Administration has the basis for being able to present a more accurate cost estimate for a floating bridge over the Bjørnafjorden than earlier, Nedrebø says.

 

The two teams

 OON consists of Dr.techn. Olav Olsen and Norconsult. They also have members from Prodtex, Pure Logic, Institutt for Energiteknikk, Buksér og Berging, Miko Marine, Heyerdahl Arkitekter, Haug og Blom-Bakke, FORCE Technology and Swerim.

 AMC is a working community consisting of consultancy companies Aas-Jakobsen, Cowi, Multiconsult with Johs.Holt, which for the project has also associated companies Aker Solutions, NGI, Moss Maritime, Dissing + Weitling and Entail.