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Floating bridge could slash cost of linking islands

A floating bridge design being developed for the Norwegian government could prove a cheap way of linking islands all over the world, the firm behind it has claimed.

Norwegian civil and structural engineering company Degree of Freedom is working with local engineering advisory firm Multiconsult and the country’s government to produce a cost-effective crossing over water that does not need to be navigable.

“The idea is to be able to use it in a lot of different places and to make it scalable,” said Degree of Freedom partner and director Felice Allievi. “If we come out with something that works with the challenge we have now in Norway – really, you could use it everywhere.”

Floating bridges could be built as a series of repeatable units where the per-metre cost would remain the same without the traditional step change in cost associated with increasing distance.

“Compared to the cost [of a suspension bridge] - it’s very low,” said Allievi. “If you compare 4km to 6km on the same sea depth, the price per square metre doesn’t change,” said Allievi.

Speaking at the ICE bridges conference, Multiconsult bridge director Birger Opgard described the crossing as being made up of a series of stationary sections joined by a chain-link that is free to move.

“It’s like a chain on a bicycle,” said Birger.

The stationary elements, he said would be supported by pontoons, and anchored in place with cables to the sea bed.

On plan the bridge is S-shaped with the cables to the sea bed placed on the outside of each of the bends like eyelashes.

“When the waves come from one side there is tension in half of the anchors and the others will be slack, but there is tension in the bridge,” said Birger.

The development team hopes the research will come to fruition within the next two years.

Readers' comments (2)

  • Excellent Innovation, when this design development is complete It will offer signaificant cost savings I'm sure. Among the challenges will be the interface at the stationary points as the chain link moves.

    good luck

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  • Having recently looked into catenary and chain tension formulae for a project, the concept is excellent and I can see that it will offer big savings. The presentation from multiconsult was one of the most interesting parts of the recent ICE Bridges Conference. I will be interested to see how the joints are designed and how well they last given the large range of movement required, and because the bridge will be situated near to the sea in a very aggressive corrosion environment.

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