Norway Will Stretch Floating Tunnels Beneath Its Fjords

The country calls them “submerged floating bridges.” Or, y’know, tunnels.

byBen Keeshin|
Norway Will Stretch Floating Tunnels Beneath Its Fjords

Norway's drivers will soon be able to ford the fjords. In a plan expected to be completed in 2035, Norway announced it will be installing floating tunnels, or "submerged floating bridges," one hundred feet below the surface of several of the country's famous fjords.

For many Norwegian drivers, especially in rural areas, the only way to currently cross the deep, craggy-edged gaps is via a series of slow ferries. With the new "bridges"—which, we reiterate, are actually tunnels— the 680-mile drive between the towns of Kristiansand and Trondheim will drop from 21 hours to just 10.5. When finished, the entire route, which traverses seven major fjords, will become a major transportation artery for the country.

How will these "submerged floating bridges" work? Details have been released regarding the first set to be installed, beneath the 4,300-foot deep fjord known as Sogneford. Two 4,000-foot long concrete tubes will be suspended 50-100 feet below the surface of the water, held up by a series of pontoons and secured from below by trusses embedded in the sea floor. Unlike the more typical alternative of a suspension bridge, the tunnels will be protected from most major weather events. On the other hand, the depth of the fjord means a traditional tunnel would have had to have been built more than a mile down, making it financially and structurally unfeasible.

Though the technology is new and unproven, experts say it has enough similarity to existing structures that it shouldn’t be any more expensive or risky. The concrete tubes would be made much like old-fashioned tunnels; the pontoons would be cribbed from floating bridges; the tether technology stolen from that used by off-shore oil rigs. As long as no errant Russian submarines ram the submerged tunnels, long-distance travel for Norwegians should be improving hugely in the coming decades.