Submerged Floating Bridge
  • Description of the forecast
  • Description of the implementation
‘Submerged Floating Bridge’ Is a Reasonable Way to Cross a Fjord, if you want to drive the 680 miles from Norway’s bustling southern port of Kristiansand to Trondheim in the north, be ready to spend 21 hours in the car.

That’s an average of 30 miles per hour, and you have the country’s signature geological features to thank. The route, along highway E39, crosses seven gorgeous but inconvenient fjords, and that means seven ferry trips.

Now, a $25 billion infrastructure project promises to cut the trip to just 10.5 hours, by installing permanent crossings across those fjords by 2035. Because many of these waterways are wide and the largest is nearly a mile deep, a typical bridge won’t do. So Norway is considering fording its fjords with something the world has never seen before: a submerged floating bridge.

That’s the fancy term for a traffic tube that’s under about 100 feet of water—and above hundreds more.

It’s not actually that crazy, says Arianna Minoretti, a senior engineer with the country’s public roads administration. According to their tentative plans, the 4,300-feet deep, 3,300-feet wide Sognefjord may be the perfect candidate for this first-of-its kind crossing. The structure would be made up of two curved, 4,000-foot long concrete tubes—one for each direction—hanging 65 to 100 feet below the surface.

Pontoons on the surface would hold up the tubes, and connecting trusses would keep them stable. The structure might also be bolted to the bedrock below, for extra stability. Driving through one of these would feel like driving through any other tunnel, says Minoretti. (For a preview, claw through New York’s Holland Tunnel at rush hour, and imagine there’s water below you as well as above.)

The design offers plenty of advantages over saner-sounding, conventional alternatives. Rough weather won’t mess with the underwater structure, Minoretti says, so Norway’s more rural residents never get stranded. “Having this connection means that people there do not have to wait for a helicopter to go to the hospital.”

Norway’s also considering building a suspension or floating bridge over the water. Either could mess with the Navy ships that sometimes train in these waters, and mar the majestic, fragile, and highly bankable beauty of the fjords. (Digging a standard tunnel as far as a mile below the surface is impractical.) A floating tunnel obviates those problems—and shouldn’t be any more expensive than the saner-sounding, conventional alternatives, the engineers say.

About this event in a different language: русский


Source: Wired

Yet waiting for realization


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Norwegian Public Roads Administration

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The Norwegian Public Roads Administration (Norwegian: Statens vegvesen) is a Norwegian government agency responsible for the state and county public roads in the country. This includes planning, construction and operation of the state and county road networks, driver training and licensing, vehicle inspection and subsidies to car ferries.

The agency is led by the Directorate of Public Roads (Vegdirektoratet) that is subordinate to the Ministry of Transport and Communications. The Norwegian Public Roads Administration is divided into five regions and thirty districts, which are subordinate to the directorate. The directorate is based in Oslo.