A Floating Tunnel for Norway

Is it a tunnel? Is it a bridge? No, it is a combination of both! The Norwegian Public Roads Administration (NPRA) proposed an underwater tunnel hanging from floating pontoons from the southern city of Kristiansand to Trondheim in the north. Now travellers are facing seven ferry crossings and a drive of 21 hours to overpass the western coastline. According to Wired, the infrastructure could cost over 22 billion euros.

The west side of Norway consists of 1.190 fjords, which creates serious obstacles for long distance travelling. The deepest fjord in Norway, the Sogn, is over 3.000 feet deep, which makes it impractical to build a traditional tunnel or a bridge - think about the ships passing the Norwegian Sea. Therefore, the team of NPRA presented a suspended tunnel that cuts across seven fjords.

According to their unsettled plans, these 4.000-foot long curved concrete tubes would be hanging 100 feet below the surface. Pontoons on the surface are holding the tubes, at the same time leaving room for ships with no trouble passing above. According to Arianna Minoretti, senior engineer at Statens Vegvesen, driving through the tube simulates passing through any other tunnel. She states: “For the user, the structure will be indistinguishable from a tube-shaped tunnel […] but in terms of its behavior, it has much more in common with a bridge”.

The concept derives from the Archimedes Principle, named after the Greek Mathematician who first thought about it while taking a bath. While entering the tub, the water rose, which made him realize this could be used to regulate the volume of his body immersed in water.

The upgraded highway is part of a series of solutions for the coastal Route E39 and is expected to reduce travel time to just 11 hours. What is more remarkable is that the tube maintains the beautiful outlook of the Norwegian countryside, as it is located under water.

Source: World Economic Forum