Can Norway Build the First Floating Tunnel In the World?

concept drawing: government of Norway

Earlier this year, the government of Norway decided to undertake the largest infrastructure project in the world, a “highway” to connect the entire country from top to bottom — crossing under, over and through its more than 1,000 fjords.  The $40 billion dollar project will make it possible to drive the 1,100-kilometer journey from the southern city of Kristiansand to northern Trondheim along the west coast that currently takes 21 hours and requires seven ferry crossings, completely ferry-free and in half the time. The most futuristic part of the undertaking is the development of submerged floating tunnels that sit around 30 meters (100 feet) under the surface of the water — and Norway is racing other countries such as China and Italy to be the first to complete this feat.

Why This Matters:  This would be another amazing engineering accomplishment and could be less environmentally disruptive than more conventional projects or current modes of transport.  The government sees this as a key to improve transport “for commercial purposes (and) also for the welfare of the local population,” according to CNN.  More than 50% of export goods in Norway originate along the west coast but the current route “has a very low standard for a European road.”  This is what governments should do — massive infrastructure projects that will boost the economy and the way of life for its people — that are too big for private corporations or regional governments to undertake.  

How to Build a Floating Tunnel

Well that is THE question they are trying to solve.  Why do you need them?  When a fjord is deeper than 1 kilometer (0.6 miles) or wider than 5 kilometers (3 miles), however, existing solutions like bridges and tunnels don’t work because the seabed would be too deep to be drilled through for a rock tunnel or for a suspension bridge’s foundations to be laid.  And floating bridges won’t work either — it’s too windy and there’s too much current to make them safe. Instead, they are designing tunnels that are fixed in position with cables — either anchored to the seabed or tethered to pontoons which are spaced far enough apart to allow boats to pass through.  The tunnels themselves would still be made of concrete but would not move because waves and currents at 100 feet below sea level where these would float are less powerful than those at the surface.

What Could Go Wrong?

The government of Norway and its engineers are leaving nothing to chance.

“We have done simulations for big explosions in the tunnel, we’ve checked for impacts of submarines, we covered scenarios where a trawler might hook onto the tunnel, and we even considered if a ship might be sinking at the surface and hit the tunnel on the way down,” Rønnquist said. “I would say things are under control. It’s a very robust structure.”

NBC News reported that just like other tunnels, there would be escape routes that motorists could take to return to the surface in case of an emergency. According to the government, “preliminary research regarding the proposed tunnel’s safety has been reassuring.”

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