First they built a bee highway, then they gave Finland a mountain, and then they created a game of microscopic Pac Man. Now the Norwegians are setting aside a cool $25 billion to build the world’s first floating submerged tunnel system.
The project aims to speed up travel across the country and will connect the southern city of Kristiansand to the northern city of Trondheim. As is, the journey by land takes 21 hours to complete and seven fjords cut into the route, requiring that travelers take ferries to cross the waterways.
“This idea of Norway’s is sort of an intermediate technology of things that have been done before,” said Duke University civil engineer (with a specialization in bridges) Henry Petroski.
The waterways are too wide for typical bridges, so the submerged tunnel system will live roughly 100ft underwater and are said to be the most practical solution to the aforementioned problem. The tunnels will be constructed with 1,200m curved concrete tubes held up by pontoons on the surfaces. Wide gaps between pontoons will allow ferries to pass through. Arianna Minoretti, a senior Norwegian engineer with NPRA, says you wouldn’t even know you’re underwater, as the experience would be similar to that of standard tunnels.
The tunnels will serve more uses than just making the cross country trip quicker, though. Minoretti says that “this connection means that people there do not have to wait for a helicopter to go to the hospital.”
That said, there are plenty of questions that all have to be answered before any real contraction begins. One of the most important has to deal with the aforementioned fjords. The seabeds have to be mapped out and the teams have to determine whether or not the bedrock can support the tethers needed to keep the tunnel “from becoming a car-filled Slinky.” What’s more, engineers have to calculate the wind and waves that the tunnel can handle in addition to how currents from the fjords could affect its movement.
Throw in some structural integrity questions, maintenance and all that and you’ve got yourself a massive project. Norway hopes to have the whole shebang completed by 2035.
In the meanwhile…