The Scandinavian region is well known for its advances in urban planning and efficient transports, but Norway’s latest infrastructure project might be the most ambitious yet. The country’s famous fjords, while beautiful, are difficult and time-consuming to navigate; currently the only way to get across the multiple bodies of water is via ferries. First proposed as far back as the 19th Century by both British naval engineer Sir Edward James Lee and French railway engineer S. Preault, the concept of submerged floating tunnels has been approached with more modern techniques lately. However, none have ever been constructed, making Norway’s US $25 billion plan, announced this week, an exciting new prospect for the engineering concept to come to life.
Also known as Archimedes Bridges, submerged floating tunnels are based on the same engineering concept as floating bridges or off-shore structures, wherein the maximum load the structure can carry is equal to the amount of water it displaces. The construction of these futuristic-looking conduits however, is the same as traditional, fixed underwater tunnels, except for the inclusion of a ballast – a compartment within a boat or other floating structure which is filled with just the right amount of water to make sure the tunnel is roughly the same density as water, to aid floatation. Norway’s planned submerged floating tunnels will also be connected to floating pontoons, visible from the surface of the water, connected with trusses, to keep them stable.
Norway’s multibillion dollar plan will create a network of submerged floating tunnels that each carry a two-way flow of traffic, and are up to 30 meters underwater – deep enough to be out of the way of boats and shallow enough to not require pressure adjustments to protect submerged commuters. Given the extreme depths and widths of the country’s fjords, conventional bridges and tunnels have been deemed unsuitable. Meanwhile, floating and suspension bridges run the risk of instability in high winds or rough waters. Scheduled for completion by 2035, the plan has been allocated the funds necessary by the government, though they have the right to rescind its approval should it be deemed unfeasible or too expensive to implement. If all goes well, however, Norway will have the first such structures in place despite similar proposals having emerged in Italy, China, Indonesia, the US and Canada over the last 20 years.