In the 1950s, Erik Ødegård, an engineer with the Norwegian Public Road administration, envisioned a floating underwater tunnel to cross the fjords. Seventy years later, his wish is about to become a reality. The country is planning to build three such infrastructures to link Denmark with Norway via an underwater motorway.

The Sognefjord is the longest fjord in Europe. For tourists, it is one of the most popular walks in Norway because of its waterfalls and rivers. But it is also an impassable border for thousands of motorists. They find themselves forced to make wide detours or wait for ferries. A journey that can last at least 21 hours.

In 2016, the Norwegian government decided to launch a project of tunnels and bridges that will be fully underwater. To connect the waters of the fjords, two concrete tubes will be submerged at a depth of 30 meters, so as not to be subjected to the effect of waves, and not to hinder maritime traffic. These tunnels would either be held by floating pontoons or secured to the bottom of the fjord by steel ropes. This bridge, which would cross nearly 8 fjords, would potentially be the longest floating bridge in the world. A project that would cost around 35 billion euros and would not be completed before 2050.

Underwater galleries

In the Bjørnafjord, an ancient glacial valley, authorities began to think about the idea of a submarine tunnel as early as 2014. They then imagined a structure submerged at only 30m and that would be 5km long. But instead of a tunnel, they will build a hanging bridge. However, other sites are currently being studied to accommodate this type of underwater gallery: two at the Sulafjord sites (4km long) and one at the Digernessundet Strait (600m long). This option is well underway.

Tags: fjord, floating tunnel, Norway, underwater motorway, urban planning