Norwegen baut den längsten und tiefsten Unterwasserstraßentunnel der Welt

The 27-kilometer (17-mile) long tunnel is called Rogfast — short for “Rogaland fastforbindelse,” after the name of the region it’s in and the Norwegian word for “fixed link.” At its deepest it will be 392 meters (1,286 feet) below sea level.

Construction started in January 2018 but was halted in late 2019 due to predicted cost overruns that led to the cancellation of existing contracts and a restructuring of the project. Work resumed in late 2021 and the tunnel is now slated for completion in 2033, at a cost of approximately 25 billion Norwegian kroner (about $2.4 billion).

But building a tunnel of that length under the sea poses several technological challenges. Like most modern tunnels, to save time, Rogfast is being built from both ends concurrently, with the goal of having the two construction teams meet in the middle within a margin of error of just 5 centimeters (1.97 inches). Achieving this level of precision requires careful measurements using lasers and other sophisticated equipment. A spinning, mirrored laser scanner measures a newly excavated tunnel portion, collecting 2 million data points per second to create a “digital twin” of the tunnel. That can then to be checked against the design plans for any inaccuracies.

Sounds like Switzerland and their train tunnels which take 15+ years to build.

27 kilometers, 392 meter below sea level. 13 000 cars per day (on average). What could possibly go wrong?!

Strange article. Goes on to mention other underwater railway-only tunnels, but no mention of the world’s longest undersea road tunnel, which is located very nearby.