Longtime Slashdot reader Qbertino writes: The Fehrmarnbelt tunnel is a European construction megaproject building a tunnel between Denmark and Germany, crossing the Fehmarnbelt in the Baltic sea. The first segment of the tunnel has now successfully been placed in its designated spot . This is a yet-unseen, next-level engineering feat achieved by the Danish Sund & Baelt construction company. It took 14 hours and used a massive pontoon ship built specifically for this project. The tunnel segments are 217 meters long, weigh more than 73,000 metric tons, and have to be placed within a tolerance of 3 mm. The tunnel will eventually consist of 89 of these segments, be 18 km long, and connect the Danish city of Rodby with the German island Fehmarn through five individual tunnel tubes: two for cars, two for trains, and one rescue and maintenance tunnel.…