World's longest immersed tunnel: Third element sunk for Fehmarnbelt link

A significant milestone has been reached in the construction of the Fehmarnbelt Fixed Link, the world's longest immersed tunnel, as the third of 89 massive concrete elements was successfully sunk into the Baltic Sea.

The 18-kilometer tunnel, a major European infrastructure project, will connect Germany's Fehmarn island with Denmark's Lolland island. Once completed, it will accommodate a four-lane highway and train services, significantly reducing travel times across the Fehmarn Belt. Cars are expected to make the journey in approximately ten minutes, while trains will take about seven.

Each of the 73,500-ton tunnel elements, comparable in size to a cargo ship, is manufactured in Rødbyhavn, Denmark. The third element, named Heiligenhafen, was transported by five tugboats and precisely positioned on the seabed before being connected to the existing tunnel structure. The sinking process is described as a complex precision task requiring the coordination of many components.

Despite this progress, the ambitious project is facing considerable delays. The original completion date of 2029 is no longer feasible, with the tunnel operator now anticipating completion after 2030. Germany also expects delays in the construction of the necessary land-based connections, pushing the overall project timeline further back.

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Every sinking process is a demanding precision task where many components must work together.