The blue building site

To a large extent, the Fehmarnbelt tunnel is a maritime project. The 'blue' construction site between Denmark and Germany will be the workplace for several hundred seamen and up to 60-70 vessels.  

In June 2020, work began on the construction of the new breakwaters off Rødbyhavn, where the dredged material from the Fehmarnbelt will be deposited. These breakwaters will move the coastline 500 metres further out into the Fehmarnbelt and the result will be around 300 hectares of new nature and recreational areas.

More than 2 million tonnes of granite have been imported for the construction of the breakwaters. The boulders come from four quarries on Norway’s south coast. The work is being carried out by the FBC consortium.

Prior to the immersion of the elements for the Fehmarnbelt tunnel, a trench must be dredged between Denmark and Germany. The trench will be approximately 18 km long and 12 metres deep. The width will vary depending on the sea depth and the composition of the seabed. A total of 19 million cubic metres of sand, stone and soil will be dredged.  

The work will be carried out by a fleet of special dredging vessels and barges, which will transport the dredged material inland, where it will be deposited in the reclaimed areas. The work will be monitored round-the-clock by special environmental vessels, which will check that the amount of sediment in the water does not exceed the threshold stipulated in the plan approval.

When the tunnel elements have been completed at the factory, they are fitted with pontoons and towed out to sea for positioning on the seabed. Using a coordinate system customised for the Fehmarnbelt, the 217 m long standard elements can be positioned with millimetre precision, specifically 15 millimetres.   

When the element is ready for immersion, the ballast tanks are gradually filled with water so that the element is heavy enough to descend into the tunnel trench. Tugboat operators can monitor the immersion on cameras mounted on underwater robots. The entire operation takes several hours.