Building the tunnel

A tunnel portal is built in both Denmark near Rødbyhavn and in Germany near Puttgarden. The portals connect the tunnel's railway and motorway with the upgraded and newly built roads and railways in the hinterland. 

Work on excavating the construction pit for the tunnel portal on the Danish side began in 2020, with work on the German side starting the following year.

The tunnel sections for the tunnel portals are constructed using the cut and cover-method in the excavation pits. First, the bottom slabs are cast, then the side walls and finally the top slabs of these tunnel sections on land. The front section of the tunnel section built on land is now under water on both sides of the Fehmarnbelt. The tunnel elements can then be immersed and connected there – first on the Danish side, then later on the German side.

The large factory near Rødbyhavn, where the 89 tunnel elements are being produced, consists of a total of six production lines. In July 2023, work began there on casting the tunnel segments (each tunnel element consists of nine segments). The first elements have now been cast. A total of 79 standard and 10 special elements are being produced.

The special elements have a basement that houses the tunnel's technical equipment. This facilitates subsequent maintenance of the tunnel. The tunnel elements are produced in industrial series production, which makes construction particularly efficient.

The elements will be cast step-by-step in segments of approximately 24 metres in the factory. Nine segments comprise one standard element and the whole process takes about nine weeks.

A high degree of uniformity and quality in the casting can be ensured because it takes place inside climate-controlled halls. This is important as the Fehmarnbelt tunnel is designed to operate for at least 120 years.

When an element is ready for shipment, it gets waterproof bulkheads fitted at both ends and is towed into place using tugs.

The elements are then immersed to the seabed with high precision and are carefully connected to each other. There is a sealed space between the bulkheads so that huge external pressure pushes them together when the water is pumped out. This ensures a completely waterproof connection.

Once the elements are assembled, work on the tunnel’s technical and mechanical installations can begin. These include railway tracks, ventilation, cameras, communication systems, signage, painting and much more.