German tunnel portal: structural works completed

Concreting work on the tunnel portal, the entrance to the Fehmarnbelt Tunnel, began at the German construction site in autumn 2023. A lot has happened since then: a total of 450 metres of cut-and-cover tunnel and a 150-metre light transition zone have been constructed in the construction pit. The approximately 600-metre-long section of tunnel on land was built in segments. For each segment, the base slab was concreted first, followed by the side walls and finally the tunnel roof, using conventional construction methods. The final section of the tunnel roof was concreted in October 2026, completing the structural works on the tunnel portal.

“It is impressive to see what has been achieved here at the German construction site in just a few years. Many people from different trades have worked extremely hard to make this possible. I am very proud of what we have achieved together,” says Matthias Laubenstein, Contract Director at Sund & Bælt.

An important step towards completing the structure was the removal of the temporary retaining dyke, which had long formed the boundary of the construction pit for the tunnel portal. After the first 100 metres of cut-and-cover tunnel were completed in summer 2024, a new dyke was built above this section. Bulkheads were installed in the tunnel tubes at the seaward end to make them watertight. The area between the new dyke and the temporary retaining dyke could then be flooded and the retaining dyke removed. In autumn 2024, the time had come: the seaward section of the cut-and-cover tunnel was under water. This is where the first immersed tunnel element on the German side will later be connected.

Since then, the cut-and-cover tunnel has continued to grow inland from the coast. In addition to the tunnel portal, a portal building has been constructed to house tunnel technical equipment, as well as ramps that will carry the road and railway into the tunnel.

The concrete used for this work did not have far to travel: it was produced at the on-site concrete batching plant. Most of the materials required are delivered by cargo vessels via the Puttgarden work harbour, which has been in operation since July 2023. This avoids the need to transport these materials across the island of Fehmarn by lorry.

Some finishing work is still being carried out on the German tunnel portal structure, including work on the openings in the light transition zone. At the same time, work inside the tunnel tubes is beginning. This includes installing fire protection panels on the walls.
Before the first tunnel element can be immersed on the German side and connected to the tunnel portal, further elements will first be immersed on the Danish side and the tunnel trench off the German coast will be prepared.