Construction of the Fehmarnbelt tunnel began in 2020 on the Danish side, and in 2021 on the German side. You can find the overall schedule and the various phases of construction here.
Tunnel factory
The tunnel construction site near Rødbyhavn covers an area equivalent to around 300 football pitches and is the largest in Europe. More than 2,000 people from over 40 countries work there.
The tunnel factory consists of three production halls – A, B and the smaller C, with a total of five production lines for the standard elements.
The Fehmarnbelt Tunnel is built from 79 tunnel elements, each 217 metres long. Each standard element comprises nine segments that are cast in an assembly line production. Once a segment is cast, it is pushed forwards for curing and the formwork is prepared for the next segment until all nine segments are ready. On a sixth line, 10 smaller special elements with a basement housing the tunnel's electrical installations are built.
Two large concrete batching plants are located right next to the production halls and can jointly produce more than 600 cubic metres of concrete per hour.
But there is still some final work to be done before the individual elements can be moved to their final destination and immersed into place in the tunnel trench. Technical installations, watertight bulkheads and ballast tanks are then fitted. The ballast tanks compensate for the difference in weight between the road and railway sections and allow the elements to be immersed with accuracy. Other preparatory work is also carried out on the element.
Once the work has been completed, the basins in front of the factory are flooded and the finished elements are transported to the work harbour. Additional ballast concrete is added there so that the elements no longer float independently. Now it will be kept afloat by the immersion pontoons.
Panel Factory for steel processing
The Panel Factory is located southwest of the production halls. This is where the many thousands of tonnes of rebar that arrive at the work harbour are assembled into large grid structures that form the skeleton of the tunnel elements. They are then transported to the tunnel factory where they are assembled prior to casting.
Most of the production of the lattice structures is performed with help of several welding robots. The finer work is carried out manually by welders.
Panel Factory covers around 25,000 m2 of the construction site and employs around 100 employees.
Work harbours
Blue Water Harbor Management is responsible for the operation of the two work harbours on the German and Danish side of the Fehmarnbelt. Almost all materials required for the construction sites are delivered directly by ship via the harbours. This simplifies logistics and avoids the transport of construction materials over land by many thousands of HGVs.
The Danish work harbour has been in operation since summer 2022. A cargo vessel arrives in Rødbyhavn approximately every third day andaround 65,000 tonnes of stone, cement, sand, gravel and steel are handled there every week.
The German work harbour, built specifically for the project, has been in operation since July 2023 and receives approximately two vessels per week. Cement silos and additional storage areas for the delivered materials are located next to the pier.
Accommodation facility at the Danish tunnel construction site
The accommodation facility, with more than 1,300 residential units, was completed in summer 2023. In addition to a self-service supermarket, the site also offers sports and recreational facilities.
Tunnel portals
Tunnel portals are being built on both sides of the Fehmarnbelt to connect the immersed tunnel with the motorway and railway lines on land. The tunnel sections on land are largely complete, and the ends facing the Fehmarnbelt are already underwater, where they serve as connection points for the tunnel elements.
The Danish tunnel portal has been completed and covered with soil. It also includes a railway ramp more than 800 metres long and an approximately 100-metre-long light transition zone. A new dyke has formed the coastline since 2024. In May 2026, the first immersed tunnel element was connected to the portal.
The German tunnel portal in Puttgarden is almost 600 metres long and is nearing completion, with almost all of the concrete work finished.
Work in the Fehmarnbelt
Work at sea began in June 2020. Some 2 million tonnes of Norwegian granite were used for the creation of the new coastline while dredging and reclamation was performed by up to 60 vessels.
The dredging of the tunnel trench, which was completed in 2024, resulted in almost 15 million m3 soil, stone and sand, which are reused for around 300 hectares of new nature and recreational areas at Rødbyhavn.
Customised dredgers such as the Hopper Dredger, Vox Amalia, the Wire Grab Dredger Manta and Magnor, the world’s largest Backhoe Dredger, were used for the operation.
The contractor is now using a number of purpose-built vessels for the immersion of the tunnel elements in the tunnel trench.
The special vessels are:
• Multi-Purpose Pontoon, Maya, which lays out an even gravel bed upon which the tunnel elements will be placed.
• Immersion Pontoons Ivy 1 & Ivy 2, which have been specifically designed to support the tunnel elements during their journey from the work harbour to the tunnel trench and to immerse the elements.
• Spreader Pontoon, NP460, which puts stones and gravel along the sides of the tun-nel element to lock it into position.
• Protection Layer Pontoon, Wismar, which lays out a protective layer of stone on top of the element.
In May 2026, the first element was immersed off the Danish coast and connected to the Danish tunnel portal. Following the first tunnel element, the second element was successfully placed in the tunnel trench off Lolland at the end of June, followed by the third element at the beginning of August. By the end of September 2026, the fourth tunnel element had already been immersed and connected to the previous elements. This means that the first almost 900 metres of the tunnel are now in place on the seabed.
In the next step, the first special element will be immersed. It has an additional basement level for technical installations and is approximately as tall as a four-storey building. In September, the special-purpose vessel “Ivy” successfully passed the required load test and is now ready for the task.
The construction site at Puttgarden
The German construction site is significantly smaller than the site in Denmark, but still forms a crucial part of the project area. The work is carried out at planned staggered intervals in relation to the work being carried out at the Danish construction site.
On 29 November 2021, the official groundbreaking ceremony took place on the German side. The construction site was fully developed and set up during 2021. The approximately 90-hectare construction site on land has since visibly taken shape.
In future, the E47 motorway and the new railway line will lead into the tunnel portal. A total of three bridges must be built at the German tunnel construction site for the new alignment. Two of the three bridges have been completed.
Work on the third bridge began in 2025.
Some of the marine material excavated from the tunnel trench is being temporarily stored at the German construction site and is now gradually being reused as construction material, including for the embankments along which the new E47 motorway will run
Marine construction work on the coast of Fehmarn began in October 2021. A large excavation pit has been created behind the former coastline, where the tunnel portal on the German side is being built. In autumn 2023, work began on constructing the cut-and-cover tunnel sections in the excavation pit.
The German portal consists of two parts: a 450-metre-long section, which is being built as a cut & cover tunnel and an approximately 150-metre-long light transition zone, which provides for a smooth transition to the motorway and railway on land. Work on the German tunnel entrance is already well advanced.
