The immersion of the first tunnel elements on the Fehmarn connection is planned for no earlier than March 2026. This is evident from a German construction and schedule plan, which FemernBusiness has obtained access to. The schedule is part of the monthly reporting that Femern A/S submits to the German authorities, and it shows the client's planning as of 1 December 2025.
The schedule concerns the immersion of the 89 tunnel elements that will constitute the actual connection between Denmark and Germany. The Fehmarn connection is an 18-kilometre-long immersed tunnel, being constructed by the international contractor consortium Femern Link Contractors for the state client Femern A/S under Sund & Bælt. With a total construction budget of around 67 billion DKK, the project is the largest construction project in Danish history.
The tunnel elements are cast on land at the work harbour on Lolland and then sailed out to the Fehmarn Belt. Here, they are lowered into an excavated trench on the seabed, where the elements are connected. The immersion is the most critical and time-sensitive part of the construction, because the process requires several conditions to be met simultaneously, including that the tunnel trench is ready, that special vessels and equipment can operate as planned, and that the necessary authority approvals are in place.
More than three months of testing
The German schedule, a so-called Bauzeitenplan, places the start of the immersion in the third month on the timeline for 2026. Since the plan indicates the status as of 1 December 2025, it means that in the current planning there are more than three months from the status date to the planned start of the immersion.
A central element in the immersion work is the special vessel Ivy, which has been developed specifically for the Femern project. The vessel has not yet been finally approved. Femern A/S has previously closely linked the start of the immersion to the approval of Ivy, but the schedule shows that an approval in itself does not trigger immediate progress. A longer start-up period with testing, preparation, and interaction between vessels is included before work on the seabed can begin.
Delays costing billions
Prior to the actual immersion, the schedule shows a longer preparatory phase. This includes, among other things, the establishment and completion of anchor piles for mooring vessels, testing and preparation of equipment, as well as preparation and cleaning of the tunnel trench on the Danish side. Only when these activities are completed can the immersion begin.
At the same time, there is still disagreement about the quality of the tunnel trench. The trench has been excavated by another contractor consortium and subsequently handed over to the client. However, Femern Link Contractors has refused to approve the trench and points to defects and deficiencies, including irregularities and deviations from the design level. The question of whether the trench meets the contract requirements remains unresolved.
The delays already have significant economic consequences. According to the contractor consortium, the cost of the delays could run into double-digit billions, while the client and the state reject that the basis for such claims is documented. At the same time, negotiations are ongoing about who bears responsibility for the various bottlenecks in the project.
