According to a status report, the tunnel trench cannot be approved. The main contractor warns of serious deficiencies, and the first tunnel element can only be submerged in May 2026.
The tunnel trench is where the many elements must be placed for Denmark to be connected with Germany.Femern A/S
Amidst the reports that the first lowering of the tunnel elements is just around the corner, internal documents show a completely different picture. The tunnel trench, where the 89 elements are to be placed, is not approved. In the status report from July this year, which FemernBusiness possesses, the earliest time for the lowering of the first tunnel element is set for 9 May 2026. This is more than two years after the original schedule.
The internal papers thus paint a much more uncertain picture than what Femern A/S officially announces.
- It is not uncommon to have two narratives running simultaneously. The internal and the external. Outwardly, they maintain that they will open in 2029. Inwardly, we have some papers from the very heart of the operation that show a different reality than what is told to the public, says Kim Haugbølle, senior researcher at the Department of the Built Environment at Aalborg University.
How much difference can there be in the two narratives?
- This is quite a significant deviation, says Kim Haugbølle.
The fact that the trench is now becoming a problem adds to a series of major challenges in a construction project on the Danish side that is already struggling with vessel approvals and strict German environmental requirements.
The status report from FLC to Femern A/S and Sund & Bælt.
According to the documents, the actual transfer of the tunnel trench has been put on hold. The transfer is a formal shift, where responsibility goes from the client Femern A/S to the contractor Femern Link Contractors (FLC), but it can only occur if the trench meets the established requirements. According to the status report, it does not.
The documents reveal that the data about the tunnel trench provided by Femern A/S is unusable. Therefore, the main contractor FLC has examined the first 650 metres of the 18-kilometre-long tunnel trench and found such significant deficiencies that it concludes the trench does not meet the necessary standards.
It is also stated that the date for lowering the first tunnel element on 9 May 2026 is tentative - that is, provisional. According to the internal report, the timing of the first submersion depends on a possible redesign of the foundation in the tunnel trench, which could further delay the timing.
Sund & Bælt, which is behind Femern A/S, denies that the problems with the tunnel trench will alter the schedule. According to press officer Jens Villemoes, the contractor consortium FLC has had access to the trench since the summer of 2024 on the Danish side and from 1 November on the German side, and it has always been the plan for FLC to adjust the trench before submersion. The latest geotechnical surveys have shown that parts of the trench have been dug slightly deeper than planned, but according to Villemoes, this can be compensated for by laying a thicker layer of gravel under the elements.
- The process is as expected, although with a greater need for adaptation of the tunnel trench than initially assumed. The ambition remains unchanged that the first submersion will occur later this year. However, the timing is fraught with great uncertainty due to the complexity of the process, he says.
Consequences for production
The problems with the tunnel trench do not stop at technical discussions between the client and the contractor. They directly impact production in Rødbyhavn, where the enormous concrete elements are cast. Each element is over 200 metres long and weighs more than 70,000 tonnes, and the factory is set up for constant operation. Once the elements are finished, they must either be placed in the sea or temporarily stored on land and in the basins at the factory.
But storage capacity is limited. When the trench is not ready, they cannot be submerged, and thus elements accumulate in Rødbyhavn. The status report from July warns that this problem will only grow as long as the tunnel trench cannot be approved. Temporary storage in the harbour basin has already been utilised, and the report points out that tunnel production is already affected by periods of standstill, which can further impact the schedule.
The Ivy vessels are still missing
For the actual submersion of the tunnel elements, the two specially built vessels Ivy 1 and Ivy 2 still need to be approved. They are made for the Femern project and designed to handle the heavy elements with millimetre precision. However, the vessels have not yet been approved by the Danish Maritime Authority. The technical assessment is with the Norwegian company DNV, and the work has been delayed. Femern A/S has repeatedly stated that approval is expected “later this year”.
Environment and Weather as Obstacles
When both the trench and vessels are ready, the next barrier awaits: environmental requirements and the weather. Large parts of the area are designated as Natura 2000, and strict noise limits apply here. No more than 20 percent of the belt's cross-section may be exposed to sound pressure over 144 decibels, and in the summer months, only one percent may exceed 140 decibels. By comparison, porpoises emit clicks of up to 170-180 decibels, but in short, directional signals. The construction site's machinery, on the other hand, creates constant background noise, which can disturb the animals. Therefore, the Quonops model continuously measures noise distribution, and work must be stopped immediately if the limits are exceeded.
In addition to the environmental requirements, there is the weather. Femern A/S has acknowledged that it is only during certain periods of the year that the weather permits lowering.
Pace and Schedule
It is precisely the weather and noise limits that make the pace uncertain. The noise limits apply in the summer when conditions are normally most optimal, while the weather makes it difficult in the winter months. The plan is for the 89 elements to be lowered at a pace of 2.5 per month - a total of 36 months. If starting in May 2026, as the report now suggests, the last element will ideally land in May 2029. Adding two years of installation and testing, this points to an opening in mid-2031.
If the pace slows down, the dates will be adjusted accordingly. At a pace of two elements per month, the work will extend into 2030, with 1.5 elements all the way to 2031 - and in a scenario with one element per month, not until 2033.
On the German side, there are also factors that can affect the overall schedule - but only the train traffic. It depends on a new 2.2-kilometre-long tunnel under the Fehmarn Sound, which will connect the island of Fehmarn with the German mainland. According to a document from the Federal Railway Authority, it will take about six and a half years from the granting of the building permit until the tunnel is ready. Since the permit has not yet been granted, construction has not begun.
