Femern Timeline Crumbles: Danish Delay of Several Years Awaits

On paper, the opening in 2029 still stands as the official goal for the Fehmarn Belt connection. But the large construction project, which is to connect Denmark with Germany, can no longer be completed on time. This is shown by FemernBusiness' review of internal schedules, environmental approvals, noise limits, and status reports. It will require an almost unrealistic acceleration of work at sea to achieve it.

The pace is precisely the key. Without a stable flow of immersions, the entire schedule risks collapsing. And here the project is already significantly behind.

The tunnel itself consists of 89 concrete elements, each weighing over 70,000 tonnes and 217 meters long. According to the original plan, they were to be lowered into place over three years - 36 months - with an average of 2.5 elements per month throughout the year. But the first 18 months have already been lost, and no element is in place at the bottom of the Fehmarn Belt. This leaves only about 18 months to do what should have taken 36. The pace must therefore almost double to over five elements per month. And this in a body of water where the winter months often pause work due to waves and currents, and where new documents show that the summer is subject to strict environmental restrictions.

Everything indicates that the pace cannot be increased, but on the contrary, will be slowed down. And small deviations cause large shifts: With a pace of two elements per month, completion is pushed to May 2029, while 1.5 elements extend into August 2030. And in a scenario with just one element per month, the actual submersion will take more than seven years and will not be completed until January 2033. On top of that, an additional two years of installation and testing work follow before the Fehmarn Belt connection can be opened.

- In reality, it is only the client and the contractor who have the insight into how the schedule looks with the challenges that exist. Having said that, it is no longer a question of whether they will be delayed, but how much they will be delayed, says Kim Haugbølle, senior researcher at the Department of the Built Environment, Aalborg University.

The problem child Ivy 1 and Ivy 2

The delay is not due to a single error, but a combination of technical, administrative, environmental, and logistical factors, each of which limits progress. The core, however, is the approval of two specially built vessels - Ivy 1 and Ivy 2 - which are crucial to the process. These are the ones that must transport the elements from the production port in Rødbyhavn to the precise position on the seabed and place them with millimetre precision. Ivy 1 and Ivy 2 are built specifically for the Fehmarn project at the Crist shipyard in Poland and must be approved by the Danish Maritime Authority, and here problems have arisen. The approval process started in the autumn of 2024 and is not yet completed. 

2,000 sent on holiday

While the approval is delayed, the production of tunnel elements has continued unabated. In May 2024, the first element was completed in the gigantic factory in Rødbyhavn. Since then, the number has grown. Storage capacity is limited to around 15-18 elements distributed between land and water, and when that limit is reached, production cannot continue at the same pace. This is exactly what happened in the summer of 2025, when around 2,000 employees were sent on compulsory leave. Officially to take summer holidays, but in reality because there was no longer space to store more finished elements. So here we have a real bottleneck for the project.

Even if the Ivy vessels are approved within the next few months, there are other limitations that could hinder a quick recovery of the lost time. Large parts of the Fehmarn Belt are designated as a Natura 2000 area - an EU-protected habitat for porpoises and several endangered bird species. On the German side, two central noise limits have been set: Firstly, no more than 20 percent of the belt sea's cross-section may be exposed to noise levels above 144 dB from stationary project work at any time. Secondly, from 1 June to 30 September, no more than one percent of the Natura 2000 area may be exposed to noise above 140 dB. This means that even in periods of perfect weather, work can be paused if the noise limits are exceeded. And the monitoring is strict. The Quonops model, which is used to monitor the noise, calculates the noise distribution throughout the area every quarter-hour based on the vessels' positions, their measured noise sources, and current weather and current conditions. If the limits are exceeded, the work must be changed or stopped immediately.

Cannot work at sea all year round

In Femern A/S's own annual report from March 2025, the company acknowledges that the weather itself is a limitation: "There are only certain periods of the year when the weather makes it possible to lower elements into the open Belt Sea." This means that even without Natura 2000 restrictions, the work will be limited and dependent on good weather, and combined with environmental requirements, the working year is further reduced.

Experiences from other large marine construction projects show that the weather can be just as big a challenge as the formal environmental requirements. The construction of the Storstrøm Bridge has been halted several times by wind, waves, and current conditions. Lowering a tunnel element requires several consecutive days of calm weather - not just a single day - because the process involves towing, precise placement, lowering, and underwater coupling. If the weather window closes in the middle of the process, the work must be stopped and, in the worst case, started over.

The German Bauzeitenplan

According to the internal Bauzeitenplan from 27 May 2025, which FemernBusiness possesses, preparations on the Danish side are well underway. This includes clearing the tunnel trench and preparing the foundation before the actual lowering can begin. It states that the lowering of the first tunnel element is set for September 2025, but does not reveal what the end date will be.

At the same time, documents obtained by FemernBusiness through a freedom of information request show that the practical framework for work in the Fehmarn Belt has become tighter than the contractors originally planned for. According to a presentation to the political agreement circle, the German authorities have reduced the work corridor in the Natura 2000 area to 648 metres in width compared to the 1100 metres included in the contract. Additionally, a so-called 'no spill' requirement applies during the summer months of June, July, and August, where all material from marine work must be completely collected. Both changes mean that the lowering work becomes more complex and time-consuming than the project was originally planned for. Femern A/S itself also describes the lowering of the tunnel elements to the agreement circle as 'the most complex and weather-sensitive work' in the entire construction process.

What does Femern say?

In a written response to FemernBusiness, the Fehmarn Belt project states that the lowering of the tunnel elements will begin when the special vessel Ivy is tested and approved, and it is expected to happen later this year. The project also states that the timeline remains challenged and will be reassessed after the first elements are in place. The goal of opening in 2029 is not mentioned. Instead, the Fehmarn Belt project states that both the German environmental restrictions and delays on the German side will be included in the assessment of when the tunnel can be completed.

The delays on the German side themselves constitute a barrier for the entire project. The entire railway connection depends on a new 2.2-kilometre-long tunnel under the Fehmarn Sound, which is to connect the island of Fehmarn with the German mainland. It is crucial because it links the upcoming immersed tunnel to the existing German railway network. According to a document from the Federal Railway Authority, it will take 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. 

The biggest challenge now lies on the Danish side. It is here that the entire schedule for 2029 is practically slipping. Car traffic could, in principle, be opened if the immersed tunnel under the Fehmarn Belt was completed - and it would also be possible to officially inaugurate the connection and better bind Europe together without a German railway tunnel.

Delays are economically costly

The total construction cost for the Fehmarn connection is set at over 55 billion kroner in 2015 prices. Each month's delay means additional costs for staffing, rental and operation of vessels, contract extensions, and materials that become more expensive. 

And a delay will hit doubly, explains senior researcher Kim Haugbølle.

- A delay will impact both revenue and expenses. It will increase construction costs. And on the revenue side, it will take longer before money comes in.