MacArtney Connected First Fehmarnbelt Tunnel Elements
Subsea power and data systems now support the immersion of 73,500-tonne tunnel segments.
Updated on Sept. 28, 2026 in Data Centers
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Construction crews have successfully immersed and connected three of the 89 planned concrete elements for the 18-kilometre Fehmarnbelt tunnel. The deployment marks the operational use of subsea power and connectivity systems developed by MacArtney to manage the massive segments underwater.
Why it matters
The system ensures precise control and monitoring of structural elements during the high-stakes tow-out and immersion process at depths of 40 metres. This capability is essential for managing the installation of infrastructure that must withstand extreme environmental conditions over the life of the tunnel.
Each 217-metre-long tunnel element weighs 73,500 tonnes, requiring specialized Retrieval Frames equipped with cameras and actuators to bridge power and data connections. These frames interface with Bulkhead Connector Plates to provide the necessary control signals at depths of up to 40 metres.
The players
MacArtney
A provider of subsea technology and connectivity systems specializing in harsh-environment electrical and optical connectors for marine infrastructure.
Femern Link Contractors
The construction consortium responsible for the engineering and assembly of the massive tunnel elements across the Fehmarnbelt.
The details
To manage the immersion of each concrete element, MacArtney and Femern Link Contractors utilize Immersion Pontoons named IVY 1 and IVY 2. The Retrieval Frames maintain vital power and connectivity links to the elements until they are securely positioned. Once the element is placed, remotely operated vehicles disconnect the frames for recovery, allowing the immersion pontoon system to repeat the process for subsequent segments.
Timeline
September 28, 2026: Three tunnel elements have been successfully immersed and connected.
The Tech Race
This installation follows the technical requirements set by the Fehmarnbelt tunnel project to connect Denmark and Germany via subsea infrastructure. The successful deployment validates the subsea power and data management systems now critical for heavy-civil marine engineering projects.
This project establishes the technical foundation for future cross-border transit between Denmark and Germany. As the 86 remaining elements are installed, the success of these subsea connectivity systems will dictate the ongoing construction timeline for the link.
The takeaway
The successful integration of these subsea systems demonstrates the viability of modular underwater positioning for massive infrastructure. Observers should track the installation rate of the remaining 86 elements to determine the overall trajectory of the tunnel completion.
Further reading
Learn more about the infrastructure supporting complex connectivity in Data Centers.
Source note: This article includes information reported by Hydro-international.
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