Denmark’s largest construction project enters new phase as first tunnel section lowered to seabed

The first concrete segment of the 18-kilometre Fehmarn Belt immersed tunnel—the largest infrastructure project in Danish history—was lowered onto the seabed near Rødbyhavn on Wednesday, marking a major milestone after two years of delays, reports Danish broadcaster DR.

Weighing 73,000 tonnes—equivalent to over 560 blue whales—and stretching 217 metres (roughly two football pitches), the massive structure is the first of 89 identical elements that will form the submerged link to Puttgarden, Germany. Specialised vessel IVY guided the segment into position, a manoeuvre expected to take up to 11 hours.

“This is the culmination of years of hard work for so many people,” said Anders Wede, construction area manager at state-owned developer Sund & Bælt. “We’ve all been looking forward to this moment.”

Vice contract director Lasse Vester called the operation “a huge relief and a tremendous milestone,” noting he had worked on the project since 2012. Delays stemmed from technical challenges with IVY, which received final approval only on 1 April.

Weather conditions, precise positioning, and system checks were critical prerequisites, Wede added. “Safety is our top priority. We need to hit the right weather window and ensure everything functions before proceeding.”

The €7.4 billion tunnel, set to open in 2029, will replace ferry services between Denmark and Germany, cutting travel time from 45 minutes to seven by train and ten by car. Sund & Bælt will assess the timeline for subsequent immersions before confirming a revised schedule.