ZEEBRUGGE – Lantis and contractor TM COTU* have flooded the construction dock in Zeebrugge, marking a significant milestone for the Scheldt Tunnel project. Over the past two years, intensive work has been carried out in the dock on the eight enormous tunnel sections of the Scheldt Tunnel. These concrete structures, each as large as a football pitch, are now technically ready for the next stage in their impressive journey: their departure for Antwerp. There, in 2030, they will enable a new crossing of the Scheldt, a crucial link in completing the Antwerp ring road. The Scheldt Tunnel is a key project within the Oosterweel link, which will ensure safer traffic, smoother mobility and a stronger Flemish economy.
On Thursday 10 April, the floodgates were opened for the first time at the Zeebrugge construction dock, the home port of the eight tunnel sections of the Scheldt Tunnel. The construction dock is approximately 900 metres long and 150 metres wide. The dock is now slowly filling with up to 800,000 m³ of water – a process that will take about a week.
A symbolic turning point
“The filling is done step by step,” says Bert Claeys, project manager at Lantis. “We are deliberately keeping the filling process slow and under control. This allows us to inspect the tunnel sections regularly for any leaks. Once the dock is completely submerged, the tunnel sections disappear from view. It’s a special moment, as it’s one of the last times we’ll be able to see the tunnel sections we’ve worked so hard on.”
The next step is to remove a section of the embankment so that the tunnel sections can leave the construction dock. This will only happen once the dock is completely filled with water. “That might seem strange,” explains Claeys, “but that sequence was chosen deliberately. By filling the dock first, we create a water buffer. That way, the canal water does not rush in suddenly and uncontrollably when we open the dyke, and everything proceeds safely and in a controlled manner. We took the same approach with the dyke breach on Linkeroever.”
A technical feat
The tunnel sections must not only be watertight, they must also be able to float and sink. This is important for their transport and for the moment they are lowered into their final position in the Scheldt. Over the past few months, each tunnel section has therefore been fitted with five ballast tanks: two large tanks of 3,000 m³ and three smaller tanks of 1,000 m³. These tanks are connected to a piping system to precisely control the weight and buoyancy of the tunnel sections. Whilst the construction dock was being filled, the ballast tanks were also filled with water. This ensures that the sections remain stable on the seabed until they are moved.
Ready for the next stage: the journey to Antwerp
Flooding the construction dock marks the start of a new phase for the project. The tunnel sections, each larger than a football pitch and weighing up to 60,000 tonnes, are ready to begin their journey of more than 100 kilometres towards Antwerp. According to the current schedule, the first tunnel section is due to depart on 19 May 2025.
Each tunnel section will take approximately 30 hours to travel from Zeebrugge to the Doeldok in Antwerp, with stopovers in the outer harbour of Zeebrugge and in Terneuzen to wait for the tide. The sections will remain in the Doeldok until they can be lowered into position around slack water, a time that occurs only twice a month. The schedule is therefore heavily dependent on tides and weather conditions. The first sinking is scheduled for early July; by the end of 2025, all eight tunnel sections should be in place.
New Scheldt Tunnel completes the Ring
The Scheldt Tunnel consists of two tubes for motor traffic, a six-metre-wide cycle tunnel and an emergency tunnel. The tunnel provides an additional crossing beneath the Scheldt and will thus help to complete the Antwerp Ring Road. By improving traffic flow, the Oosterweel link will boost the Flemish economy and make travel safer.
Motorists will be able to drive through the Scheldt Tunnel by 2030, whilst cyclists will be able to cycle through it as early as 2028. The entire Oosterweel link will come into service in 2033.
*TM COTU stands for Temporary Partnership for the Oosterweel Tunnel. The consortium comprises the Belgian construction groups BESIX, Stadsbader Contractors, DEME and Jan De Nul.
