In a few weeks' time, the eight imposing concrete elements of the Scheldt Tunnel will begin their journey from Zeebrugge to Antwerp. This marks a major milestone in the Oosterweel project, where BESIX – as part of the TM COTU consortium – is helping to deliver this vital component of Antwerp's transport infrastructure.
Dry dock in Zeebrugge now underwater
For the past two years, TM COTU has been constructing the eight tunnel elements for the Scheldt Tunnel in a specially designed construction dock in Zeebrugge. Each element weighs 60,000 tonnes and measures 160 metres in length, 42 metres in width and 10 metres in height. That is larger than a football pitch, exceeds the length of Belgium's tallest cathedral, and stretches the equivalent of five whales placed end to end.
A crucial preparatory step was taken in mid-April when the dry dock, measuring 900 metres by 150 metres, was carefully flooded. This operation required approximately 800,000 cubic metres of water – equivalent to filling 320 Olympic swimming pools.
Engineered to float using ballast technology
To facilitate transport, each element has been equipped with five ballast tanks - two large ones of 3,000 m³ and three smaller ones of 1,000 m³ each. Currently filled with water, these tanks keep the elements securely positioned on the dock floor. Once the water is pumped out, these colossal structures will float to the surface, ready to be towed.
100 kilometres across the North Sea and Scheldt
The transport operation will begin on 19 May, with the elements being moved individually by tugboats along a route spanning over 100 kilometres through the North Sea and the Scheldt River to Antwerp. This remarkable journey will take approximately 30 hours per element.
Each element will make two stops along the way – one at Zeebrugge's outer harbour and another at Terneuzen – where the elements will wait for high tide to utilise favourable currents. If all goes according to plan, the first immersion operation in Antwerp will take place in early July. By the end of the year, all eight elements will be in their final position beneath the Scheldt.
A masterpiece of logistics
This large-scale logistical operation presents numerous technical challenges. From the controlled transport across the North Sea and the Scheldt to the precise underwater placement – each phase requires thorough preparation and collaboration between multiple stakeholders.
The planning is also dependent on numerous environmental factors such as weather conditions, wind strength, wave height and tides. Through advanced simulations, TM COTU has been able to meticulously map the entire route and prepare for the various circumstances.
Completing Antwerp's Ring Road
The Scheldt Tunnel is an essential link in the Oosterweel connection and will complete the Antwerp Ring Road on the northern side. It will initially open to cyclists in 2028. From 2030, the tunnel will also provide a crucial link for vehicles and lorries between the motorways on Antwerp’s Left Bank and both the port and northern part of the city.
TM COTU consists of BESIX, DEME, Jan De Nul and Stadsbader Contractors. In addition to the Scheldt Tunnel, BESIX Group is also involved in the Canal Tunnels and the sunken Ring Road section as a member of the ROCO consortium.