Antwerp – The Scheldt Tunnel project has encountered a significant delay due to the discovery of a 5,000 m³ sandbank obstructing the sinking of the 4th section. Lantis anticipates a delay of approximately one month, while the completion of the full Oosterweel connection remains scheduled for 2030, reports 24brussels.
As VRT News reported, the failure to sink the 4th section of the Antwerp Scheldt Tunnel has resulted in a substantial setback. The sandbank, measuring around 5,000 m³, equivalent to approximately 200 truckloads of sand, was found precisely at the site designated for lowering the tunnel segment.
The first three immersions had proceeded without issues. Each phase of the operation requires extensive planning, and engineers even developed a model of the Scheldt in a test basin in the UK to rehearse the procedure.
“The Scheldt’s bottom is made up of sand waves that can reach heights of up to 3 meters,”
explains Meire.
“These waves move back and forth under the influence of the current. During a single tide, the crest of such a sand wave can easily shift several meters.”
What caused the delay in the Antwerp Scheldt Tunnel 4th section project?
Experts indicate that the riverbed of the Scheldt is in a constant state of flux, complicating predictions and control. Sediments and sand are influenced by tides and currents, making it impossible to guarantee accuracy through data or simulations.
Patrick Meire acknowledges that such unexpected occurrences are common when working with natural river systems. Lantis spokesperson Laure Stuck described the development as a bitter disappointment but acknowledged that even meticulous preparations cannot eliminate all risks inherent in large-scale projects.
“A sandbank suddenly appeared overnight, comparable to 200 truckloads of sand.”
Laure Stuck van Lantis
Meire reassures that the emergence of a 5,000 m³ sandbank during the tunnel’s sinking is within the realm of expectations. He points out that placing such a significant structure in the Scheldt presents substantial challenges.
Meire warns that no technology can predict every alteration in sand and water movements.
“It is a huge operation,”
he affirms.
“The bottom changes constantly, the current is strong, and nature still decides more than humans.”
“After that initial disappointment, it’s now all hands on deck,”
she says.
“Not only in analysing what went wrong, but also in how we can solve this problem. We’re still considering whether to move the tunnel section underwater or remove it first,”
says Laure Stuyck of Lantis.
Lantis is currently evaluating the failed attempt step by step. Engineers are investigating the reasons behind the sandbank formation at that location. Stuck confirmed that the tunnel section will remain underwater for an additional two weeks until the next neap tide, when conditions are expected to improve. The project schedule will be delayed by about one month, but work will proceed.
Plans for the Oosterweel connection originated in the 1990s, when Antwerp’s traffic congestion and incomplete ring road were recognized as significant economic issues. The initial proposals instigated decades of discussions, legal disputes, and citizen protests concerning environmental concerns and local neighborhood impacts.
After years of political stalemate, a resolution was reached in 2017 with the “Oosterweel deal,” an agreement between the Flemish government, the city of Antwerp, and community action groups. Construction of the Scheldt Tunnel, the most technically challenging aspect of the project, officially commenced in 2021, with the first tunnel segments successfully immersed in 2024. The complete connection is projected for completion by 2030.
