On Wednesday February 22, Mammoet safely moved the first of three concrete bunkers by the Lek Channel near Vreeswijk, the Netherlands. The project, commissioned by Sas van Vreeswijk (Besix, Heijmans, Jan de Nul) and Rijkswaterstaat, drew a lot of attention from local residents. More than 2,000 people came to witness the operation. Rijkswaterstaat is currently working on widening the Lek Channel and the bunker is the first in a series of historical objects that need to be moved to make way for the shipping lane.
More than 2,000 people came to witness the operation.
Moving the bunker
Mammoet used a gantry placed on Self Propelled Modular Transporters – or SPMTs- to move the bunker. The gantry was put in place a few weeks ago to support the weight of the bunker, allowing contractor Sas van Vreeswijk to disconnect the building from its foundation. After the bunker was detached, Mammoet was able to transport the 1200-ton structure 150 meters to its new location.
At its new location, the bunker was turned and positioned onto the new foundations at an angle. This was done intentionally, because Rijkswaterstaat wants to avoid creating an impression that they were altering history. It was therefore placed into the landscape as an ‘Objet Trouvé’- an object found by an artist and displayed with minimal alteration as a work of art. Mammoet used a combination of a skidding system and four strand jacks to rotate the bunker. By lowering two strand jacks while two other strand jacks held still, the bunker could be rotated while its center of gravity remained stationary.
The project was a challenging assignment for Mammoet. The bunker was designed to withstand bombing raids, so our client had to bring in a special drill that could drill through the reinforced concrete, enabling it to be attached to the gantry. The team also had to create a road between the old and new locations to ensure that the transport would not get bogged down in muddy ground during the operation. In addition, the bunker had to be positioned at an angle, to highlight to everyone who passes the bunker that it has been moved. “This required teamwork and precision down to the smallest detail,” says Ruud Jansen, Commercial Manager at Mammoet. He is proud that the project was executed perfectly. “It’s really a circular project, from old to new - taking something and giving something back.”
The bunker was part of the Nieuwe Hollandse Waterlinie, a series of works constructed before World War II that were designed to defend the Netherlands against foreign invasions. Because the bunker is an important piece of historical heritage, Rijkswaterstaat wanted to move the heavy concrete building in one piece. The bunker is not the only object that will be moved to make way for widening the channel. In total, Mammoet and Sas van Vreeswijk will be moving three bunkers and two water management structures during the upcoming months.