Preparing the monumental weir at Grave for the future. Mourik Infra worked on this major maintenance project for Rijkswaterstaat together with Swarco, under the name CMD. Replacing the yokes, sliders and crane truck requires technical expertise, innovative working methods, and close cooperation between various Mourik disciplines. This enabled CMD to achieve the Rijkswaterstaat contract milestone and improve safety. A job well done, that deserves the Mourik Excellence Award.
Smart planning with ‘trains’ of work
The weir at Grave has 20 yokes with three sliders each to regulate the water discharge of the Maas River. The replacement of the yokes and sliders was done in a continuous process.
‘This was a very complex project, with the first things already in the works while the designers were still working on the last things. Together we were able to make decisions quickly and effectively to maintain the pace’, says Louis Verhagen, Contract Manager at Rijkswaterstaat.
‘The team developed a ‘train’-based approach so we had a continuous replacement cycle. Every two weeks we would replace a yoke; because we had two teams working simultaneously, we were able to replace a yoke each week without having to compromise on safety. That way, we were also able to stick to the planning schedule despite the challenging circumstances’, says Ivo Thuijls, project manager at Mourik Infra.
The conditions were not always ideal. The water levels and discharge determine whether work is possible. A weir is also a monument, meaning everything has to respect the applicable historical context. Ivo: ‘We had a strict deadline, namely the end of 2024, for replacing the yokes and sliders, but at the beginning of that year, the water discharge was too high to start. We wanted to start in April, but in the end we were only able to in mid-May. We were nonetheless able to achieve our objectives with smart planning and good cooperation. Compliments to the team!
‘In a regular process, such lead times are unthinkable. Everyone took responsibility, which ensured that everything went seamlessly,’ says Paul Swaneveld, Asset Manager at Rijkswaterstaat ZN.
Automatic and safe lifting of the yokes
An innovation was also used for the way in which the yokes are lifted at high tide. Previously, this used to be done with a crane truck, which involved a lot of manual work and the associated risks; now this process has been fully automated by giving each yoke a new drive. ‘The yoke can now be lifted at the tap of a button. This is a huge step forward in terms of safety,’ Ivo explains.
In addition to the yokes and sliders, in 2025 the weir will be fitted with new slider drives, yoke drives and a new crane truck that will move the yokes horizontally against the underside of the bridge. The entire operating and control system will also be renewed and housed in a new E-room.
The collaboration between Mourik Infra, Mourik Techniek, Swarco and various departments of Rijkswaterstaat ensures that design choices are made quickly and are widely supported. ‘This project shows that if you select a good contractor, you can trust them to do their job well without having to constantly ask for details. A process that Mourik, Swarco, and we at Rijkswaterstaat are all proud of, both in terms of the collaboration and the results,’ says Louis.
The project won the Mourik Excellence Award, an annual award for exceptional performance within Mourik. Ivo: ‘We achieved the milestones we set together for a technically complex project in a challenging environment. Something we're definitely proud of.’
‘We achieved the milestones we set together for a technically complex project in a challenging environment. ’
