The Prins Claus Bridge: unique in appearance and operation

The Prince Claus Bridge is a steel bicycle and pedestrian bridge between Dordrecht’s Stadswerven district and the historic city centre. During the annual Steel Construction Day, this bridge won the National Steel Construction Prize in the Infrastructure category. This article explores why this royal bridge has already earned an award to its name just one year after its official opening.

René van Zuuk Architects composed the architectural design and transformed the bridge into an architectural eye-catcher. Commissioned by the Municipality of Dordrecht, the execution was conducted by a construction consortium consisting of Dura Vermeer and Hillebrand. Engineering company Iv-Infra developed the architectural design into an integral final and implementation design.

Playing with the laws of nature

A unique system
Princess Beatrix opened the Prince Claus Bridge in the autumn of 2021. The bridge forms an essential link in the future fast cycle route between Dordrecht’s historic centre and the Merwelanden, Papendrecht and Sliedrecht. It spans 141 metres and consists of two approach ramps and a movable section of almost 50 metres. The unique part of the Prince Claus Bridge is that it spans the waterway diagonally: a challenge for the expansion joints during the structural design phase, whereby the margins were much tighter than with regular bridges. The bridge is hydraulically powered. The movable deck is balanced around the pivot axle with a unique system comprising a hinged counterweight pylon held upright by a pendulum.

In a nutshell: playing with the laws of nature. As a result, an impressive bridge with a never before applied movable system has become an iconic landmark for Dordrecht.

The reference design by architect René van Zuuk can rightly be referred to as ambitious

Britte van Kortenhof of Iv-Infra participated in the project as Design Manager. One of the most challenging projects, as far as she’s concerned. “During the elaboration of a feasible, maintainable and reliably functioning technical design, all components were intensively coordinated to satisfy the strict design requirements. The architectural concept was binding. A beautiful bridge, but with incredibly tight margins.”

Magnificent solutions for challenging issues Iv-Infra had to work with an accuracy (tolerance) of 5 millimetres. “This made such a project quite a challenge and, above all, extremely critical. But also fun! We love to work on complex projects. We have many creative designers within Iv-Infra who can devise magnificent solutions for challenging issues.”

Everything to do with the Prince Claus Bridge revolves around its high-quality finish and flowing movements

The reference design by architect René van Zuuk can rightly be referred to as ambitious. Firstly, because of the appearance. All pivot points and movable sections of the bridge are entirely concealed under hoods that merge with the adjacent structural components. But this initiative can also be observed on a mechanical level. The bridge opens and closes flowingly, with which the counterweight pylon moves towards the movable deck upon opening. Both reach a standstill at an angle of 85 degrees. When the Prince Claus Bridge closes, the counterweight pylon and the movable deck remain in cohesion for the first 45 degrees of closure, after which the counterweight pylon rises. Like choreography.

The mechanism
The movable deck, counterweight pylon and pendulum move as a single mechanism. The counterweight pylon is connected with pivot points to the main girders of the movable deck. When the movable deck begins to move, the pivot point of the counterweight pylon revolves in a circle around the main pivot points. The pendulum holds the counterweight pylon upright and is coupled to the counterweight pylon via the upper pivot point and at the bottom to the approach ramp by another pivot point. As a result, the pendulum exerts both horizontal and vertical load on the lower pivot point.

Pivot points
Everything to do with the Prince Claus Bridge revolves around its high-quality finish and flowing movements. The movable sections of Dordrecht’s Wantij crossover are hinged to the fixed parts of the bridge. Upon opening and closing, the moving sections revolve around six pivot points: two on which the movable deck revolves and two with which the underside of the counterweight pylon is connected to the rear of the movable deck. Further to these is the pivot point that connects the top of the pendulum to the counterweight pylon and, finally, one that connects the pendulum to the eastern approach ramp.

The design of these pivot points was not universal: each has a unique specific application with associated integration problems, with which the points were implemented differently. In addition, the two pivot points connecting the movable deck to the concrete chamber are fitted with self-aligning spherical roller bearings: a robust and heavy-duty type of roller bearing, a necessary measure due to the high load exerted on these pivot points.

This also applies to the pivot points that connect the counterweight pylon to the rear of the movable deck. These points almost entirely support the 300-tonne weight of the counterweight pylon and are also equipped with self-aligning spherical roller bearings.

The lower cylinder of the award-winning bridge is provided with a special coating suitable for underwater use

The pivot point between the counterweight pylon and the pendulum is subjected to less stress, which is why a less maintenance-sensitive bearing was chosen in this design: a spherical plain bearing with a fibre-reinforced plastic liner. The fourth variant concerns the pivot point between the pendulum and the approach ramp, where a spherical plain bearing was also used due to the relatively low bearing forces. Just as with the uppermost pivot point, the ends of the axle are concealed behind removable steel covers.

High water resistance
Both hydraulic cylinders of the bridge can be seen and are therefore configured outside of the chamber. From the bridge’s eastern side, the working of the cylinders is clearly visible and can be observed during opening and closing. Should the water level of the Wantij be (incidentally) high, both the chamber floor and the cylinder feet supported by the chamber floor may become submerged. Therefore, the lower cylinder of the award-winning bridge is provided with a special coating suitable for underwater use. In addition, the pivot point on the underside is equipped with a double seal and is filled with grease. The lower cylinder pin will not be negatively impacted if the bridge becomes partially submerged for an extended period.

The architectural design combined with Iv-Infra’s technical elaboration and execution were reason enough to nominate this unique bicycle and pedestrian bridge and ultimately crown it as the winner. •

Would you like to know more about the Prince Claus Bridge? Pieter will be pleased to tell you more. Contact him via 088 943 8332 or send Pieter an email.

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