Precision work: Renovation Weir Ensemble Nederrijn (RWEN)

Mennens repairs steel wire ropes at Driel weir, as commissioned by Rijkswaterstaat

Mennens has been involved in the renovation of the Lower Rhine and Lek weirs for several years. The three weir complexes at Driel, Amerongen and Hagestein were due for a renovation after 50 years. Mennens replaces the 1500 kg steel wire ropes and performs various internal quality tests, in line with NEN 3560. Read how our mechanics show an extraordinary example of precision work. 

The weir and lock complex at Driel is one of three weirs in the Lower Rhine, which regulate the water level of the river together. The three weirs consist of two gates, each weighing 400 tons. Each weir has an operating tower topped by a huge winch with four steel wire ropes. These wire ropes realize the vertical movement of the gates, ensuring that they can be raised and lowered. 

Extreme conditions

It’s essential that the steel wire ropes are in good condition. Because at extremely high tides, the gates need to be able to rise all the way up to allow ships to pass. That is why replacement was necessary.  

End of the technical life span

The technical life span of steel wire ropes in locks (and bridges) is 12 to 15 years. The wire ropes in these weirs haven’t been replaced since they were built in the 1960s, so they’ve been in the weirs for 50 years. About time to replace these steel wire ropes.

Specialized craftmanship required for installation

The steel cables weigh 1400-1500 kg each, have a diameter of 66 mm and are 50 meters long. Installing these steel wire ropes in an existing lock therefore requires specialists. Especially when it concerns 16 wire ropes per weir. In new buildings, the roof of a lock is open, and we can lower the cables relatively easily. This is not possible with existing building. We need to be inventive. 

We have therefore developed specially adapted auxiliary tools for this project. Our mechanics have extensive experience with similar projects and modified tools. They can therefore carefully install the new steel wire ropes. 

Quality control in steel wire rope laboratory

The steel wire ropes must undergo various quality controls in line with NEN 3560 before installation. These checks are performed in the steel wire rope laboratory of Mennens Dongen. First, we take a piece from a closed wire rope. We do a torsion test (test for toughness), determine the zinc weight and a breaking test on the various wires in the steel wire rope. Additionally, we break the entire rope on a tensile test bench to demonstrate that the actual breaking load is higher than the minimum breaking load. 

Additional requirements Rijkswaterstaat

Moreover, Rijkswaterstaat (Directorate-General for Public Works and Water Management) requires that the steel wire ropes are pre-stretched for 48 hours at one-third of the minimum breaking load. We used a pre-stretching machine with an effective length of 155 meters, which can put 200 tons of prestress on the wire rope at double effort. In doing so, Mennens meets the high demands of Rijkswaterstaat. 

Plan for replacement

The replacement is now complete, which means the steel wire ropes can last another 50 years. Mennens remains continuously involved in the inspection and maintenance of these steel wire ropes. 
 

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