Schinkelbrug to get state-of-the-art deck

The new moveable bridge elements – four in total – are all being manufactured by Solidd Steel Structures in Friesland. They will become part of what is known as a bascule bridge, which is the same type of bridge as the existing five bridges. However, as technical manager Joop van der Velden of Zuidasdok explains, that does not mean we can simply carry out a cut and paste operation: ‘Rijkswaterstaat manages around 160 moveable bridges. We are now using all that knowledge and experience for the new Schinkel bridges – and more.’

The deck will be affixed from the bottom by steel profiles welded diagonally in the form of a grid. This involves thirty-three ‘troughs’ running lengthways, and five cross supports, known as ‘crests’. Van der Velden: ‘Even before the troughs were affixed, the welded sections were around one kilometre in length. That’s because we sometimes weld three or four layers on top of each other – yet another example of the new and more stringent standards we are applying to the Schinkelbrug.’

When the bridge is completely closed, then the deck and the counterweight are fully in balance. To move the deck, the mechanism requires a ‘nudge’. This is provided by an electric engine located in the bascule basement (where the bascule mechanism is incorporated), which sets off a cogwheel. This three-metre high cogwheel is attached to the bridge deck via a shaft and pushes the bridge upwards. An interesting system, believes Van der Velden: ‘The cogwheel is not completely round. This means the initial speed is slow, but there is still lots of energy available to get things moving. The counterweight then does its work until the deck is again slowed down by the cogwheel at the end of the cycle.’

Our Friesian steel manufacturer is supplying all the components for the bascule bridge: the deck, the axle, the ballast containers, and the mechanism with the cogwheel. Steel products of this kind are never ‘off the shelf’; as Van der Velden explains, they have to be made to measure because every bridge is different. ‘That’s why some components were ordered as long ago as the summer of 2024, even though we will not be putting them in place until 2027. The cogwheels are also coming a long way – they are being built in France.” The Dutch term for these cogwheels is ‘Panamawiel’. Are they not being built in Panama? Van der Velden laughs: ‘The name comes from the fact that this type of mechanism was first used on the Panama Canal.’

The first deck (for bridge 9) will be transported in its entirety from Friesland to the Schinkelbrug in or around May 2026. As Van der Velden explains, this will be a spectacular event: ‘The deck alone is too big to be transported by road, so the manufacturer is bringing it by boat.’