Thanks, @monochrome!
These locks are called Prinses Beatrixsluizen (after our queen mother), opened in 1938, and situated in Vreeswijk. They are the largest inland locks in the Netherlands and on a very busy waterway, the Lekkanaal, the shipping connection between the river De Lek and the Amsterdam-Rijn canal, which is the main route between Amsterdam-Rotterdam and Antwerp. It turned into a bit of a bottleneck with waiting times running into hours. It was then decided to add a 3rd lock. As the locks themselves are considered a historic site of which the look should remain intact as much as possible, the new lock uses roll doors rather than lift doors. The old lift doors were replaced by new ones. The new roll doors (4 in total) were built in China and transported to the NL by boat; they are 28 metres long, 14 metres tall, 6,25 metres thick and weigh 490,000 kgs each (here's one of the new doors:
Gigantische sluisdeuren vanuit China onderweg naar Nieuwegein | RTV Utrecht ).
And here's a timelapse of the doors being put in place:
Timelapse: zo zijn de deuren van de Beatrixsluis geplaatst | RTV Utrecht . And, finally, here's a picture of the way it looks now - the new lock with the roll doors on the right, the original locks on the left:
Prinses Beatrixsluis draait op volle sterkte, alle kolken zijn open | RTV Utrecht
I must admit: I've learnt a lot about these locks myself today, hahaha.