Car in the water
Between the 1920s and the 1950s, more and more cars appeared in Amsterdam. And every now and then those cars had to park along the quays of, say, the Herengracht or the Prinsengracht. There were no parking sensors, let alone a reversing camera, and the handbrake was sometimes forgotten too, so it happened regularly that cars made a little mistake while parking and ended up in the canal. The wrecks were then hauled out of the canal by the fire brigade or a towing company, often in front of a large crowd. With all the damage that entailed.

The solution: a low railing
Around 1954 the city council decided it was time to do something about the cars in the water. The accidents created unsafe situations, and meanwhile ever more cars were taking to the road. It was decided to drill an iron bar into the quay wall, standing about 20 centimetres above the ground. The Herengracht had the honour of going first, and most other quays followed later. It proved an effective measure: the railing ultimately led to far fewer cars in the water.
Still take care
The railing was installed along most of the canals, but certainly not everywhere. Along the Reguliersgracht, for example, you will still find many stretches without the protective iron bar. So watch out! And yes: even with a low front bumper you should not drive too far forward, that can cause nasty damage.