The arms of the barrier are a treat to the eye. However, their function is limited: the power exerted on the retaining walls when they are closed is transferred through to the ball-and-socket joints. The ball-and-socket joints are in fact the main figures. Both joints ensure the gates can move in all directions, both horizontally (when sailing out) and vertically (when sinking down). Furthermore the gates must be able to sway on the waves in case of a storm. Finally it must be capable of transferring the enormous water pressure on the gates through to the foundations. The only kind of joint that
is able to follow all these movements, is a ball-and-socket joint. It can be compared to a human hip or shoulder joint. However, the joints of the dam have a diameter of ten meters and weigh 680 tons.
The threshold construction on the bottom of the New Waterway has three functions:
- To form a flat base and strong foundation for the retaining walls, which are moored with buffers onto the threshold blocks.
- To limit the flow of water in the case of a closed barrier.
- To grasp the base on which the blocks are founded.
The movement works are operated from control buildings at the north and south side. The movement works consist of three parts: the dock gate, the locomotive and the ballast system of the retaining wall. The dock gate opens when the barrier is activated. The barrier is driven into the New Waterway by the locomotive. The ballast system allows the barrier to sink.
BOS and BES
The Maeslantkering is operated by a computer. In the case of a storm flood, the decision of whether or not to close the barrier is left to a computer system (BOS). The chance of mistakes is greatly increased if people were to make the decision. A computer will only follow predefined procedures, it doesn’t get
its own ideas and it is not affected by poor environmental conditions. The system only takes into account the water and weather forecasts. On that basis it calculates the expected water levels in Rotterdam, Dordrecht and Spijkenisse. When the BOS decides to close the barrier, it gives orders to another computer system, the BES. The BES carries out the orders of the BOS. The system operates entirely automatically, but remains under constant human supervision with regards to the procedures.