Storm Surge Barrier

Rotterdam, the Netherlands
More than half the Netherlands lies below sea level, and the little country is protected from flooding by about 750 miles (1,200 kilometers) of dikes. The process of global warming and the consequent rise in sea levels will challenge their adequacy, and many of them will need to be raised and reinforced. The extensive Deltaworks project, completed in 1986, secured the province of Zeeland by sealing off its sea inlets. Its northern neighbor, South Holland, remained under threat. Responses to disastrous floods in 1953 had included plans to raise the dikes in the region, but by the 1970s there was public resistance to a scheme that entailed demolishing many historic precincts. The alternative was the construction of a movable storm surge barrier in the man-made approach to Rotterdam Europoort. It is the busiest harbor in the world, and an average of ten ships pass through the New Waterway every hour. Technological and economic feasibility studies led to the construction of the Storm Surge Barrier, one of the engineering marvels of the late twentieth century. Otherwise known as the Maeslant Kering, it is located between the Hook of Holland and the town of Maassluis, a little under 4 miles (6 kilometers) from the North Sea. Built at a cost of 1 billion guilders (U.S.$500 million), it was opened on 10 May 1997. In response to the Dutch governments call for submissions, the Bouwkombinatie Maeslant Kering consortiums tender was accepted from among six competitors. Contracts were signed in October 1989, and the first pile for the hinge foundation was driven in November 1991. The barrier has a guaranteed life of 100 years. It consists of a pair of 50-foot-thick (15-meter) hollow, arc-shaped steel gates, each 73 feet (22 meters) high and 700 feet (210 meters) long and weighing 16,500 tons (15,000 tonnes). Each is attached by means of 795-foot-long (238-meter) latticed steel arms to a steel ball joint seated in a massive concrete socket on the riverbank. The 33-foot-diameter (10-meter) ball joints each weigh 760 tons (690 tonnes) and work with a tolerance of 0.04 inch (1 millimeter). The figures are almost meaningless, but in terms of comparative size, each half of the barrier the gate, the two three-dimensional trusses, and one ball joint weighs as much as two Eiffel Towers. Normally, the gates are parked