docks. When the hollow gates start to float and the water level in the dock reaches that in the New Waterway, the dock gates are opened. The “locomobiles”—their name explains the function—on top of the gates push them horizontally out of the dock into the Waterway. The gates meet in the middle, not quite touching. They are then flooded and slowly sink to the concrete sill on the bottom of the Waterway, 56 feet (17 meters) down. The ball joints move in differrent directions following the gates’ movements: horizontally (when the gates are floated out) and vertically (upon submersion). The gates must be able to ride with the waves when being closed and opened. In a fierce storm, the water could hit the barrier with up to 33,000 tons (30,000 tonnes) force. The loads on the structure are transmitted to the 57,000-ton (52,000-tonne) triangular concrete foundations of the ball joints. After the storm the gates are floated again and driven back into the dock by the locomobiles. The dock gates are closed, and the dock is pumped dry. From the time the computer registers the need to close the barrier until the gates are in place, the operation takes nine and a half hours. After the storm, it takes two and a half hours to return the gates to their docks.

It is expected that the barrier will have to be closed (on average) once every ten years, but changes in sea levels over the next half-century may double that. Seawater can enter the Europoort area freely through other waterways, and a supplementary dike-reinforcement program is being implemented, with a further defense known as the Europoort Barrier acting to support that in the New Waterway.

See also

Afsluitdijk; Deltaworks

Further reading

BMK (Bouwkombinatie Maeslant Kering). 1997. Sluitstuk van de Deltawerken; Stormvloedkering Nieuwe Waterweg. The Hague: Ministerie van Verkeer en Waterstaat.

Kerssens, P. J. M., et al. 1989. “Storm Surge Barrier in the Rotterdam Waterway: A New Approach.” Delft Hydraulics: 335–342.

Suez Canal

Egypt

The Suez Canal, an artificial waterway across the Isthmus of Suez in northeastern Egypt, connects Port Said on the Mediterranean coast with Port Tawfiq on the Gulf of Suez, an inlet of the Red Sea. The 101-mile (163-kilometer) canal has no locks, making it the longest of its kind, sea level being the same at both ends. Because it exploits three natural bodies of water—Lake Manzala in the north; Lake Timsah, almost exactly at the midpoint; and a chain known as the Great Bitter Lake in the south, accounting for about 18 percent of its length—it does not follow the shortest possible route. For most of the canal, traffic is limited to a single lane, but there are passing bays, as well as two-lane bypasses in the Great Bitter Lake. A railway on the west bank runs parallel to the canal from end to end. It took a force of an estimated 1.5 million Egyptian laborers, often working under appalling conditions, eight years to dig the Suez Canal; more than 125,000 lost their lives. In every way, the project is comparable with the architectural and engineering feats of pharaonic Egypt.

In fact, the idea of a navigable link between the Mediterranean and Red Seas dates from dynastic Egypt. Earlier canals joined the Red Sea to the Nile, with obvious economic advantages for the land of the Nile. The first, said to have been commissioned by Ramses I around 2000 b.c., linked the Red Sea and the Nile, and a second component was formed by a branch of the Pelusian River that extended to the Mediterranean. Other sources claim that the first canal was constructed in the reign of Tuthmosis III (1512–1448 b.c.), and still others that Necho II (reigned 610–595 b.c.) initiated it, but lack of maintenance meant that it later became unnavigable. Whatever the case, the Persian king Darius I (558–486 b.c.) ordered the work to be completed. His canal, linking the Gulf of Suez to the Great Bitter Lake and the lake to the Nile Delta, remained in good repair through the Macedonian era. It was redug in the time of the Roman emperor Trajan (a.d. 53–117) and again by the Arab ruler Amr Ibn-Al-Aas. When a trade route around Africa was discovered, it again fell into disuse until about 1800. About then, Napoléon Bonaparte’s engineers proposed a shorter route to India by digging a north-south canal through the Isthmus of Suez. But they wrongly believed that there was a difference in sea level of about 32 feet (10 meters), an error that undermined