Extreme Engineering

Venice Flood Gates (2x2)

: 14, 2004

Venice floodgates Fact file When built: Started 2003, completion due 2010 Height: 30m Weight: 300 tons each Timescale: Seven years Construction material: Steel Number of barriers: 79 Capacity: Stop tides of up to 2m In 1900, St. Mark's Square in Venice flooded about 10 times a year. Now water covers it 100 times a year. Global warming is causing sea levels around the world to rise and environmental experts believe Venice may well go the same way as Atlantis. In September 2003, work began to prevent the city’s 45km of canals from cannibalising its ancient architecture. Phase one saw dredging machines begin to remove 3.8 million cubic metres of clay from the lagoon bed at the mouth of its three inlets. This is being replaced with 9m tons of rock and concrete to provide a sturdy foundation to fix the 79 steel floodgates. Each is bigger than a football field and weighs over 300 tons. When not in use, the gates will lie flat against the lagoon floor. At the threat of a high tide, hydraulic valves can be opened at the flick of a switch allowing the gates to pivot into position. At a cost of $3 billion, the project isn’t exactly cheap. But then, it’s less than the estimated losses during Venice’s worst ever flood in 1966.