Thames Flood Barrier, Woolwich, Greater London
The Thames Barrier is one of the largest movable flood barriers in the world. The barrier spans 520 metres across the River Thames near Woolwich. Its northern bank is in Silvertown in the London Borough of Newham (top of photograph). Its southern bank is in the New Charlton area of Charlton in the London Borough of Greenwich. It protects 125 square kilometres of central London from flooding caused by tidal surges. It has 10 steel gates that can be raised into position across the River Thames. When raised, the main gates stand as high as a five-storey building and as wide as the opening of Tower Bridge. Each main gate weighs 3,300 tonnes. In the 1980s there were four closures, 35 closures in the 1990s and 75 closures in the first decade of this century.