The barrier was completed in 1982, the contract value was £92 million, this was carried out on behalf of Greater London Council, Department of Public Health Engineering. The barrier was built to prevent surge flooding in London, it spans 520 metres (a third of a mile) across the Thames and it is the world's largest movable flood barrier.
The barrier comprises of four 61 metre and two 31 metre rising sectors and four 31 metre falling radial gates with operating machinery. Cleveland Bridge were responsible for the supply and erection of 9,600 tonnes of fabricated steel gates and the installation of the mechanical and hydraulic operating machinery.
 The Thames Barrier |
The Barrier was designed by Rendel, Palmer & Tritton (now known as High Point Rendel). It was initially guaranteed to prevent the capital from flooding until the year 2030, these figures were derived from the estimated rise in sea levels. Since 1982 the barrier has been raised more than 25 times, mainly as a precautionary measure. However, it is possible to raise the gates an extra metre, by turning them approximately 20 degrees, this would also mean that the down river flood walls would have to be raised. Half a million tonnes of concrete were used to build the piers and the sills on which the gates rest on the river bed when being used. When raised each of the 4 main gates is as high as a 5 storey building and as wide as the opening of Tower Bridge (61 metres). The gates are moved by electrically powered hydraulic power packs. |