The Thames Barrier is a movable barrier system that is designed to prevent the floodplain of most of Greater London from being flooded by exceptionally high tides and storm surges moving up from the North Sea. It has been operational since 1982. When needed, it is closed (raised) during high tide; at low tide it can be opened to restore the river’s flow towards the sea. Built approximately 3 km (1.9 mi) due east of the Isle of Dogs, its northern bank is in Silvertown in the London Borough of Newham and its southern bank is in the New Charlton area of the Royal Borough of Greenwich, from where I took this photo.
Design and construction
The report of Sir Hermann Bondi on the North Sea flood of 1953 affecting parts of the Thames Estuary and parts of London was a big factor in the planning of the barrier
The concept of the rotating gates was devised by (Reginald) Charles Draper. In 1969, from his parents’ house in Pellatt Grove, Wood Green, London, he constructed a working model. The novel rotating cylinders were based on the design of the taps on his gas cooker. The barrier was designed by Rendel, Palmer and Tritton for the Greater London Council and tested at the Hydraulics Research Station, Wallingford. The site at New Charlton was chosen because of the relative straightness of the banks, and because the underlying river chalk was strong enough to support the barrier. Work began at the barrier site in 1974 and construction, which had been undertaken by a Costain/Hollandsche Beton Maatschappij/Tarmac Constructionconsortium, was largely complete by 1982. The gates of the barrier were made by Cleveland Bridge UK Ltd at Dent’s Wharf on the River Tees.
In addition to the barrier, the flood defences for 11 miles (18 km) down river were raised and strengthened. The barrier was officially opened on 8 May 1984 by Queen Elizabeth II.The barrier cost £461 million (£1.16 billion now). Total construction cost was around £534 million (£1.6 billion at 2016 prices) with an additional £100 million for river defences
Built across a 520-metre (570 yd) wide stretch of the river, the barrier divides the river into four 61-metre (200 ft) and two approximately 30-metre (100 ft) navigable spans. There are also four smaller non-navigable channels between nine concrete piers and two abutments. The flood gates across the openings are circular segments in cross section, and they operate by rotating, raised to allow “underspill” to allow operators to control upstream levels and a complete 180 degree rotation for maintenance. All the gates are hollow and made of steel up to 40 millimetres (1.6 in) thick. The gates are filled with water when submerged and empty as they emerge from the river. The four large central gates are 20.1 metres (66 ft) high and weigh 3,700 tonnes each. Four radial gates by the river banks, also about 30 metres (100 ft) wide, can be lowered. These gate openings, unlike the main six, are non-navigable.