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Project overview
The Thames Barrier is one of the world’s largest and most prestigious moveable flood defence structures. It was designed by Rendel who also supervised the construction of one Europe’s largest civil engineering projects undertaken between 1975 and 1985. The Barrier protects London from North Sea surges which, when combined with high astronomic tides and heavy fluvial flows, could result in flooding over large areas to effectively take London out of action for up to six months.
The structure covers the entire width of the River Thames at Woolwich, with four primary openings of 61m to permit navigation and six subsidiary gated openings.
A novel feature is the 19m high, 3,400 tonne Rising Sector Gates (RSG’s) in the navigational openings, which lie in recessed sills in the river bed when not in use to allow unobstructed passage of river traffic through the Barrier. Each gate is pivoted and supported between concrete piers, which contain the operating machinery and control equipment, with primary controls located on the south bank.
All gates are designed to withstand a design surge differential head of 8.4m from the downstream side. When a flood threat is imminent, the gates are swung up through 90 degrees to a vertical position and form a continuous barrier across the river.
Initial Studies (1960’s)
Following the disastrous tidal flooding and loss of life in the Thames Estuary and east coast, studies were under taken to estimate the potential levels and frequency of tidal surges and the impact these could have on the Thames Estuary and London. Various schemes and locations were considered before Rendel recommended a unique form of structure – a Rising Sector Gate – located at Woolwich Reach, with several gates of differing sizes completing the closure of the 520m river width.
Design Phase (1970 – 1974)
In 1970 The Greater London Council, instructed Rendel to proceed with their recommendation and, given the uniqueness of the scheme, the design was accompanied by considerable research and development. The novel concept of the RSG’s had to be tested structurally and hydrodynamically. Rendel directed the testing at Imperial College London, and Manchester and Cambridge Universities. Design criteria were agreed between the Executing Agent and Consultants, based on the earlier studies and required the design to withstand a 1,000-return surge tide, covering the conditions pertaining to the year 2030. A key parameter in the design approach was to ensure unimpeded navigation of the river during construction.
