Thames Barrier

Thames Barrier
Thames Barrier
	View of the barrier gates, which are closed when a high tide is forecast
Country	United Kingdom
Location	London
Coordinates	51°29′49″N 0°2′12″E / 51.49694°N 0.03667°E
Purpose	Flood control
Status	Operational
Construction began	1974
Opening date	8 May 1984
Construction cost	£534 million
Built by	Costain; Hollandsche Beton Maatschappij; Tarmac Construction; Tysons, Liverpool; Cleveland Bridge & Engineering;
Operator(s)	Environment Agency
Dam and spillways
Type of dam	Barrage
Impounds	River Thames
Height (thalweg)	20.1 metres
Length	520 metres
Turbines	0
	Website; GOV.UK page

The Thames Barrier is a retractable barrier system built to protect the floodplain of most of Greater London from 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 about 2 miles (3.2 kilometres) 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.