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The Thames Barrier is the world's second largest movable flood barrier. It is a flood control structure located downstream of central London. The barrier's purpose is to prevent London from being flooded by an exceptionally high tide moving up from the sea, often exacerbated by a storm surge. It only needs to be raised for the duration of the high tide; at ebb tide it can be lowered to release upstream water that backs up behind it. On the northern bank it lies in the area of Silvertown in the London Borough of Newham. On the southern bank it lies in the New Charlton area of Charlton in the London Borough of Greenwich.
Historical needs for a barrier
London is quite vulnerable to flooding. A storm surge generated by low pressure in the Atlantic Ocean sometimes tracks eastwards past the north of Scotland and may then be driven into the shallow waters of the North Sea. The storm surge is funnelled down the North Sea which narrows towards the English Channel and the Thames Estuary. If the storm surge coincides with a spring tide then dangerously high water levels can occur in the Thames Estuary. This situation combined with downstream flows in the Thames provides the triggers for flood defence operations.
The threat has increased over time due to the slow but continuous rise in high water level over the centuries (20 cm / 100 years) and the slow "tilting" of Britain (up in the north and west, and down in the south and east) caused by post-glacial rebound.
Fourteen people died in the 1928 Thames flood, and after 307 people died in the UK in the North Sea Flood of 1953 the issue gained new prominence.
Early proposals for a flood control system were stymied by the need for a large opening in the barrier to allow for vessels from London Docks to pass through. When containerization came in and a new port was opened at Tilbury, a smaller barrier became feasible with each of the four main navigation spans being the same width as the opening of Tower Bridge.
Design and construction
One of the gates in underspill (March 2007)
The concept of the rotating gates was devised by Charles Draper. The barrier was designed by Rendel, Palmer and Tritton for the Greater London Council and tested at HR Wallingford Ltd. The site at Woolwich 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 Construction consortium,[1] was largely complete by 1982. In addition to the barrier itself the flood defences for 11 miles down river were raised and strengthened. The barrier was officially opened on 8 May 1984 by Her Majesty Queen Elizabeth II. Total construction cost was around £534 m (£1.3 billion at 2001 prices) with an additional £100 m 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 about 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 40mm thick. The gates fill 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 3,500 tonnes. [2] Four radial gates by the riverbanks, also about 30 metres (100 ft) wide, can be lowered. These gate openings, unlike the main six, are non-navigable.
Prediction for operation
A Thames Barrier flood defence closure is triggered when a combination of high tides forecast in the North Sea and high river flows at the tidal limit at Teddington weir indicate that water levels would exceed 4.87 m in central London. Forecast sea levels at the mouth of the Thames Estuary are generated by Met Office computers and also by models run on the Thames Barrier's own forecasting and telemetry computer systems. About 9 hours before the high tide reaches the barrier a flood defence closure begins with messages to stop river traffic, close subsidiary gates and alert other river users. As well as the Thames Barrier, the smaller gates along the Thames Tideway include Barking Barrier, King George V Lock gate, Dartford Barrier and gates at Tilbury Docks and Canvey Island. Once river navigation has been stopped and all subsidiary gates closed, then the Thames Barrier itself can be closed. The smaller gates are closed first, then the main navigable spans in succession. The gates remain closed until the tide downstream of the barrier falls to the same level as the water level upstream.
After periods of heavy rain west of London, floodwater can also flow down the Thames upstream from London. Because the river is tidal from Teddington weir all the way through London, this is only a problem at high tide, which prevents the floodwater from escaping out to sea. From Teddington the river is opening out into its estuary, and at low tide it can take much greater flow rates the further one goes downstream. In periods when the river is in flood upstream, if the gates are closed shortly after low tide, a huge empty volume is created behind the barrier which can act as a reservoir to hold the floodwater coming over Teddington weir. Most river floods will not fill this volume in the few hours of the high tide cycle during which the barrier needs to be closed. If the barrier was not there, the high tide would fill up this volume instead, and the floodwater could then spill over the river banks in London.
Barrier closures and incidents
Before 1990, the number of barrier closures was one to two per year on average. Since 1990, the number of barrier closures has increased to an average of about four per year. In 2003 the Barrier was closed on 14 consecutive tides.
An incident which had the potential to be catastrophic for London occurred on 27 October 1997. The dredger, MV Sand Kite, sailing in thick fog, collided with one of the Thames Barrier's piers. As the ship started to sink she dumped her 3,300 tonne load of aggregate, finally sinking by the bow on top of one of the barrier's gates where she lay for several days. Initially the gate could not be closed as it was covered in a thick layer of gravel. A longer term problem was the premature loss of paint on the flat side of the gate caused by abrasion. One estimate of the cost of flooding damage, had it occurred, was around £13 billion.[3] The vessel was refloated in mid-November 1997.
The barrier was closed twice on 9 November 2007 after a storm surge in the North Sea which was compared to the one in 1953.[4] The main danger of flooding from the surge was on the coast above the Thames Barrier, where evacuations took place, but the winds abated a little and, at the Thames Barrier, the 9 November 2007 storm surge did not completely coincide with high tide.
Ownership / operating authority
The barrier was originally commissioned by the Greater London Council under the guidance of Ray Horner. After the 1986 abolition of the GLC it was operated successively by Thames Water Authority and then the National Rivers Authority until April 1996 when it passed to the Environment Agency.
Future
The barrier was originally designed to protect London against a flood level with a return period of 1000 years in the year 2030 after which the protection would decrease but be within acceptable limits [6]. This defence level included long term changes in sea and land levels as understood at that time (c. 1970). Since then sea level rise due to global warming has been identified. Based on current estimates[7] the barrier will be able to cope with projected sea level rises until around 2060–2070 and is expected to serve its full term. Since 1982 (up to 2007) the barrier has been raised over 100[8] times; further, it is raised every month for testing.
In 2005, a suggestion was made public that it might become necessary to supersede the Thames Barrier with a much more ambitious 16 km (10 mi) long barrier across the Thames Estuary from Sheerness in Kent to Southend in Essex.
Wikipedia
Barrier - A rusted and weathered grill, part of the ventilation system of a seasonal greenhouse at The Farm at South Mountain, Phoenix, Arizona. 8 year old image shot with Canon 40D and 100mm f/2.8 lens.
Hasselblad 500 C/M
Carl Zeiss Distagon 50mm f/4 C T*
Fuji Reala 100
Tetenal Colortec C-41
Scan from negative film
Found an expired roll of Kodak Gold 400, and took it out with the Xpan using a 35mm PC Nikkor and zone focusing. I think this is the lens I like the most on the Xpan - wide but not too wide; nice color; keeps me in the moment.
Stone, grass, concrete & gravel
All we got to keep us together
Stone, grass, concrete & gravel
Maybe one day things will get better
Jamie T (amended)
Listen here
Appropriately enough taken at...Barrier Park, East London, UK
The Thames Barrier Park is a 22 acres (8.9 ha) park in London's docklands, named after its location on the north side of the River Thames next to the Thames Barrier. It is intended to aid the regeneration of the area by creating an attractive public space alongside residential and commercial developments. It is adjacent to Pontoon Dock DLR station in the Silvertown area of the London Borough of Newham.
We can customize any bathroom to prepare your home for age-in-place living. This project allowed a woman to move back home from a nursing home. A exterior elevator lift was added to assist her getting in and out of the home.
The Thames Barrier is located downstream of central London. Operational since 1982, its purpose is to prevent the floodplain of all but the easternmost boroughs of Greater London from being flooded by exceptionally high tides and storm surges moving up from the North Sea
Town Hall Station
Sydney, NSW, Australia
From the "Subterraneities" Series
Image taken with a WIdelux F6B .—Camera hand-held with custom hand-grip and cable release.—Shot on AgfaVista 200 stock. The film was commercially developed in a lab in Albury (NSW) and later scanned with an Epson Perfection V700, using Silverfast Negafix software.
© Dirk HR Spennemann 2011, All Rights Reserved
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Colas Class 47/7 47739 "Robin of Templecombe" catches the last of the light as it heads past Grazeley between Basingstoke and Reading with an Eastleigh to Doncaster Barrier Wagon move ready to bring a Class 458/5 EMU to Wimbledon overnight.
Remains of a military barrier north of Rothenbrunnen, between railway and Hinterrhein. On the road and the railroad embankment left top in the picture, there was formerly a prepared explosive device from the cold war. Because of the overgrowth, the place was not accessible from below. Switzerland, July 7, 2018.
The fog seemingly stopped as soon as it reached the Golden Gate leaving the rest of San Francisco free from the fog.
Porterbrook/DB barrier vehicles 6376, 6377 and 6378 at Toton
6376 / 975973 ex ADB975973
6377 ex ADB975975
6378 ex ADB975971
60033 "Tees Steel Express" and 60061 "Alexander Graham Bell" in the background with others.
60061 was withdrawn from traffic 31/10/2013 WQCA - DBS Locomotives Stored for Component Recovery Group 3 - Headquarters (WQ) and 033 the same day 31/10/2013 WQCA - DBS Locomotives Stored for Component Recovery Group 3 - Headquarters (WQ).
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.
History
Background
Flooding in London has been a problem since the city was first established in Roman times.[1] In 1954 the Waverley Committee, established to investigate the serious North Sea flood of 1953 which affected parts of the Thames Estuary and parts of London, recommended that "as an alternative to raising the banks, the possibility and cost of erecting a structure across the Thames which could be closed in a surge should be urgently investigated".[2] A large number of designs were put forward, ranging from a huge road viaduct with two 500 foot (150 m) sluice gates crossing the Thames at Crayfordness to flap gates lying on the river bed and floated up by compressed air.[3] By 1965, when the Greater London Council (GLC) took over responsibility, two major schemes were under consideration, costed at £24 million and £41 million respectively[3] (£500 million and £800 million at 2020 prices).
In 1966 Sir Hermann Bondi was asked to take an independent view of the situation. He considered the estimated construction costs and the probability of a flood and of damage if the barrier was not built. He strongly recommended that a barrier should be built in order to avoid the catastrophe of flooding central London, and a site was agreed at Woolwich.
The barrier protects central London against a storm surge, caused when a deep depression forms to the north of Scotland and progresses across the North Sea and south-easterly towards southern Scandinavia. When such a surge coincides with a high spring tide, the high winds associated with the depression can funnel the water up the Thames Estuary and cause surges of up to 3.5 metres. The planners assessed that in the absence of a barrier, such a surge could inundate 45 square miles (117 km2) of land, put hospitals, powers stations and the London Underground out of action and cause damage estimated in 1966 at £2.0 billion[4] (about £50 billion at 2020 prices). The barrier was designed to provide a flood defence capable of resisting a once in 1000 year surge tide at a base date of 2030.
Design and construction
Diagram showing how the gates work, though the barrier actually rises further than this to allow water to "underspill" under the barrier in a controlled fashion
The concept of the rising sector 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 the concept 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.
The Thames Barrier and Flood Prevention Act, authorising construction, was passed in 1972. In 1974 the GLC placed the two major construction contracts. Civil construction was undertaken by a Costain/Hollandsche Beton Maatschappij/Tarmac Construction consortium. A separate contract for the gates and operating machinery was placed with the Davy Cleveland Barrier Consortium[3], formed by Davy McKee Ltd of Sheffield and Cleveland Bridge UK Ltd..
Work began at the barrier site in 1974 and progressed in two phases. The southern piers (9 to 6) were built first, with river traffic diverted to the north side, then traffic routed through the completed southern spans whilst the north side piers (1 to 5) were built. During construction of the piers, precast concrete sills were built in a cofferdam on the north side of the river and floated out and sunk between the piers to form the gate recesses, with access tunnels at the upstream and downstream ends.
The gates of the barrier were fabricated in sections at Cleveland Bridge's Darlington works and assembled at Port Clarence on the River Tees. The gates, gate arms and rocking beams were transported from the Tees to the Thames by barge and lifted into position by two very large floating cranes operated by Neptun of Hamburg (now part of SMIT). The mechanical and hydraulic machinery was built by Davy Loewy, Henry Berry and Vickers and trial assembled in Davy's Darnall works. Delays to the civil works required changes to the construction and installation sequence, but commissioning was relatively uneventful and the first trial operation of all the gates together was carried out on 31 October 1982.
In addition to the barrier, the flood defences 18 kilometres (11 mi) 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 (1,710 ft) 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.[13] 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.
Predictions for operation
A Thames Barrier flood defence closure is triggered when a combination of high tides forecast in the North Sea and high river flows at the tidal limit at Teddington weir indicate that water levels would exceed 4.87 metres (16.0 ft) in central London. Though Teddington marks the Normal Tidal Limit, in periods of very high fluvial flow the tidal influence can be seen as far upstream as East Molesey on the Thames.
During the barrier's entire history up to June 2020, there have been 193 flood defence closures[16]. The barrier was closed twice on 9 November 2007 after a storm surge in the North Sea which was compared to the one in 1953.[17] The main danger of flooding from the surge was on the coast above the Thames Barrier, where evacuations took place, but the winds abated a little and, at the Thames Barrier, the 9 November 2007 storm surge did not completely coincide with high tide.
On 20 August 1989, hours after the Marchioness disaster, the barrier was closed against a spring tide for 16 hours "to assist the diving and salvage operations".
The barrier has survived 15 boat collisions without serious damage.
On 27 October 1997, the barrier was damaged when the dredger MV Sand Kite, operating in thick fog, hit one of the Thames Barrier's piers. As the ship started to sink she dumped her 3,300-tonne load of aggregate, finally sinking by the bow on top of one of the barrier's gates, where she lay for several days. Initially the gate could not be closed as it was covered in a thick layer of gravel. A longer-term problem was the premature loss of paint on the flat side of the gate caused by abrasion. The vessel was refloated in mid-November 1997.
The annual full test closure in 2012 was scheduled for 3 June to coincide with the Thames pageant celebrating Queen Elizabeth II's Diamond Jubilee. Flood risk manager Andy Batchelor said the pageant gave the Environment Agency "a unique opportunity to test its design for a longer period than we would normally be able to", and that the more stable tidal conditions in central London that resulted would help the vessels taking part.
Ownership and operating authority
The barrier was originally commissioned by the Greater London Council under the guidance of Ray Horner. After the 1986 abolition of the GLC it was operated successively by Thames Water Authority and then the National Rivers Authority until April 1996 when it passed to the Environment Agency.
Future
The barrier was originally designed to protect London against a very high flood level (with an estimated return period of one hundred years) up to the year 2030, after which the protection would decrease, while remaining within acceptable limits.[23] At the time of its construction, the barrier was expected to be used 2–3 times per year. By the mid-2000s it was being operated 6–7 times a year.[24] In the 2010s, the barrier was generally closed twice a year but the average is still 6-7 due to the barrier being raised 50 times in 2013–14.
This defence level allowed for long-term changes in sea and land levels as understood at that time (c. 1970). Despite global warming and a consequently greater predicted rate of sea level rise, recent analysis extended the working life of the barrier until around 2060–2070.[citation needed] From 1982 until 19 March 2007, the barrier was raised one hundred times to prevent flooding. It is also raised monthly for testing, with a full test closure over high tide once a year.
Released in 2005, a study by four academics contained a proposal to supersede the Thames Barrier with a more ambitious 16 km (10 mi) long barrier across the Thames Estuary from Sheerness in Kent to Southend in Essex.
In November 2011, a new Thames Barrier, further downstream at Lower Hope between East Tilbury in Essex and Cliffe in Kent, was proposed as part of the Thames Hub integrated infrastructure vision. The barrier would incorporate hydropower turbines to generate renewable energy and include road and rail tunnels, providing connections from Essex to a major new hub airport on the Isle of Grain.
In January 2013, in a letter to The Times, a former member of the Thames Barrier Project Management Team, Dr Richard Bloore, stated that the flood barrier was not designed with increased storminess and sea level rises in mind, and called for a new barrier to be looked into immediately. The Environment Agency responded that it does not plan to replace the Thames Barrier before 2070, as the barrier was designed with an allowance for sea level rise of 8 mm (0.31 in) per year until 2030, which has not been realised in the intervening years. The barrier is around halfway through its designed lifespan. The standard of protection it provides will gradually decline over time after 2030, from a 1-in-1000-year event. The Environment Agency are examining the Thames Barrier for its potential design life under climate change, with early indications being that subject to appropriate modification, the Thames Barrier will be capable of providing continued protection to London against rising sea levels until at least 2070.
In June 2019 architects Lifschutz Davidson Sandilands and marine engineers Beckett Rankine launched a proposal for a pedestrian and cycle bridge located next to the Thames Barrier; the scheme, called the Thames Barrier Bridge, was promoted as the only location in east London where a low-level opening bridge across the Thames could have relatively moderate opening spans of about 60 m (200 ft).