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84-665: Three Mills Lock , also known as Prescott Lock , is a lock on the Prescott Channel on the River Lea in London . The current structure was constructed by British Waterways and officially opened on 5 June 2009. The lock cuts off a section of the Bow Back Rivers from the tide, creating new opportunities for leisure boats, water taxis, trip boats and floating restaurants . It also allowed barges carrying construction materials to access

168-473: A Provisional IRA bomb on a Metropolitan line train. The terrorist then shot and killed the train's driver Julius Stephen. The station is located at the corner of Durban Road and Manor Road, in the London Borough of Newham . The station is named after the former parish and borough of West Ham within which it was located to the west of the centre. The neighbourhood of West Ham is located some distance to

252-419: A fish ladder are often taken to counteract this. Navigation locks have also potential to be operated as fishways to provide increased access for a range of biota. Locks can be built side by side on the same waterway. This is variously called doubling , pairing , or twinning . The Panama Canal has three sets of double locks. Doubling gives advantages in speed, avoiding hold-ups at busy times and increasing

336-555: A boat in a lock. One incident, which took place in June 1873 on the Chesapeake and Ohio Canal, involved the boat the Henry C. Flagg and its drunk captain. That boat was already leaking; the crew, having partially pumped the water out, entered Lock 74, moving in front of another boat. Because they failed to snub the boat, it crashed into and knocked out the downstream gates. The outrush of water from

420-464: A boat in the lock. A 200-ton boat moving at a few miles an hour could destroy the lock gate. To prevent this, a rope was wound around the snubbing post as the boat entered the lock. Pulling on the rope slowed the boat, due to the friction of the rope against the post. A rope 2 + 1 ⁄ 2 inches (6.4 cm) in diameter and about 60 feet (18 meters) long was typically used on the Erie Canal to snub

504-500: A boat travelling upstream, the process is reversed; the boat enters the empty lock, and then the chamber is filled by opening a valve that allows water to enter the chamber from the upper level. The whole operation will usually take between 10 and 20 minutes, depending on the size of the lock and whether the water in the lock was originally set at the boat's level. Boaters approaching a lock are usually pleased to meet another boat coming towards them, because this boat will have just exited

588-528: A broad canal for more than one boat to be in a staircase at the same time, but managing this without waste of water requires expertise. On English canals, a staircase of more than two chambers is usually staffed: the lockkeepers at Bingley (looking after both the "5-rise" and the "3-rise") ensure that there are no untoward events and that boats are moved through as speedily and efficiently as possible. Such expertise permits miracles of boat balletics: boats travelling in opposite directions can pass each other halfway up

672-554: A chamber with gates at both ends that control the level of water in the pound. In contrast, an earlier design with a single gate was known as a flash lock . Pound locks were first used in China during the Song dynasty (960–1279 CE), having been pioneered by the Song politician and naval engineer Qiao Weiyue in 984. They replaced earlier double slipways that had caused trouble and are mentioned by

756-426: A flight of locks is simply a series of locks in close-enough proximity to be identified as a single group. For many reasons, a flight of locks is preferable to the same number of locks spread more widely: crews are put ashore and picked up once, rather than multiple times; transition involves a concentrated burst of effort, rather than a continually interrupted journey; a lock keeper may be stationed to help crews through

840-412: A gate, or pair of half-gates, traditionally made of oak or elm but now usually made of steel ). The most common arrangement, usually called miter gates , was invented by Leonardo da Vinci sometime around the late 15th century. On the old Erie Canal , there was a danger of injury when operating the paddles: water, on reaching a certain position, would push the paddles with a force which could tear

924-421: A lock. To help boats traveling downstream exit a lock, the locksman would sometimes open the paddles to create a swell, which would help "flush" the boat out of the lock. A boatsman might ask for a back swell, that is, to open and shut the paddles a few times to create some waves, to help him get off the bank where he was stuck. If boats ran aground (from being overloaded) they sometimes asked passing crews to tell

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1008-545: A main road, to connect the Jubilee line and North London line platforms with the new ticket hall and the rest of the station. Jubilee line services began on 14 May 1999. North London Line services at the station ceased on 9 December 2006, when the line from Stratford to North Woolwich was closed, to allow for the line to be converted for the Docklands Light Railway . The platforms reopened on 31 August 2011 as part of

1092-698: A new wharf on the Waterworks River . Barges can pass directly into the northern section of Bow Creek to the River Thames . The head of water created by the lock may be used to fill the mill pound and once more allow operation of the Three Mills tidal mill. The lock officially opened on Friday 5 June 2009, but the expected use of the lock for the construction of the Olympic Park was reportedly much lower than originally planned. West Ham and Bromley-by-Bow are

1176-430: A short way into the chamber from below the upper gates. Allowing the rear of the boat to "hang" on the cill is the main danger when descending a lock, and the position of the forward edge of the cill is usually marked on the lock side by a white line. The edge of the cill is usually curved, protruding less in the center than at the edges. In some locks, there is a piece of oak about 9 in (23 cm) thick which protects

1260-480: A staircase lock can be used as an emergency dry dock). To avoid these mishaps, it is usual to have the whole staircase empty before starting to descend, or full before starting to ascend, apart from the initial chamber. One striking difference in using a staircase of either type (compared with a single lock, or a flight) is the best sequence for letting boats through. In a single lock (or a flight with room for boats to pass) boats should ideally alternate in direction. In

1344-404: A staircase, however, it is quicker for a boat to follow a previous one going in the same direction. Partly for this reason staircase locks such as Grindley Brook, Foxton, Watford and Bratch are supervised by lockkeepers, at least during the main cruising season, they normally try to alternate as many boats up, followed by down as there are chambers in the flight. As with a flight, it is possible on

1428-454: A swell to anyone to help them on the way, but some would ask for money for the swell. The Erie Canal management did not like swelling for two reasons. First, it used too much water lowering the water on the pound above sometimes causing boats to run aground. In addition, it raised the water level on the pound below, causing some boats to strike bridges or get stuck. On horse-drawn and mule-drawn canals, snubbing posts were used to slow or stop

1512-426: Is a normal top gate, and the intermediate gates are all as tall as the bottom gate). As there is no intermediate pound, a chamber can only be filled by emptying the one above, or emptied by filling the one below: thus the whole staircase has to be full of water (except for the bottom chamber) before a boat starts to ascend, or empty (except for the top chamber) before a boat starts to descend. In an "apparent" staircase

1596-457: Is able to hold two 350-tonne barges (the present locks on the nearby Lee Navigation limit barges to about 120 tonnes). The tidal range is handled by the use of hydraulic sector gates at both ends of the lock, and the structure incorporates two large rising radial gates for flood control in the Bow Back Rivers. A site in the river just south of this lock is the resting place of the remains of

1680-443: Is only a staircase if successive lock chambers share a gate (i.e. do not have separate top and bottom gates with a pound between them). Most flights are not staircases, because each chamber is a separate lock (with its own upper and lower gates), there is a navigable pound (however short) between each pair of locks, and the locks are operated in the conventional way. However, some flights include (or consist entirely of) staircases. On

1764-846: The Bollène lock on the River Rhône has a fall of at least 23 m (75 ft), the Leerstetten, Eckersmühlen and Hilpoltstein locks on the Rhine–Main–Danube Canal have a fall of 24.67 m (80.9 ft), each and the Oskemen Lock on the Irtysh River in Kazakhstan has a drop of 42 m (138 ft). The natural extension of the flash lock , or staunch, was to provide an upper gate (or pair of gates) to form an intermediate "pound" which

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1848-464: The Caledonian Canal the lock gates were operated by man-powered capstans , one connected by chains to open the gate and another to draw it closed. By 1968 these had been replaced by hydraulic power acting through steel rams. The construction of locks (or weirs and dams) on rivers obstructs the passage of fish. Some fish such as lampreys, trout and salmon go upstream to spawn. Measures such as

1932-591: The District line . Hammersmith & City line services started, as part of the Metropolitan line, in 1936. The southern platforms were removed after war damage in 1940 which had completely closed the station from 7 September 1940 until 11 August 1941. After nationalisation of the railways in 1948 management of the station passed to British Railways . In 1969 ownership was transferred to the London Underground and

2016-588: The Euston Arch . A footbridge for pedestrians and a fish pass for migrating fish was incorporated into the design of the lock, and British Waterways planned associated improvements to the navigation and tow path, as a part of the Olympic legacy. An unexploded 2,200-pound (998 kg) Hermann bomb from World War II was found on 2 June 2008. The bomb was made safe, in a controlled explosion, after five days of disruption to tube and rail services. The effect of building

2100-470: The Grand Union . Operation of a staircase is more involved than a flight. Inexperienced boaters may find operating staircase locks difficult. The key worries (apart from simply being paralysed with indecision) are either sending down more water than the lower chambers can cope with (flooding the towpath, or sending a wave along the canal) or completely emptying an intermediate chamber (although this shows that

2184-648: The Kennet and Avon Canal . West Ham tube station West Ham is a London Underground , Docklands Light Railway (DLR) and National Rail intermodal interchange station in West Ham , London , United Kingdom . The station is served by London Underground 's District , Hammersmith & City and Jubilee lines , the Stratford International branch of the DLR , and c2c National Rail services. The station

2268-573: The Memorial Grounds , secured an agreement with the London, Tilbury and Southend Railway to build a station at the intersection of Manor Road and Memorial Avenue. The company board approved this in February 1898 and Mowlem 's was given the contract to build a four platform station, which allowed for the proposed quadrupling of the line with the completion of the Whitechapel and Bow Railway . The station

2352-551: The Metropolitan District Railway to operate through West Ham to Upminster from 1902. The Metropolitan District converted to electric trains in 1905 and services were cut back to East Ham. The London, Tilbury and Southend Railway trains from Fenchurch Street used the southern platforms when the Metropolitan District services began but stopping was reduced to a few a week in 1908 and to nil in 1913. Ownership of

2436-670: The Olympic Park in Stratford. Work began in January 2011, with the construction of temporary stairs and a walkway from the eastern end of the District line platforms, over the eastbound track and running back parallel to the platform ending at Manor Road. The footbridge was demolished in mid-October 2012, following the end of the 2012 Summer Paralympics . The foundations of the temporary footbridge have been left for possible use in future expansion of

2520-700: The Rochdale Canal , which both have a rise of nearly 20 feet (6.1 m). Both locks are amalgamations of two separate locks, which were combined when the canals were restored to accommodate changes in road crossings. By comparison, the Carrapatelo and Valeira locks on the Douro river in Portugal, which are 279 feet (85 m) long and 39 feet (12 m) wide, have maximum lifts of 115 and 108 feet (35 and 33 m) respectively. The two Ardnacrusha locks near Limerick on

2604-581: The Song dynasty (960–1279 CE). The Songshi or History of the Song Dynasty, volume 307, biography 66, records how Qiao Weiyue, a high-ranking tax administrator, was frustrated at the frequent losses incurred when his grain barges were wrecked on the West River near Huai'an in Jiangsu . The soldiers at one double slipway, he discovered, had plotted with bandits to wreck heavy imperial barges so that they could steal

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2688-454: The main line from Fenchurch Street, now operated by c2c . As part of the work, the existing entrance was closed, and the refurbished ticket hall became a connecting concourse to the new ticket hall and the rest of the station. Additionally, the station was made fully accessible. The island platform for c2c services, along with the access staircases, are narrow and get easily congested. To ensure safety for passengers, staff must be present on

2772-523: The (new) c2c platforms. A new ticket hall - facing onto Manor Road - connects this concourse to the Jubilee line and North London line platforms via a high level bridge that spans four rail lines and a main road. The station building and connecting passageways are finished in a mixture of red brick, concrete and glass, inspired by Charles Holden. The station was built at a fraction of the cost of other Jubilee Line Extension stations, just £10.5m compared to over £100m at stations like Canary Wharf . At

2856-548: The 1980s, by which point the Bow Back Rivers had been classified as "remainder waterways" by the Transport Act 1968 , and there was no funding for maintenance. As a consequence of this, the rivers upstream reverted to being tidal. This made navigation difficult, since there was not enough water at low tide, and at high tide, there was insufficient headroom, due to the low level of the Northern Outfall Sewer , which crosses

2940-510: The Chinese polymath Shen Kuo (1031–1095) in his book Dream Pool Essays (published in 1088), and fully described in the Chinese historical text Song Shi (compiled in 1345): The distance between the two locks was rather more than 50 paces, and the whole space was covered with a great roof like a shed. The gates were 'hanging gates'; when they were closed the water accumulated like a tide until

3024-552: The Grand Union (Leicester) Canal, the Watford flight consists of a four-chamber staircase and three separate locks; and the Foxton flight consists entirely of two adjacent 5-chamber staircases. Where a very steep gradient has to be climbed, a lock staircase is used. There are two types of staircase, "real" and "apparent". A "real" staircase can be thought of as a "compressed" flight, where

3108-512: The Shannon navigation in Ireland have a rise of 100 feet (30 m). The upper chamber rises 60 feet (18 m) and is connected to the lower chamber by a tunnel, which when descending does not become visible until the chamber is nearly empty. A pound is the level stretch of water between two locks (also known as a reach ). The cill , also spelled sill , is a narrow horizontal ledge protruding

3192-531: The Three Mills tidal mill. Prior to the development, tidal levels on the Bow Back Rivers reached 15.8 feet (4.8 m) above ordnance datum (AOD) on spring tides. The sluice is designed to stabilise levels at 7.5 feet (2.3 m) AOD, so the lock structure has to cope with levels on the downstream side which might be higher or lower than those on the upstream side. The new lock is 203 feet (62 m) long, 26 feet (8 m) wide and 7.9 feet (2.4 m) deep, and

3276-470: The advent of canals in Britain. The sides of the turf-lock are sloping so, when full, the lock is quite wide. Consequently, this type of lock needs more water to operate than vertical-sided brick- or stone-walled locks. On British canals and waterways most turf-sided locks have been subsequently rebuilt in brick or stone, and so only a few good examples survive, such as at Garston Lock , and Monkey Marsh Lock , on

3360-463: The bottom cill at all but the higher tides – the new bottom chamber rises just far enough to get the boat over the original lock cill. In China, the recently completed Three Gorges Dam includes a double five-step staircase for large ships, and a ship lift for vessels of less than 3000 metric tons. Examples of "apparent" staircases are Foxton Locks and Watford Locks on the Leicester Branch of

3444-617: The canal would cause frequent interruptions of the heavy road traffic. It can be emptied by pumping – but as this uses a lot of electricity the method used when water supplies are adequate is to drain the lock to a nearby burn . In 2016 the Kieldrecht Lock in the Port of Antwerp in Belgium took over the title of the world's largest lock from the Berendrecht Lock in the same port and still has

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3528-588: The chambers so that some water from the emptying chamber helps to fill the other. This facility has long been withdrawn on the English canals, although the disused paddle gear can sometimes be seen, as at Hillmorton on the Oxford Canal . Elsewhere they are still in use; a pair of twinned locks was opened in 2014 on the Dortmund–Ems Canal near Münster , Germany. The once-famous staircase at Lockport, New York ,

3612-617: The chambers still have common gates, but the water does not pass directly from one chamber to the next, going instead via side ponds. This means it is not necessary to ensure that the flight is full or empty before starting. Examples of famous "real" staircases in England are Bingley and Grindley Brook . Two-rise staircases are more common: Snakeholme Lock and Struncheon Hill Lock on the Driffield Navigation were converted to staircase locks after low water levels hindered navigation over

3696-404: The chance of a boat finding a lock set in its favour. There can also be water savings: the locks may be of different sizes, so that a small boat does not need to empty a large lock; or each lock may be able to act as a side pond (water-saving basin) for the other. In this latter case, the word used is usually "twinned": here indicating the possibility of saving water by synchronising the operation of

3780-514: The concept has been suggested in a number of cases, the only example in the world of a drop lock that has actually been constructed is at Dalmuir on the Forth and Clyde Canal in Scotland. This lock, of the single-chamber type, was incorporated during the restoration of the canal, to allow the replacement of a swing bridge (on a busy A road) by a fixed bridge, and so answer criticisms that the restoration of

3864-534: The extension to Stratford International . As part of the TwelveTrees development on the former Parcelforce distribution depot, a new station entrance is being built to connect to the upper Jubilee line concourse. As well as this, two new pedestrian bridges over the railway will be built. The station was rebuilt as part of the Jubilee Line Extension in the 1990s. The majority of the station design

3948-448: The first to solve the problem of keeping the Nile free of salt water when his engineers invented the lock around 274/273 BC. All pound locks have three elements: The principle of operating a lock is simple. For instance, if a boat travelling downstream finds the lock already full of water: If the lock were empty, the boat would have had to wait 5 to 10 minutes while the lock was filled. For

4032-599: The first true pound lock was built in 1396 at Damme near Bruges , Belgium. The Italian Bertola da Novate (c. 1410–1475) constructed 18 pound locks on the Naviglio di Bereguardo (part of the Milan canal system sponsored by Francesco Sforza ) between 1452 and 1458. In Ancient Egypt, the river-locks was probably part of the Canal of the Pharaohs : Ptolemy II is credited by some for being

4116-425: The flight quickly; and where water is in short supply, a single pump can recycle water to the top of the whole flight. The need for a flight may be determined purely by the lie of the land, but it is possible to group locks purposely into flights by using cuttings or embankments to "postpone" the height change. Examples: Caen Hill locks, Devizes . "Flight" is not synonymous with "Staircase" (see below). A set of locks

4200-512: The form of the now-disused Écluse des Lorraines , connecting the Canal latéral à la Loire with the River Allier . A drop lock can consist of two conventional lock chambers leading to a sump pound, or a single long chamber incorporating the sump – although the term properly applies only to the second case. As the pounds at either end of the structure are at the same height, the lock can only be emptied either by allowing water to run to waste from

4284-516: The inside walls of the lock with wood, so as not to abrade the boats. This was done, for instance, on the Chesapeake and Ohio Canal with the locks near the Paw Paw Tunnel . and also the Chenango Canal On large modern canals, especially very large ones such as ship canals , the gates and paddles are too large to be hand operated, and are operated by hydraulic or electrical equipment. On

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4368-414: The intermediate pounds have disappeared, and the upper gate of one lock is also the lower gate of the one above it. However, it is incorrect to use the terms staircase and flight interchangeably: because of the absence of intermediate pounds, operating a staircase is very different from operating a flight. It can be more useful to think of a staircase as a single lock with intermediate levels (the top gate

4452-514: The line at West Ham and opened on 14 May 1979 when the Crosstown Linkline service began between Camden Road and North Woolwich . The Crosstown Linkline was replaced with the electric North London Line service between Richmond and North Woolwich on 13 May 1985. In the 1990s, the station was comprehensively rebuilt as part of the Jubilee Line Extension , designed by van Heyningen and Haward Architects . A new bridge crosses four rail lines and

4536-450: The lock caused the upstream gates to slam shut, breaking them also, and sending a cascade of water over the boat, sinking it. This suspended navigation on the canal for 48 hours until the lock gates could be replaced and the boat removed from the lock. To economise, especially where good stone would be prohibitively expensive or difficult to obtain, composite locks were made, i.e. they were constructed using rubble or inferior stone, dressing

4620-413: The lock on their level and therefore set the lock in their favour – saving about 5 to 10 minutes. However, this is not true for staircase locks, where it is quicker for boats to go through in convoy, and it also uses less water. The rise is the change in water-level in the lock. The two deepest locks on the English canal system are Bath deep lock on the Kennet and Avon Canal and Tuel Lane Lock on

4704-459: The lock, together with the weir at Three Mills, was to lock out the tide just north of the House Mill . This means that this section of the Bow Back Rivers has ceased to be tidal. The lock was constructed so that barges from two large building projects (the London 2012 Olympics and Stratford City ) could pass through the lock, taking spoil out and delivering building materials on to the sites, via

4788-511: The middle of the Parish of West Ham in 1858. Before this, trains took a longer route via Stratford and Forest Gate to the north. The new line opened with stations initially at Bromley, Plaistow and East Ham. In November 1897 Arnold Hills , the owner of the Thames Ironworks and Shipbuilding Company , whose football team Thames Ironworks F.C. (which reformed in 1900 as West Ham United ) played at

4872-465: The nearby Stratford Market Depot . This is regularly used during peak times/at the end of the working day. Secondly, there is a crossover to the south of the DLR platforms so that trains can reverse early and head back south. Additionally there is a siding that opened in 2011 east of the sub-surface line platforms so that trains from both directions can terminate. On 15 March 1976, seven people were injured by

4956-452: The nearest London Underground stations . The nearest Docklands Light Railway stations are Bow Church and Pudding Mill Lane Lock (water transport) Locks are used to make a river more easily navigable, or to allow a canal to cross land that is not level. Later canals used more and larger locks to allow a more direct route to be taken. A pound lock is most commonly used on canals and rivers today. A pound lock has

5040-656: The new canal was low. This resulted in a sequential pair of locks, with gates pointing in opposite directions: one example was at Hall Green near Kidsgrove , where the southern terminus of the Macclesfield Canal joined the Hall Green Branch of the earlier Trent and Mersey Canal . The four gate stop lock near Kings Norton Junction, between the Stratford-upon-Avon Canal and the Worcester and Birmingham Canal

5124-590: The north-east. Since West Ham United Football Club moved to the Boleyn Ground in 1904, the station is no longer located near their home ground. East London Rugby Football Club is situated nearby on Holland Road, which is also home to Kings Cross Steelers RFC and Phantoms RFC. Services at West Ham are operated by c2c , Docklands Light Railway and London Underground on the District , Hammersmith & City and Jubilee lines. The typical off-peak service in trains per hour (tph) is: The station also served by

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5208-498: The platforms at peak times. c2c have proposed an escalator to replace the stairs. The construction of an additional platform for westbound trains would eliminate the problem. The station was temporarily modified to allow it to cope with an increase in passenger numbers during the London 2012 Olympic and Paralympic Games. A footbridge was constructed to connect the station to the Greenway foot and cycle path, which connects directly to

5292-461: The required level was reached, and then when the time came it was allowed to flow out. The water level could differ by 4 or 5 feet (1.2 or 1.5 m) at each lock and in the Grand Canal the level was raised in this way by 138 feet (42 m). In medieval Europe a sort of pound lock was built in 1373 at Vreeswijk , Netherlands. This pound lock serviced many ships at once in a large basin . Yet

5376-409: The sites of the London 2012 Olympics and Stratford City . The original Three Mills Lock was constructed in the 1930s as part of a scheme for flood prevention and the creation of employment. It bypassed the tide mills at Three Mills , and included a sluice structure, which was used to control water levels in the Bow Back Rivers. This structure became inoperative by the mid 1960s, and was removed in

5460-624: The solid part of the lock cill. On the Oxford Canal it is called a babbie; on the Grand Union Canal it is referred to as the cill bumper. Some canal operation authorities, primarily in the United States and Canada, call the ledge a miter sill (mitre sill in Canada). Gates are the watertight doors which seal off the chamber from the upper and lower pounds. Each end of the chamber is equipped with

5544-407: The spilled grain. In 984 Qiao installed a pair of sluice-gates two hundred and fifty feet apart, the entire structure roofed over like a building. By siting two staunch gates so close to one another, Qiao had created a short stretch of canal, effectively a pound-lock, filled from the canal above by raising individual wooden baulks in the top gate and emptied into the canal below by lowering baulks in

5628-411: The staircase by moving sideways around each other; or at peak times, one can have all the chambers full simultaneously with boats travelling in the same direction. When variable conditions meant that a higher water level in the new canal could not be guaranteed, then the older company would also build a stop lock (under its own control, with gates pointing towards its own canal) which could be closed when

5712-411: The station passed to the Midland Railway in 1912 and the London, Midland and Scottish Railway in 1923. The station was renamed West Ham (Manor Road) on 11 February 1924. When the North London Railway service to Plaistow ceased on 1 January 1916 the southern platforms were unused in normal service. The Metropolitan District Railway was incorporated into London Transport in 1933, and became known as

5796-483: The station was renamed back to West Ham on 1 January. On 15 March 1976, nine people were injured here by an explosion on a train by a member of the Provisional IRA . Julius Stephen, the driver of the train, was shot dead at the scene when he attempted to pursue the fleeing bomber. As part of the Jubilee Line Extension , the station was completely rebuilt, with reconstructed District and Hammersmith and City line platforms. In addition, platforms were re-established on

5880-419: The station. A double-ended centre siding east of West Ham was constructed to compensate for lost reversing capacity caused by the rebuilding of Whitechapel station as part of Crossrail work. This was commissioned on 17 January 2011. The Eastern Counties and Thames Junction Railway was constructed north to south through West Ham, linking Stratford with Canning Town in 1846. Platforms were constructed on

5964-413: The sump to a lower stream or drain, or (less wastefully) by pumping water back up to the canal. Particularly in the two-chamber type, there would be a need for a bypass culvert, to allow water to move along the interrupted pound and so supply locks further down the canal. In the case of the single-chamber type, this can be achieved by keeping the lock full and leaving the gates open while not in use. While

6048-488: The title for largest volume. In 2022 the IJmuiden sea lock serving the Port of Amsterdam became the world's largest lock by surface area. The lock is 500 m (1,600 ft) long, 70 m (230 ft) wide and has sliding lock gates creating a usable depth of 18 m (59 ft). The size of locks cannot be compared without considering the difference in water level that they are designed to operate under. For example,

6132-400: The top gate and raising ones in the lower. A turf-sided lock is an early form of canal lock design that uses earth banks to form the lock chamber, subsequently attracting grasses and other vegetation, instead of the now more familiar and widespread brick, stone, or concrete lock wall constructions. This early lock design was most often used on river navigations in the early 18th century before

6216-575: The upper level, the northern island platform (Platform 1 and 2) are used by District line and Hammersmith & City line trains, and the southern island platform (Platforms 7 and 8) are used by c2c trains. At the lower level, the western island platform (Platforms 5 and 6) are used by Jubilee line trains, with the eastern island platform (Platforms 3 and 4) - formerly the North London line platforms - are now used by Docklands Light Railway trains. Jubilee line trains can terminate here to enter into

6300-404: The upstream lock to give them an extra heavy swell, which consisted of opening all the paddles on the lock gate, creating a surge that affected the whole pound below. On the Erie Canal, some loaded boats needed a swell to get out of the lock. Particularly lumber boats, being top heavy, would list to one side and get stuck in the lock, and needed a swell to get them out. Some lockkeepers would give

6384-718: The waterways. With the selection of the island formed by the City Mills River and the Lee Navigation as the main site for the 2012 London Olympics , restoration of the Bow Back Rivers was considered an important part of the development, as it would allow construction materials to be delivered by barge. A new lock and sluice structure was designed for the Prescott Channel, along with the Three Mills Wall River Weir to prevent tidal water flowing backwards through

6468-405: The windlass (or handle) out of one's hands, or if one was standing in the wrong place, could knock one into the canal, leading to injuries and drownings. On the Chesapeake and Ohio Canal, the lockkeepers were required to remove the windlasses from all lock paddles at night, to prevent unauthorized use. A swell was caused by opening suddenly the paddle valves in the lock gates, or when emptying

6552-456: Was all that need be emptied when a boat passed through. This type of lock, called a pound lock was known in Imperial China and ancient Europe and was used by Greek engineers in the Canal of the Pharaohs under Ptolemy II (284 to 246 BC), when engineers solved the problem of overcoming the difference in height through canal locks . Pound locks were first used in medieval China during

6636-416: Was also a doubled set of locks. Five twinned locks allowed east- and west-bound boats to climb or descend the 60 feet (18 m) Niagara Escarpment , a considerable engineering feat in the nineteenth century. While Lockport today has two large steel locks, half of the old twin stair acts as an emergency spillway and can still be seen, with the original lock gates having been restored in early 2016. Loosely,

6720-503: Was by van Heyningen and Haward Architects , with the District and Hammersmith and City line platforms designed by Jestico + Whiles . The station design was considered to evoke work by Charles Holden in the 1930s, with use of brick and glass blocks, as well as a clock tower. The station was designed in 27 weeks, and was the cheapest of the new stations to be built. Critics called the station "effortlessly elegant" and an "impressive architectural essay in brick, concrete and glass". It

6804-560: Was completed in May 1900, but did not open until 1 February 1901. The station was initially known as West Ham. The North London Railway had run a daily service to Plaistow via the Bow-Bromley curve since 18 May 1869 and when West Ham opened it used the northern platforms. In 1905 they switched to the southern platforms, with the opening of a new bay platform at Plaistow on the southern side. The Whitechapel and Bow Railway allowed through services of

6888-417: Was later awarded a Royal Fine Art Commission Trust Award. The station consists of four sets of island platforms , two on an elevated east–west alignment and another perpendicular pair at street level, giving a total of eight platform faces. The existing entrance was closed, with the old ticket hall refurbished to become a connecting concourse to the District and Hammersmith & City line platforms and

6972-412: Was opened in 1901 by the London, Tilbury and Southend Railway on the route from Fenchurch Street to Barking. In the late 1990s, the station was rebuilt and significantly expanded as part of the Jubilee Line Extension , fully opening in 1999. The station is in London fare zone 2 and zone 3 . The London, Tilbury and Southend Railway direct line from Bow to Barking was constructed east to west through

7056-588: Was replaced in 1914 by a pair of guillotine lock gates which stopped the water flow regardless of which canal was higher. These gates have been permanently open since nationalisation. The best known example of a round lock is the Agde Round Lock on the Canal du Midi in France. This serves as a lock on the main line of the canal and allows access to the Hérault River . A second French round lock can be found in

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