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51-656: The Anderton Boat Lift is a two- caisson lift lock near the village of Anderton , Cheshire , in North West England . It provides a 50-foot (15.2 m) vertical link between two navigable waterways: the River Weaver and the Trent and Mersey Canal . The structure is designated as a scheduled monument , and is included in the National Heritage List for England ; it is also known as one of

102-570: A GPS survey enable engineers to position a box caisson with pinpoint accuracy. An open caisson is similar to a box caisson, except that it does not have a bottom face. It is suitable for use in soft clays (e.g. in some river-beds), but not for where there may be large obstructions in the ground. An open caisson that is used in soft grounds or high water tables, where open trench excavations are impractical, can also be used to install deep manholes, pump stations and reception/launch pits for microtunnelling , pipe jacking and other operations. A caisson

153-409: A barge with a beam of up to 13 feet (4.0 m). Each caisson weighed 90 long tons (91 tonnes ; 100 short tons ) when empty and 252 long tons (256 t; 282 short tons) when full of water (because of displacement , the weight is the same with or without boats). Each caisson was supported by a single hydraulic ram consisting of a hollow 50 ft (15.2 m) long cast iron vertical piston with

204-614: A basin was excavated on the north bank of the Weaver at Anderton that took the river to the foot of the escarpment of the canal – 50 ft (15.2 m) above. The Anderton Basin was owned and operated by the Weaver Navigation Trustees. Facilities were built to trans-ship goods between the waterways including two cranes , two salt chutes and an inclined plane that was possibly inspired by the much larger Hay Inclined Plane at Coalport . The facilities were extended when

255-545: A caisson, as opposed to three minutes in normal operation. In October 1871 the Weaver Navigation Trustees held a special general meeting which resolved "to consider the desirability of constructing a lift with basins and all other requisite works for the interchange of traffic between the River Weaver and the North Staffordshire Canal at Anderton and of applying to Parliament for an Act to authorise

306-401: A coffee shop and information and films about the history of the lift. The visitor centre incorporates the new lift control centre. Although a modified version of the original hydraulic system was reinstated, the 1906–08 external frame and pulleys have been retained in a non-operational role. The weights that used to counterbalance the caissons were not rehung, but have been used to build a maze in

357-437: A diameter of 3 ft (0.9 m), in a buried 50 ft (15.2 m) long cast iron vertical cylinder with a diameter of 5 feet 6 inches (1.68 m). At river level the caissons sat in a water-filled sandstone lined chamber. Above ground the superstructure consisted of seven hollow cast iron columns which provided guide rails for the caissons and supported an upper working platform, walkways and access staircase. At

408-639: A second quay was built in 1801 and a second entrance to the basin was constructed in 1831. By 1870 the Anderton Basin was a major interchange for trans-shipping goods in both directions, with extensive warehousing, three double inclined planes and four salt chutes. Trans-shipment was time-consuming and expensive, and the Trustees of the Weaver Navigation decided a link between the waterways was needed to allow boats to pass directly from one to

459-437: A system of counterweights and overhead pulleys that would allow the caissons to operate independently of each other. Although this solution involved many more moving parts than the hydraulic system these would be above ground and accessible thus making maintenance easier and cheaper and have a longer working life. Other advantages of the conversion listed by Saner included a reduction in the number of operating attendants by one and

510-415: A total of 49 days. The converted lift was formally opened on 29 July 1908 (although one caisson had been carrying traffic on electrical power since May 1908 while the second caisson was converted). After conversion to electrical operation the boat lift was operated successfully for 75 years. Regular maintenance was still necessary; for example, the wire ropes supporting the caissons suffered from fatigue from

561-452: A working fluid in the hydraulic system and the immersion of the pistons in the wet dock at river level led to corrosion and "grooving" of the pistons. Attempts to repair the grooves with copper made matters worse as it reacted electrolytically with the acidic canal water and hastened corrosion of the surrounding iron. In 1897 the lift was converted to use distilled water as its working fluid, slowing corrosion, but not stopping it completely. Over

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612-513: Is a prefabricated concrete box (with sides and a bottom); it is set down on prepared bases. Once in place, it is filled with concrete to become part of the permanent works, such as the foundation for a bridge pier. Hollow concrete structures are usually less dense than water so a box caisson must be ballasted or anchored to keep it from floating until it can be filled with concrete. Sometimes elaborate anchoring systems may be required, such as in tidal zones . Adjustable anchoring systems combined with

663-559: Is excavated by clamshell excavator bucket on crane. The formation level subsoil may still not be suitable for excavation or bearing capacity . The water in the caisson (due to a high water table) balances the upthrust forces of the soft soils underneath. If dewatered, the base may "pipe" or "boil", causing the caisson to sink. To combat this problem, piles may be driven from the surface to act as: H-beam sections (typical column sections, due to resistance to bending in all axis) may be driven at angles "raked" to rock or other firmer soils;

714-407: Is lowered underwater, then the ship is floated above the support, and finally the platform with support and ship is lifted and the ship is brought to the level of the quay . Shiplifts are often supplied under rules of a classification authority. Lloyd's Register of Shipping is the authority with most experience in the certification or classification of shiplifts. Whereas "shiplift" is the word that

765-400: Is normally used, the term used by Lloyd's register is "Mechanical Lift Dock". There are two different kinds of platform design, the articulated and the rigid. The articulated platform has hinged connections between the main and the longitudinal beams. A rigid platform, the beams are bolted or welded together. The Syncrolift System was invented by Raymond Pearlson , who was later awarded

816-466: Is required. Shallow caissons may be open to the air, whereas pneumatic caissons (sometimes called pressurized caissons ), which penetrate soft mud , are bottomless boxes sealed at the top and filled with compressed air to keep water and mud out at depth. An airlock allows access to the chamber. Workers, called sandhogs in American English, move mud and rock debris (called muck ) from

867-520: Is sunk by self-weight, concrete or water ballast placed on top, or by hydraulic jacks. The leading edge (or cutting shoe ) of the caisson is sloped out at a sharp angle to aid sinking in a vertical manner; it is usually made of steel. The shoe is generally wider than the caisson to reduce friction, and the leading edge may be supplied with pressurised bentonite slurry, which swells in water, stabilizing settlement by filling depressions and voids. An open caisson may fill with water during sinking. The material

918-576: The Association of Waterways Cruising Clubs , British Waterways and the Trent and Mersey Canal Society. Heritage Lottery Funding contributed £3.3 million, and more than 2,000 individuals contributed to the scheme, raising a further £430,000. Restoration commenced in 2000 and the lift was re-opened to boat traffic in March 2002. The site now includes a two-storey visitor centre and exhibition building with

969-723: The Cheshire Plain since Roman times. By the end of the 17th century a major salt mining industry had developed around the Cheshire "salt towns" of Northwich , Middlewich , Nantwich and Winsford . Completion of the River Weaver Navigation in 1734 provided a navigable route for transporting salt from Winsford, through Northwich, to Frodsham , where the Weaver joins the River Mersey . The River Weaver Navigation Act 1759 ( 33 Geo. 2 . c. 49) appointed

1020-554: The Eads Bridge (completed in 1874), and the Brooklyn Bridge (completed in 1883). To install a caisson in place, it is brought down through soft mud until a suitable foundation material is encountered. While bedrock is preferred, a stable, hard mud is sometimes used when bedrock is too deep. The four main types of caisson are box caisson , open caisson , pneumatic caisson and monolithic caisson . A box caisson

1071-767: The Royal Victoria Dock in London, designed by experienced hydraulic engineer Edwin Clark . Having decided on a hydraulic ram design Leader Williams appointed Edwin Clark as principal designer. At that time the Anderton Basin consisted of a cut on the north bank of the Weaver surrounding a small central island. Clark decided to build the boat lift on this island. The wrought iron caissons were 75 ft (22.9 m) long by 15 ft 6 in (4.72 m) wide by 9 ft 6 in (2.90 m) deep, and could each accommodate two 72 ft (21.9 m) narrowboats or

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1122-555: The pressurized environment of the caisson must decompress at a rate that allows symptom-free release of inert gases dissolved in the body tissues if they are to avoid decompression sickness , a condition first identified in caisson workers, and originally named "caisson disease" in recognition of the occupational hazard. Construction of the Brooklyn Bridge , which was built with the help of pressurised caissons, resulted in numerous workers being either killed or permanently injured by caisson disease during its construction. Barotrauma of

1173-518: The H-beams are left extended above the base. A reinforced concrete plug may be placed under the water, a process known as tremie concrete placement . When the caisson is dewatered, this plug acts as a pile cap, resisting the upward forces of the subsoil. A monolithic caisson (or simply a monolith ) is larger than the other types of caisson, but similar to open caissons. Such caissons are often found in quay walls, where resistance to impact from ships

1224-835: The Seven Wonders of the Waterways. Built in 1875, the boat lift was in use for over 100 years until it was closed in 1983 due to corrosion. Restoration started in 2001 and the boat lift was re-opened in 2002. The lift and associated visitor centre and exhibition are operated by the Canal & River Trust . It is one of only two working boat lifts in the United Kingdom; the other is the Falkirk Wheel in Scotland . Salt has been extracted from rock salt beds underneath

1275-526: The Sperry Award for the invention, development and worldwide implementation of a new system for lifting ships out of the water for repair and for launching new ship construction. . Many shiplifts use a transfer system for ships so that the vessels can be transported from the water to a parking place where they can be painted or repaired. One shiplift can serve many parking places, while a dry docking installation can only dock one ship. For large vessels

1326-464: The Trustees of the Weaver Navigation and gave them responsibility for maintaining and operating the route. The opening of the Trent and Mersey Canal in 1777 provided a second route close to the Weaver Navigation for part of its length, but extended further south to the coal mining and pottery industries around Stoke-on-Trent . Rather than competing with each other the owners of the two waterways decided it would be more profitable to work together. In 1793

1377-472: The avoidance of costly boiler repairs. Saner promised to achieve the conversion with only three short periods of closure to traffic. This was important because it minimised disruption to traffic and the loss of revenue during conversion. As a result, the weight of the caissons and counterweights would now be borne by the lift superstructure instead of by the rams. The superstructure was therefore strengthened and put on stronger foundations. The new superstructure

1428-435: The base of the caisson. When the caisson hits bedrock, the sandhogs exit through the airlock and fill the box with concrete, forming a solid foundation pier. A pneumatic (compressed-air) caisson has the advantage of providing dry working conditions, which is better for placing concrete. It is also well suited for foundations for which other methods might cause settlement of adjacent structures. Construction workers who leave

1479-437: The caissons via an overhead balance wheel. It had a solid masonry superstructure to support the weight of the loaded caissons. Leader Williams realised that if he used water-filled hydraulic rams to support the caissons their weight would be borne by the rams and their cylinders, buried underground and a much lighter superstructure could be used. He may have been inspired by inspecting a hydraulic ship lift and graving dock at

1530-524: The construction of such works." In July 1872 royal assent was granted for the Weaver Navigation Act 1872 ( 35 & 36 Vict. c. xcviii), which authorised the construction of the boat lift. The contract for its construction was awarded to Emmerson, Murgatroyd & Co. of Stockport and Liverpool . Work started before the end of 1872 and took 30 months. The Anderton Boat Lift was formally opened to traffic on 26 July 1875. The total cost

1581-399: The ears, sinus cavities and lungs and dysbaric osteonecrosis are other risks. Ship lift A shiplift is a modern alternative for a slipway , a floating dry dock or a graving dry dock . A shiplift is used to dry dock and launch ships . It consists of a structural platform that is lifted and lowered exactly vertically, synchronously by a number of hoists . First, the platform

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1632-415: The edge of the workspace to a water-filled pit, connected by a tube (called the muck tube ) to the surface. A crane at the surface removes the soil with a clamshell bucket . The water pressure in the tube balances the air pressure, with excess air escaping up the muck tube. The pressurized air flow must be constant to ensure regular air changes for the workers and prevent excessive inflow of mud or water at

1683-414: The grounds of the visitor centre. Further restoration work is now planned starting in mid-2025 and continuing for 12–18 months. During this time, the lift will be closed. 53°16′22″N 2°31′50″W  /  53.2728°N 2.5305°W  / 53.2728; -2.5305 Caisson (engineering)#Boat lift caissons Caissons are constructed in such a way that the water can be pumped out, keeping

1734-411: The need to close the lift entirely. During 1941 and 1942 the hydraulic rams of the original lift, which had been left in place in a shaft beneath the dry dock, were removed to salvage the iron. During the 1950s and 1960s commercial traffic on British canals declined. By the 1970s the lift's traffic was almost entirely recreational and the lift was hardly used during winter months. The new superstructure

1785-429: The new foundations and superstructure, the wet dock at river level was also converted into a dry dock and the aqueduct between the lift and the canal was strengthened. The original caissons were retained but were modified to take the wire ropes that now supported them on each side. Conversion was carried out between 1906 and 1908. As Saner had promised, the lift was only closed for three periods during these two years, for

1836-485: The next few years maintenance and repairs took place with increasing frequency, requiring complete closure of the lift for several weeks or a period of reduced and slower operation with a single caisson. By 1904 the Weaver Navigation Trustees faced the prospect of closing the boat lift for a considerable period to repair the hydraulic rams. They asked their Chief Engineer Colonel J. A. Saner, to investigate alternatives to hydraulic operation. Saner proposed electric motors and

1887-516: The other. A flight of locks was considered but discarded, mainly because of the lack of a suitable site and the loss of water that would have resulted from using them. In 1870 the Trustees proposed a boat lift between the waterways at the Anderton Basin. The Trustees approached the North Staffordshire Railway Company , owners of the Trent and Mersey Canal, to ask for a contribution towards the cost. When this approach

1938-414: The pulleys to 36 cast iron counterweights weighing 14 long tons (14 t; 16 short tons) each, 18 on each side to balance the 252 long tons (256 t; 282 short tons) weight of each loaded caisson. The electric motor had to overcome friction between the pulleys and their bearings. A 30 horsepower (22 kW) motor was installed, but normal operation only required about half of this power. In addition to

1989-435: The repeated bending and straightening as they ran over the overhead pulleys and had to be replaced frequently. However, maintenance was simpler than before the conversion because the mechanism of the electrical lift was above ground. Maintenance was also less expensive because the caissons were now designed to be run independently, allowing most maintenance to be carried out while one caisson remained operational and thus avoiding

2040-399: The start and end of a lift either cylinder could be operated independently, powered by an accumulator or pressure vessel at the top of the lift structure, which was kept primed by a 10 horsepower (7.5 kW) steam engine. If necessary, the steam engine and accumulator could operate either hydraulic ram independently to raise the caissons, although in this mode it took about 30 minutes to raise

2091-400: The transfer system consists of a number of trolleys or cradles, supported by high capacity steel wheels. The wheels drive on heavy duty rails. The transport can be one directional, but in order to serve more parking places, two directional systems are used. These two directional systems make use of a traverser carriage or sometimes the wheels of the trolleys can be turned over 90 degrees. Above

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2142-426: The upper level the boat lift was connected to the Trent and Mersey canal via a 165 ft (50.3 m) long wrought iron aqueduct , with vertical wrought iron gates at either end. In normal operation the cylinders of the hydraulic rams were connected by a 5 in (130 mm) diameter pipe that allowed water to pass between them, thus lowering the heavier caisson and raising the lighter one. To make adjustments at

2193-437: The water-filled dock at river level softened the impact. No-one was hurt and there was no damage to the lift's superstructure. As a precaution, tests were carried out on the second hydraulic cylinder. During these tests the second cylinder failed too. As a result, the boat lift was closed for six months while sections of both cylinders were replaced and the connecting pipework, which was thought to have contributed to their failure,

2244-400: The wheels often hydraulic cylinders are located so that the ship can be transported upon a so-called Syncrolift® Fluid Bed™. The cylinders are also used to lower the ships on a static support, so that the transfer system with the active elements can be recovered. Smaller devices called " Boat lifts " are available that simply raise yachts, sailboats, or small watercraft above the water level at

2295-498: The work environment dry. When piers are being built using an open caisson, and it is not practical to reach suitable soil, friction pilings may be driven to form a suitable sub-foundation. These piles are connected by a foundation pad upon which the column pier is erected. Caisson engineering has been used since at least the 19th century, with three prominent examples being the Royal Albert Bridge (completed in 1859),

2346-449: Was built around the original lift frame in order to avoid the need to dismantle the original lift, which would have taken it out of service for a long period. The new superstructure consisted of ten steel A-frames, five on each side, supporting a machinery deck 60 ft (18 m) above the river level where the electric motors, drive shafts and cast-iron headgear pulleys were mounted. Wire ropes attached to both sides of each caisson passed over

2397-684: Was originally intended to restore the lift to electrical operation but after consultation with English Heritage , in 1997 it was decided to restore the lift to hydraulic operation using hydraulic oil . To raise the £7 million restoration cost, a partnership was forged between the Waterways Trust , the Inland Waterways Association , the Anderton Boat Lift Trust , the Friends of Anderton Boat Lift,

2448-430: Was redesigned. The volume of traffic through the lift grew steadily through the 1880s and 90s but the hydraulic cylinders continued to cause problems. The gland of one cylinder (where the piston travelled through the cylinder wall) was temporarily repaired in 1887 and replaced in 1891, and the gland of the other cylinder was replaced in 1894. The main cause for concern was corrosion of the pistons. The use of canal water as

2499-403: Was susceptible to corrosion and the entire lift was painted with a protective solution of tar and rubber that had to be renewed every eight years or so. In 1983, during repainting, extensive corrosion was found in the superstructure and it was declared structurally unsound and closed. During the 1990s British Waterways carried out preliminary investigations before launching a restoration bid. It

2550-500: Was unsuccessful the Trustees decided to fund the project themselves. The Trustees asked their Chief Engineer, Edward Leader Williams , to draw up plans for a boat lift. He settled on a design involving a pair of water-filled caissons that would counterbalance one another and require relatively little power to lift boats up and down. A similar boat lift on the Grand Western Canal , completed in 1835, used chains to connect

2601-400: Was £48,428 (£5,763,000 at today's prices). For five years the boat lift operated successfully, the longest closures being during spells of cold weather when the canal froze over. In 1882 a cast iron hydraulic cylinder burst while the caisson it supported was at canal level with a boat in it. The caisson descended rapidly, but water escaping from the burst cylinder slowed the rate of descent and

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