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85-609: The Royal Albert Bridge is a railway bridge which spans the River Tamar in England between Plymouth , Devon and Saltash , Cornwall . Its unique design consists of two 455-foot (138.7 m) lenticular iron trusses 100 feet (30.5 m) above the water, with conventional plate-girder approach spans. This gives it a total length of 2,187.5 feet (666.8 m). It carries the Cornish Main Line railway in and out of Cornwall. It

170-596: A bridge-restaurant which is a bridge built to serve as a restaurant. Other suspension bridge towers carry transmission antennas. Conservationists use wildlife overpasses to reduce habitat fragmentation and animal-vehicle collisions. The first animal bridges sprung up in France in the 1950s, and these types of bridges are now used worldwide to protect both large and small wildlife. Bridges are subject to unplanned uses as well. The areas underneath some bridges have become makeshift shelters and homes to homeless people, and

255-459: A "reserve" track that can allow a reduced capacity service to continue if one track is closed. If a single-track line is designed to be used by more than one train at a time, it must have passing loops (also called passing sidings or crossing loops ) at intervals along the line to allow trains running in different directions to pass each other. These consist of short stretches of double track, usually long enough to hold one train. The capacity of

340-520: A bridge is to be designed, standards authorities specify simplified notional load models, notably HL-93, intended to give the same load effects as the characteristic maximum values. The Eurocode is an example of a standard for bridge traffic loading that was developed in this way. Most bridge standards are only applicable for short and medium spans - for example, the Eurocode is only applicable for loaded lengths up to 200 m. Longer spans are dealt with on

425-471: A case-by-case basis. It is generally accepted that the intensity of load reduces as span increases because the probability of many trucks being closely spaced and extremely heavy reduces as the number of trucks involved increases. It is also generally assumed that short spans are governed by a small number of trucks traveling at high speed, with an allowance for dynamics. Longer spans on the other hand, are governed by congested traffic and no allowance for dynamics

510-480: A combination of structural health monitoring and testing. This is regulated in country-specific engineer standards and includes an ongoing monitoring every three to six months, a simple test or inspection every two to three years and a major inspection every six to ten years. In Europe, the cost of maintenance is considerable and is higher in some countries than spending on new bridges. The lifetime of welded steel bridges can be significantly extended by aftertreatment of

595-399: A different site, and re-used. They are important in military engineering and are also used to carry traffic while an old bridge is being rebuilt. Movable bridges are designed to move out of the way of boats or other kinds of traffic, which would otherwise be too tall to fit. These are generally electrically powered. The Tank bridge transporter (TBT) has the same cross-country performance as

680-404: A double track timber structure and instead proposed a single track wrought iron design consisting of a single 850-foot (259.1 m) span. As the cost of this structure would have been around £500,000 at 1846 prices (equivalent to £61,160,000 in 2023), he amended the design to one of two main spans of 455 feet (138.7 m) with 100 feet (30.5 m) clearance above mean high spring tide ; this

765-594: A few will predominate. The separation of forces and moments may be quite clear. In a suspension or cable-stayed bridge , the elements in tension are distinct in shape and placement. In other cases the forces may be distributed among a large number of members, as in a truss. The world's longest beam bridge is Lake Pontchartrain Causeway in southern Louisiana in the United States, at 23.83 miles (38.35 km), with individual spans of 56 feet (17 m). Beam bridges are

850-501: A main truss of 300 feet (91 m) with a curving tubular main member and three conventional plate-girder approach spans of 100 feet (30 m), a similar solution to that adopted for crossing the River Tamar at Saltash. The river is about 1,100 feet (340 m) wide at Saltash. Brunel's first thoughts had been to cross this on a double track timber viaduct with a central span of 255 feet (78 m) and six approach spans of 105 feet (32 m) with 80 feet (24 m) clearance above

935-405: A new track layout. The remaining approach spans were replaced on both sides of the river during 1928 and 1929. During the 1930s new cross-bracing and diagonal sway-bracing were added between the vertical standards to further strengthen the bridge and keep the suspension chains hanging in the correct shape. The bridge was Grade 1 listed in 1952. Additional links between the suspensions chains and

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1020-553: A simple type of suspension bridge , were used by the Inca civilization in the Andes mountains of South America, just prior to European colonization in the 16th century. The Ashanti built bridges over streams and rivers . They were constructed by pounding four large forked tree trunks into the stream bed, placing beams along these forked pillars, then positioning cross-beams that were finally covered with four to six inches of dirt. During

1105-606: A single-track line is determined by the number of passing loops. Passing loops may also be used to allow trains heading in the same direction at different speeds to overtake. In some circumstances on some isolated branch lines with a simple shuttle service (such as the Abbey Line in Great Britain or L202 railway in Croatia) a single-track line may work under the "one train working" principle without passing loops, where only one train

1190-541: A single-track railway to double track is called duplication or doubling; converting double track to single track is known as singling. A double-track railway operating only a single track is known as single-line working . Kirkby railway station (until 1977) and Ormskirk railway station (until 1970) were double-track railway , when they were converted into single-track railway with cross-platform interchange . Building bike trails on rail corridors has occurred in limited examples; however, developing rail rights of way for

1275-526: A small fund was allowed for Brunel to continue the survey. The cylinder was positioned at 35 different places and a total of 175 borings made. In 1853 the tenders for the bridge were considered by the Cornwall Railway Board, and it was decided to let the work to Charles John Mare , a shipbuilder from Blackwall who had built the ironwork for the Britannia Bridge . The fee he sought for building

1360-578: A span of 552 m (1,811 ft). The bridge was opened 29 April 2009, in Chongqing , China. The longest suspension bridge in the world is the 4,608 m (15,118 ft) 1915 Çanakkale Bridge in Turkey. The longest cable-stayed bridge since 2012 is the 1,104 m (3,622 ft) Russky Bridge in Vladivostok , Russia. Some Engineers sub-divide 'beam' bridges into slab, beam-and-slab and box girder on

1445-732: A stream. Often in palaces, a bridge will be built over an artificial waterway as symbolic of a passage to an important place or state of mind. A set of five bridges cross a sinuous waterway in an important courtyard of the Forbidden City in Beijing, China. The central bridge was reserved exclusively for the use of the Emperor and Empress, with their attendants. The estimated life of bridges varies between 25 and 80 years depending on location and material. Bridges may age hundred years with proper maintenance and rehabilitation. Bridge maintenance consisting of

1530-479: A tank even when fully loaded. It can deploy, drop off and load bridges independently, but it cannot recover them. Double-decked (or double-decker) bridges have two levels, such as the George Washington Bridge , connecting New York City to Bergen County , New Jersey , US, as the world's busiest bridge, carrying 102 million vehicles annually; truss work between the roadway levels provided stiffness to

1615-535: A total length for the nineteen spans of 2,187.5 feet (666.8 m). The first work was to properly survey the river bed. On 26 April 1848 a 6-foot (1.8 m) iron cylinder 85 feet (25.9 m) tall was launched into the Tamar. From the bottom of this the bed of the river could be examined to identify its nature and the location of solid foundations. The Cornwall Railway at this time was finding it difficult to raise funds and so most operations were suspended that summer, but

1700-456: Is a bridge that carries water, resembling a viaduct, which is a bridge that connects points of equal height. A road-rail bridge carries both road and rail traffic. Overway is a term for a bridge that separates incompatible intersecting traffic, especially road and rail. Some bridges accommodate other purposes, such as the tower of Nový Most Bridge in Bratislava , which features a restaurant, or

1785-514: Is adjacent to the Tamar Bridge which opened in 1961 to carry the A38 road . The Royal Albert Bridge was designed by Isambard Kingdom Brunel . Surveying started in 1848 and construction commenced in 1854. The first main span was positioned in 1857 and the completed bridge was opened by Prince Albert on 2 May 1859. Brunel died later that year and his name was then placed above the portals at either end of

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1870-421: Is allowed on the line at a time. On single-track lines with passing loops, measures must be taken to ensure that only one train in one direction can use a stretch of single track at a time, as head-on collisions are a particular risk. Some form of signalling system is required. In traditional British practice (and countries using British practice), single-track lines were operated using a token system where

1955-574: Is an early example of a double-decked bridge. The upper level carries a railway, and the lower level is used for road traffic. Other examples include Britannia Bridge over the Menai Strait and Craigavon Bridge in Derry, Northern Ireland. The Oresund Bridge between Copenhagen and Malmö consists of a four-lane highway on the upper level and a pair of railway tracks at the lower level. Tower Bridge in London

2040-485: Is different example of a double-decked bridge, with the central section consisting of a low-level bascule span and a high-level footbridge . A viaduct is made up of multiple bridges connected into one longer structure. The longest and some of the highest bridges are viaducts, such as the Lake Pontchartrain Causeway and Millau Viaduct . A multi-way bridge has three or more separate spans which meet near

2125-417: Is led by architects, bridges are usually designed by engineers. This follows from the importance of the engineering requirements; namely spanning the obstacle and having the durability to survive, with minimal maintenance, in an aggressive outdoor environment. Bridges are first analysed; the bending moment and shear force distributions are calculated due to the applied loads. For this, the finite element method

2210-540: Is needed. Calculating the loading due to congested traffic remains a challenge as there is a paucity of data on inter-vehicle gaps, both within-lane and inter-lane, in congested conditions. Weigh-in-Motion (WIM) systems provide data on inter-vehicle gaps but only operate well in free flowing traffic conditions. Some authors have used cameras to measure gaps and vehicle lengths in jammed situations and have inferred weights from lengths using WIM data. Others have used microsimulation to generate typical clusters of vehicles on

2295-403: Is the backdrop of ITV1's The West Country Tonight during the old westcountry region. Special occasions have been marked over the years by special events: Railway bridge A bridge is a structure built to span a physical obstacle (such as a body of water , valley , road, or railway) without blocking the path underneath. It is constructed for the purpose of providing passage over

2380-737: Is the most popular. The analysis can be one-, two-, or three-dimensional. For the majority of bridges, a two-dimensional plate model (often with stiffening beams) is sufficient or an upstand finite element model. On completion of the analysis, the bridge is designed to resist the applied bending moments and shear forces, section sizes are selected with sufficient capacity to resist the stresses. Many bridges are made of prestressed concrete which has good durability properties, either by pre-tensioning of beams prior to installation or post-tensioning on site. In most countries, bridges, like other structures, are designed according to Load and Resistance Factor Design (LRFD) principles. In simple terms, this means that

2465-594: The Board of Trade on 20 April 1859. He ran a heavy train over the bridge and measured deflections in the main trusses of 1.14 inches (29 mm) in the Devon truss, and 1.20 inches (30 mm) in the Cornwall one. Overall he described it as 'highly satisfactory'. Prince Albert had agreed to the bridge being named after him as early as 1853. He was invited to perform the opening ceremony, and on 2 May 1859 he travelled from Windsor on

2550-618: The Hellenistic era can be found in the Peloponnese. The greatest bridge builders of antiquity were the ancient Romans . The Romans built arch bridges and aqueducts that could stand in conditions that would damage or destroy earlier designs, some of which still stand today. An example is the Alcántara Bridge , built over the river Tagus , in Spain. The Romans also used cement, which reduced

2635-554: The Royal Train . Several thousand spectators attended that day, although guests from Cornwall were late for the ceremony as their train broke down at Liskeard . Illness prevented the attendance of Brunel who was instead represented by his chief assistant Robert Brereton . Public services commenced on 4 May 1859. After Brunel's premature death on 15 September 1859 the directors of the Cornwall Railway Company decided to make

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2720-833: The University of Minnesota ). Likewise, in Toronto , the Prince Edward Viaduct has five lanes of motor traffic, bicycle lanes, and sidewalks on its upper deck; and a pair of tracks for the Bloor–Danforth subway line on its lower deck. The western span of the San Francisco–Oakland Bay Bridge also has two levels. Robert Stephenson 's High Level Bridge across the River Tyne in Newcastle upon Tyne , completed in 1849,

2805-495: The river Severn . With the Industrial Revolution in the 19th century, truss systems of wrought iron were developed for larger bridges, but iron does not have the tensile strength to support large loads. With the advent of steel, which has a high tensile strength, much larger bridges were built, many using the ideas of Gustave Eiffel . In Canada and the United States, numerous timber covered bridges were built in

2890-521: The 13th century BC, in the Peloponnese is one of the oldest arch bridges in existence and use. The Oxford English Dictionary traces the origin of the word bridge to an Old English word brycg , of the same meaning.   The Oxford English Dictionary also notes that there is some suggestion that the word can be traced directly back to Proto-Indo-European *bʰrēw-. However, they also note that "this poses semantic problems." The origin of

2975-511: The 18th century, there were many innovations in the design of timber bridges by Hans Ulrich Grubenmann , Johannes Grubenmann , as well as others. The first book on bridge engineering was written by Hubert Gautier in 1716. A major breakthrough in bridge technology came with the erection of the Iron Bridge in Shropshire, England in 1779. It used cast iron for the first time as arches to cross

3060-507: The Cornish side there are ten which measure (from Saltash station towards the river): 67.5 feet (20.6 m), five of 69.5 feet (21.2 m), 72.5 feet (22.1 m), 78.0 feet (23.8 m), 83.5 feet (25.5 m), 93.0 feet (28.3 m), and seven on the Devon side (from the river towards St Budeaux): 93.0 feet (28.3 m), 83.5 feet (25.5 m), 78.0 feet (23.8 m), 72.5 feet (22.1 m) and three of 69.5 feet (21.2 m). This gives

3145-451: The Devon shore with a jetty and workshops. He then proceeded to construct a 37-foot (11.3 m) iron cylinder 90 feet (27.4 m) tall which was to form the work base for the construction of the central pier. This was launched in May 1854 and moored in the centre of the river between four pontoons. The bottom had been shaped to follow the rock surveyed in 1848. Once it was settled on the river bed

3230-461: The Saltash Bridge was £162,000, but on 21 September 1855 while constructing the first of the two trusses he filed for bankruptcy. Brunel proposed that the company should complete this first truss itself by its own direct labour, to which the company agreed. A contract for the remainder of the building was awarded to Messrs Hudson and Male. Mare's first task had been to establish an erecting yard on

3315-610: The appearance of the bridge can have great importance. Often, this is the case with a large bridge that serves as an entrance to a city, or crosses over a main harbor entrance. These are sometimes known as signature bridges. Designers of bridges in parks and along parkways often place more importance on aesthetics, as well. Examples include the stone-faced bridges along the Taconic State Parkway in New York. Bridges are typically more aesthetically pleasing if they are simple in shape,

3400-613: The attention of the general public in the 1990s by the novel, movie and play The Bridges of Madison County . In 1927, welding pioneer Stefan Bryła designed the first welded road bridge in the world, the Maurzyce Bridge which was later built across the river Słudwia at Maurzyce near Łowicz , Poland in 1929. In 1995, the American Welding Society presented the Historic Welded Structure Award for

3485-455: The attention of the general public. The launching of the Cornish span in 1857 attracted a crowd of around 20,000, with similar numbers said to have witnessed the launch of the Devonport span and the opening day. During its construction it was photographed many times and after its opening it was the subject for many paintings, including those by Devonport-born artist Alfred Wallis . It has also been

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3570-596: The basis of their cross-section. A slab can be solid or voided (though this is no longer favored for inspectability reasons) while beam-and-slab consists of concrete or steel girders connected by a concrete slab. A box-girder cross-section consists of a single-cell or multi-cellular box. In recent years, integral bridge construction has also become popular. Most bridges are fixed bridges, meaning they have no moving parts and stay in one place until they fail or are demolished. Temporary bridges, such as Bailey bridges , are designed to be assembled, taken apart, transported to

3655-414: The bridge a memorial to him by adding the words I.K. BRUNEL, ENGINEER, 1859 in large metal letters on either end of the bridge. In 1921, new access platforms were added that obscured the lettering but in 2006 Network Rail relocated the platforms, allowing the name to be clearly seen again. The walkways had previously been temporarily removed in 1959 and the bridge floodlit during its centenary year. Over

3740-473: The bridge as a memorial. During the 20th century the approach spans were replaced, and the main spans strengthened. It has attracted sightseers since its construction and has appeared in many paintings, photographs, guidebooks, postage stamps and on the UK £2 coin. Anniversary celebrations took place in 1959 and 2009. Two rival schemes for a railway to Falmouth, Cornwall , were proposed in the 1830s. The 'central' scheme

3825-437: The bridge to Poland. Bridges can be categorized in several different ways. Common categories include the type of structural elements used, by what they carry, whether they are fixed or movable, and by the materials used. Bridges may be classified by how the actions of tension , compression , bending , torsion and shear are distributed through their structure. Most bridges will employ all of these to some degree, but only

3910-439: The bridge. Single track (rail) Single track is significantly cheaper to build and maintain, but has operational and safety disadvantages. For example, a single-track line that takes 15 minutes to travel through would have capacity for only two trains per hour in each direction safely. By contrast, a double track with signal boxes four minutes apart can allow up to 15 trains per hour in each direction safely, provided all

3995-439: The center of the bridge. Multi-way bridges with only three spans appear as a "T" or "Y" when viewed from above. Multi-way bridges are extremely rare. The Tridge , Margaret Bridge , and Zanesville Y-Bridge are examples. A bridge can be categorized by what it is designed to carry, such as trains, pedestrian or road traffic ( road bridge ), a pipeline ( Pipe bridge ) or waterway for water transport or barge traffic. An aqueduct

4080-467: The deck is thinner in proportion to its span, the lines of the structure are continuous, and the shapes of the structural elements reflect the forces acting on them. To create a beautiful image, some bridges are built much taller than necessary. This type, often found in east-Asian style gardens, is called a Moon bridge , evoking a rising full moon. Other garden bridges may cross only a dry bed of stream-washed pebbles, intended only to convey an impression of

4165-459: The decking were added in 1969 to further strengthen the bridge. In 2011 Network Rail began a three-year £10 million refurbishment involving replacing 50,000 bolts and installation of 100 tonnes of new steelwork. The bridge has also been stripped back to the bare metal and repainted in the Goose Grey colour originally applied in 1952. The construction of such a large and distinctive bridge soon caught

4250-702: The design Stephenson employed for the High Level Bridge across the River Tyne in Newcastle Upon Tyne in 1849. Brunel was present when Stephenson raised the girders of his Britannia Bridge across the Menai Strait in the same year. From 1849 to 1853 Brunel was erecting an iron bridge of his own; the Chepstow Railway Bridge carried the South Wales Railway across the River Wye and featured

4335-478: The early days of railways in North America it was common to rely upon simple timetable operation where operators knew where a train was scheduled to be at a particular time, and so would not enter a single-track stretch when they were not scheduled to. This generally worked but was inflexible and inefficient. It was improved with the invention of the telegraph and the ability to issue train orders . Converting

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4420-595: The first human-made bridges with significant span were probably intentionally felled trees. Among the oldest timber bridges is the Holzbrücke Rapperswil-Hurden bridge that crossed upper Lake Zürich in Switzerland; prehistoric timber pilings discovered to the west of the Seedamm causeway date back to 1523 BC. The first wooden footbridge there led across Lake Zürich; it was reconstructed several times through

4505-748: The late 1700s to the late 1800s, reminiscent of earlier designs in Germany and Switzerland. Some covered bridges were also built in Asia. In later years, some were partly made of stone or metal but the trusses were usually still made of wood; in the United States, there were three styles of trusses, the Queen Post, the Burr Arch and the Town Lattice. Hundreds of these structures still stand in North America. They were brought to

4590-464: The late 2nd century AD, when the Roman Empire built a 6-metre-wide (20 ft) wooden bridge to carry transport across the lake. Between 1358 and 1360, Rudolf IV, Duke of Austria , built a 'new' wooden bridge across the lake that was used until 1878; it was approximately 1,450 metres (4,760 ft) long and 4 metres (13 ft) wide. On 6 April 2001, a reconstruction of the original wooden footbridge

4675-427: The load is factored up by a factor greater than unity, while the resistance or capacity of the structure is factored down, by a factor less than unity. The effect of the factored load (stress, bending moment) should be less than the factored resistance to that effect. Both of these factors allow for uncertainty and are greater when the uncertainty is greater. Most bridges are utilitarian in appearance, but in some cases,

4760-514: The main Devon span. This was similarly floated into position on 10 July 1858 and then raised in a similar manner. It was in its final position by 28 December 1858. After this had been removed, part of the yard had to be cleared to allow the construction of the final landward pier and then the Devon approach spans could be raised up to their final position. The work was sufficiently advanced that directors were able to make an inspection by train on 11 April 1859. The Cornwall span had been tested before it

4845-614: The obstacle, which is usually something that is otherwise difficult or impossible to cross. There are many different designs of bridges, each serving a particular purpose and applicable to different situations. Designs of bridges vary depending on factors such as the function of the bridge, the nature of the terrain where the bridge is constructed and anchored, the material used to make it, and the funds available to build it. The earliest bridges were likely made with fallen trees and stepping stones . The Neolithic people built boardwalk bridges across marshland. The Arkadiko Bridge , dating from

4930-629: The past, these load models were agreed by standard drafting committees of experts but today, this situation is changing. It is now possible to measure the components of bridge traffic load, to weigh trucks, using weigh-in-motion (WIM) technologies. With extensive WIM databases, it is possible to calculate the maximum expected load effect in the specified return period. This is an active area of research, addressing issues of opposing direction lanes, side-by-side (same direction) lanes, traffic growth, permit/non-permit vehicles and long-span bridges (see below). Rather than repeat this complex process every time

5015-468: The principles of Load and Resistance Factor Design . Before factoring to allow for uncertainty, the load effect is generally considered to be the maximum characteristic value in a specified return period . Notably, in Europe, it is the maximum value expected in 1000 years. Bridge standards generally include a load model, deemed to represent the characteristic maximum load to be expected in the return period. In

5100-742: The roadways and reduced movement of the upper level when the lower level was installed three decades after the upper level. The Tsing Ma Bridge and Kap Shui Mun Bridge in Hong Kong have six lanes on their upper decks, and on their lower decks there are two lanes and a pair of tracks for MTR metro trains. Some double-decked bridges only use one level for street traffic; the Washington Avenue Bridge in Minneapolis reserves its lower level for automobile and light rail traffic and its upper level for pedestrian and bicycle traffic (predominantly students at

5185-698: The same year, has the span of 90 m (295 ft) and crosses the valley of the Syrabach River. The difference between the two is that the Solkan Bridge was built from stone blocks, whereas the Friedensbrücke was built from a mixture of crushed stone and cement mortar. The world's largest arch bridge is the Chaotianmen Bridge over the Yangtze River with a length of 1,741 m (5,712 ft) and

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5270-637: The simplest and oldest type of bridge in use today, and are a popular type. Some cantilever bridges also have a smaller beam connecting the two cantilevers, for extra strength. The largest cantilever bridge is the 549-metre (1,801 ft) Quebec Bridge in Quebec, Canada. With the span of 220 metres (720 ft), the Solkan Bridge over the Soča River at Solkan in Slovenia is the second-largest stone bridge in

5355-486: The subject of many photographs and postcards . It was already a feature in guidebooks in the year of its opening: "It is a labour of Hercules , but Mr Brunel has accomplished the feat," proclaimed one, and went on to report in detail the design and construction of the bridge that "for novelty and ingenuity of construction stands unrivalled in the world". More than 100 years later it continues to appear in many travel guides and features. John Betjeman summed up its impact on

5440-418: The suspended works for Brunel's Clifton Suspension Bridge and others rolled new for Saltash. The Cornwall span was floated into position on 1 September 1857 and jacked up to full height in 3-foot (0.9 m) stages as the piers were built up beneath it, the central pier using cast iron octagonal columns; the landward one using ordinary masonry. With the yard now cleared of the first truss, work could start on

5525-790: The time of the Warring States period , the oldest surviving stone bridge in China is the Zhaozhou Bridge , built from 595 to 605 AD during the Sui dynasty . This bridge is also historically significant as it is the world's oldest open-spandrel stone segmental arch bridge. European segmental arch bridges date back to at least the Alconétar Bridge (approximately 2nd century AD), while the enormous Roman era Trajan's Bridge (105 AD) featured open-spandrel segmental arches in wooden construction. Rope bridges ,

5610-584: The train driver had to be in possession of a token in order to enter a stretch of single track. Because there was only one unique token issued at any one time for each stretch of single track, it was impossible for more than one train to be on it at a time. This method is still used on some minor lines but in the longest single-track lines in Britain (e.g. the Highlands of Scotland) this has been superseded by radio communication, known as Radio Electronic Token Block . In

5695-424: The trains travel at the same speed. This hindrance on the capacity of a single track may be partly overcome by making the track one-way on alternate days. Long freight trains are a problem if the passing stretches are not long enough. Other disadvantages include the propagation of delays, since one delayed train on a single track will also delay any train waiting for it to pass. Also, a single track does not have

5780-488: The transition from Devon to Cornwall. In the Great Western Railway's The Cornish Riviera travel guide, SPB Mais regarded it as "an almost magic means of transporting travellers from a county, which, if richer than others, is yet unmistakingly an English county, to a Duchy which is in every respect un-English. You shut your eyes going over the Saltash Bridge only to open them again on a foreign scene". The bridge

5865-455: The traveller: The general grey slate and back gardens of Plymouth, as seen from the Great Western made the surprise of Saltash Bridge all the more exciting. Up and down stream, grey battleships were moored in the Tamar and its reaches. Hundreds of feet below, the pathetic steam ferry to Saltash from the Devon bank tried to compete with Brunel's mighty bridge. The bridge has become a symbol of

5950-412: The trusses to be supported with no horizontal thrust exerted on the piers, which is crucial in view of the curved track on either side. Between these two chords are supporting cross-bracing members and suspension standards which hang beneath the bottom chord to carry the railway deck which is a continuous plate beam. There are also 17 shorter and more conventional plate-girder approach spans on the shore. On

6035-740: The undertimbers of bridges all around the world are spots of prevalent graffiti. Some bridges attract people attempting suicide, and become known as suicide bridges . The materials used to build the structure are also used to categorize bridges. Until the end of the 18th century, bridges were made out of timber, stone and masonry. Modern bridges are currently built in concrete, steel, fiber reinforced polymers (FRP), stainless steel or combinations of those materials. Living bridges have been constructed of live plants such as Ficus elastica tree roots in India and wisteria vines in Japan. Unlike buildings whose design

6120-507: The variation of strength found in natural stone. One type of cement, called pozzolana , consisted of water, lime , sand, and volcanic rock . Brick and mortar bridges were built after the Roman era , as the technology for cement was lost (then later rediscovered). In India, the Arthashastra treatise by Kautilya mentions the construction of dams and bridges. A Mauryan bridge near Girnar

6205-404: The water higher upstream using a bridge at Saltash instead. The Act enabling this scheme was passed on 3 August 1846. The structure was the third in a series of three large wrought iron bridges built in the middle of the 19th century. It was influenced by the preceding two, both of which had been designed by Robert Stephenson . The two central sections of Brunel's bridge are novel adaptations of

6290-530: The water was pumped out, the mud within it excavated, and a solid masonry pier built up clear of the water. This was completed in November 1856. The landward piers on the Cornish side of the river were completed in 1854 and the girders for these spans were hoisted up to their correct positions. Next to be built was the main truss for the Cornwall side of the river. The lower ties of the trusses formed of chains made from 20 feet (6.1 m) links. Many were obtained from

6375-467: The water. This was rejected by the Admiralty , who had statutory responsibility for navigable waters, so Brunel produced a revised design to give 100 feet (30 m) clearance, with two spans of 300 feet (91 m) and two of 200 feet (61 m). The Admiralty again rejected this plan, stipulating that there should not be more than one pier in the navigable part of the river. Brunel now abandoned plans for

6460-453: The weekend of 21–22 May 1892 the track gauge on the bridge was converted from 7 ft  1 ⁄ 4  in ( 2,140 mm ) to 4 ft  8 + 1 ⁄ 2  in ( 1,435 mm ) during the final conversion of the whole Great Western Railway . 401 new cross-girders were fitted in 1905 to allow heavier locomotives to pass over. In 1908 the two spans nearest Saltash station were replaced with wider ones to accommodate

6545-433: The weld transitions . This results in a potential high benefit, using existing bridges far beyond the planned lifetime. While the response of a bridge to the applied loading is well understood, the applied traffic loading itself is still the subject of research. This is a statistical problem as loading is highly variable, particularly for road bridges. Load Effects in bridges (stresses, bending moments) are designed for using

6630-582: The word for the card game of the same name is unknown.   The simplest and earliest types of bridges were stepping stones . Neolithic people also built a form of boardwalk across marshes ; examples of such bridges include the Sweet Track and the Post Track in England, approximately 6000 years old. Ancient people would also have used log bridges consisting of logs that fell naturally or were intentionally felled or placed across streams. Some of

6715-448: The world and the longest railroad stone bridge. It was completed in 1905. Its arch, which was constructed from over 5,000 tonnes (4,900 long tons; 5,500 short tons) of stone blocks in just 18 days, is the second-largest stone arch in the world, surpassed only by the Friedensbrücke (Syratalviadukt) in Plauen , and the largest railroad stone arch. The arch of the Friedensbrücke, which was built in

6800-453: Was a route from Exeter around the north of Dartmoor , an easy route to construct but with little intermediate traffic. The other, the 'coastal' scheme, was a line with many engineering difficulties but which could serve the important naval town of Devonport and the industrial area around St Austell . The central scheme was backed by the London and South Western Railway while the coastal scheme

6885-562: Was approved by the Admiralty and the directors of the Cornwall Railway. The two spans are lenticular trusses with the top chord of each truss comprising a heavy tubular arch in compression, which tend to expand in length under load, while the bottom chord comprises a pair of chains, which tend to contract in length under load. By design, these two effects cancel so that there is no net change in length under load. This in turn enables each of

6970-402: Was launched. The two ends were supported on substantial timber piers and the remaining scaffolding removed. Static loads of 1.25 and 2.25 long tons per foot (4.2 and 7.5 t/m) were placed on the deck, the deflections measured and any permanent change measured once the load was removed. Now that it was completed, the bridge had its statutory inspection and tests by Colonel Yolland on behalf of

7055-519: Was opened; it is also the longest wooden bridge in Switzerland. The Arkadiko Bridge is one of four Mycenaean corbel arch bridges part of a former network of roads, designed to accommodate chariots , between the fort of Tiryns and town of Epidauros in the Peloponnese , in southern Greece . Dating to the Greek Bronze Age (13th century BC), it is one of the oldest arch bridges still in existence and use. Several intact, arched stone bridges from

7140-754: Was promoted by the Cornwall Railway and backed by the Great Western Railway which wanted it to join up with the South Devon Railway at Devonport . The Cornwall Railway applied for an Act of Parliament in 1845 but it was rejected, in part because of William Moorsom 's plan to carry trains across the water of the Hamoaze on the Devonport-to-Torpoint Ferry . Following this Isambard Kingdom Brunel took over as engineer and proposed to cross

7225-510: Was surveyed by James Princep . The bridge was swept away during a flood, and later repaired by Puspagupta, the chief architect of emperor Chandragupta I . The use of stronger bridges using plaited bamboo and iron chain was visible in India by about the 4th century. A number of bridges, both for military and commercial purposes, were constructed by the Mughal administration in India. Although large bridges of wooden construction existed in China at

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