Learn more about Bridge
A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. Designs may be built higher than otherwise needed in order to allow other traffic (particularly ship traffic) beneath.
The purpose of a bridge is to allow people or cargo easy passage over an obstacle by providing a route that would otherwise be uneven or impossible.
The arch was first used by the Roman Empire for bridges and aqueducts, some of which still stand today. The Romans also used cement, which reduced the variation of strength found in natural stone. Brick and mortar bridges were built after the Roman era, as the technology for cement was lost then later rediscovered.
During the 18th century there were many innovations in the design of timber bridges by Hans Ulrich, Johannes Grubenmann, and others. The first engineering book on building bridges was written by Hubert Gautier in 1716.
With the Industrial Revolution in the 19th century, truss systems of wrought iron were developed for larger bridges, but iron did 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.
The Oxford English Dictionary traces the origin of the word bridge to an Old English word brycg, of the same meaning, derived from a hypothetical Proto-Germanic root brugjō. There are cognates in other Germanic languages (for instance Brücke in German, brug in Dutch or bro in Danish and Swedish).
The word for the Pope, pontiff, comes from the Latin word pontifex meaning "bridge builder".
 Types of bridges
 By use
A bridge is designed for trains, pedestrian or road traffic, a pipeline or waterway for water transport or barge traffic. In some cases there may be restrictions in use. For example, it may be a bridge carrying a highway and forbidden for pedestrians and bicycles, or a pedestrian bridge, possibly also for bicycles.
 Decorative and ceremonial bridges
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 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, the People's Republic of China. The central bridge was reserved exclusively for the use of the Emperor, Empress, and their attendants.
 Index to types of bridges
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 Index to bridge related topics
 Bridge structural and evolutionary taxonomy
Bridges may be classified by how the four forces of tension, compression, bending and shear are distributed through their structure. Most bridges will employ all of the principle forces to some degree, but only a few will predominate. The separation of forces may be quite clear. In a suspension or cable-stayed span, 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, or not clearly discernible to a casual observer as in a box beam. Bridges can also be classified by their lineage, which is shown as the vertical axis on the diagram to the right.
A bridge's structural efficiency may be considered to be the ratio of load carried to bridge weight, given a specific set of material types. In one common challenge students are divided into groups and given a quantity of wood sticks, a distance to span, and glue, and then asked to construct a bridge that will be tested to destruction by the progressive addition of load at the center of the span. The bridge taking the greatest load is by this test the most structurally efficient. A more refined measure for this exercise is to weigh the completed bridge rather than measure against a fixed quantity of materials provided and determine the multiple of this weight that the bridge can carry, a test that emphasizes economy of materials and efficient glue joints (see balsa wood bridge).
A bridge's economic efficiency will be site and traffic dependent, the ratio of savings by having a bridge (instead of, for example, a ferry, or a longer road route) compared to its cost. The lifetime cost is composed of materials, labor, machinery, engineering, cost of money, insurance, maintenance, refurbishment, and ultimately, demolition and associated disposal, recycling, and reuse. Bridges employing only compression are relatively inefficient structurally, but may be highly cost efficient where suitable materials are available near the site and the cost of labor is low. For medium spans, trusses or box beams are usually most economical, while in some cases, the appearance of the bridge may be more important than its cost efficiency. The longest spans usually require suspension bridges.
 Notable bridges
- Albert Edward Bridge - England, large single span cast iron railway bridge similar to Victoria Bridge
- Akashi-Kaikyo Bridge - Japan, suspension bridge with the longest section span of 1.9 km.
- Bosphorus Bridge - Turkey, connects Asia and Europe
- Brooklyn Bridge - connecting the New York City boroughs of Manhattan and Brooklyn.
- Charles Bridge - Czech Republic, famous 14th century bridge in Prague
- Chicago Skyway - USA, a 7.8-mile toll bridge bypassing much of the southwest of Chicago
- Confederation Bridge - Canada, world's longest bridge over waters that freeze.
- Forth Railway Bridge - Scotland, one of the most famous cantilever bridges in the world.
- Golden Gate Bridge - USA, one of the most famous suspension bridges in the world.
- Great Belt Fixed Link, Eastern Bridge - Denmark, second longest section span of 1.6 km
- Hangzhou Bay Bridge - under construction, scheduled to be completed in 2008. A cable-stayed bridge across Hangzhou Bay, China. It will be the second-longest bridge in the world and the longest trans-oceanic bridge
- Hercilio Luz Bridge - Florianopolis, Brazil, longest Brazilian suspension bridge, one of the 100 largest suspension bridges of the world and one of the oldest hanging bridges in the world.
- The Iron Bridge - England, the world's first iron bridge.
- Jamuna Bridge- Bangladesh, longest rail-road bridge in south asia , 2nd longest in world.
- Lake Pontchartrain Causeway - USA, spanning Lake Pontchartrain in south Louisiana, it is the longest bridge in the world at 23.87 miles (38.41 km).
- Lupu Bridge- the People's Republic of China, longest single steel arch.
- Mackinac Bridge - USA, Opened to traffic in 1957, connecting the two peninsulas of Michigan; held the title of the world's longest two tower suspension bridge between anchorages until the 1990s.
- Mahatma Gandhi Setu - India, the longest river bridge in the world.
- Menai Suspension Bridge - Wales, first road suspension bridge in the world.
- Millau Viaduct - France, the tallest vehicular bridge in the world.
- Natchez Trace Parkway Bridge - USA, a rare example of a segmented precast concrete arch bridge, and the first to be built in the US.
- Øresundbroen/Öresundsbron - Denmark - Sweden - Built year 2000. Connects Sweden with Denmark and Northern Europe with Europe
- Overtoun Bridge, - Scotland, dogs have leaped to their deaths from this bridge, leading to urban legends.
- Palace Bridge - St Petersburg, Russia, one of iconic images of the city
- Penang Bridge - Malaysia, longest bridge in Southeast Asia.
- Penobscot Narrows Bridge - USA, first bridge in the Western Hemisphere with an observatory<ref>
Brian MacQuarrie. "View from a bridge", The Boston Globe, October 8, 2006. Retrieved on 2006-10-08.</ref>,first bridge to use a nitrogen gas enclosed around each cable stay<ref> Tanya Mitchell. "Just the facts", VillageSoup, September 28, 2006. Retrieved on 2006-10-08.</ref>.
- Québec Bridge - Canada, largest cantilever bridge in the world.
- Rio-Antirio bridge - Greece, the longest cable-stayed bridge in the world.
- Rio-Niterói Bridge - Brazil, highest central span in the world.
- San Francisco-Oakland Bay Bridge - USA, especially for seismic retrofit and eastern span replacement.
- Sundial Bridge - USA, a dramatic single cantilever spar cable stayed span for pedestrians.
- Sunshine Skyway Bridge - USA, longest cable-stayed concrete bridge in the world. Replaced a cantilever truss structure which partially collapsed in 1980 as a result of collision by a freighter.
- Sydney Harbour Bridge - Australia, arguably the best-known suspended-deck compression arch bridge, also the world's widest long span bridge (according to Guinness World Records).
- Tacoma Narrows Bridge - USA, famous for its collapse due to aerodynamic effects.
- Tatara Bridge - Japan, largest span cable-stayed bridge.
- Tower Bridge - London, England, and a symbol of this city.
- Trajan's bridge - Romania, ancient Roman bridge over the river Danube, only fragments visible.
- Tsing Ma Bridge - Hong Kong, the world's longest rail & road suspension bridge
- Tyne Bridge - England, one of Northern England's most iconic structures.
- Vasco da Gama Bridge - Portugal, the longest bridge in Europe at 17.2 km.
- Verrazano-Narrows Bridge - USA - longest suspension bridge in USA.
- Victoria Bridge - England large single span cast iron railway bridge similar to Albert Edward Bridge
- Victoria Falls Bridge - linking Zimbabwe to Zambia, built in 1905 as part of the projected Cape-Cairo railway.
- Zakim Bunker Hill Bridge - USA, built during Boston's Big Dig, the widest cable-stayed bridge.
 Special Installations
A bridge can carry overhead powerlines as the Storstrøm Bridge.
 Catastrophic collapses
|Bridge||Town||Country||Date||Construction type, use of bridge||Reason||Number death/injuries||Damage||Remarks|
|Stirling Bridge||Stirling||Scotland||September 1297||Beam and trestle over the River Forth||Overload by attackers during the Battle of Stirling Bridge||Unknown, attacking forces defeated||Bridge rendered unusable||Collapse may have been assisted by defending forces.|
|Bridge of Angers (France)||Angers||France||April 16 1850||Suspension bridge over Maine River||Resonance of soldiers led to collapse||226/?||Bridge total damage||Marching columns now break step when crossing bridges.|
|Yarmouth Bridge||Great Yarmouth||England||May 2 1845||Suspension||People had crowded onto the bridge to see a circus clown go down the river in a barrel pulled by geese. The weight of people shifted as the barrel passed underneath, the suspension chains on the south side snapped and the bridge deck tipped over.||79 people drowned, mainly children.||Suspension chains snapped due to overload.|||
|Tay Rail Bridge||Dundee||Scotland||December 28 1879||Continuous girder bridge, steel framework on cast iron columns, railway bridge||Insufficient consideration of the wind load, inadequate construction, collapsed because of the stresses caused by a storm||75/0||Bridge unusable, piers partly reused, train heavily damaged||Locomotive was saved from the Tay and was still in use 19 years later known as "The Diver".|
|Québec Bridge||Quebec||Canada||August 29 1907||Cantilever bridge, steel framework, railway bridge||Collapsed during construction||74/11||Bridge completely destroyed|
|Theodor-Heuss-Rhine River Bridge||Ludwigshafen||Germany||March 1940||Bridge of concrete, Motorway bridge||Collapsed during construction||?/?||Bridge totally destroyed||Resulted in delay in completion of the motorway crossing of the Rhine until 1953|
|Tacoma Narrows Bridge||Tacoma, WA||USA||November 7 1940||Road bridge, cable suspension with plate girder deck||Aerodynamically poor form resulted in resonance||No||Bridge partially destroyed, one car lost, and one dog killed||Became known as "Galloping Gertie", in the first 4 months after opening up until its collapse under a previously unseen resonant mode. Since that time all new bridges have been modelled in wind tunnels.|
|The bridge at Remagen||Remagen||Germany||March 17 1945||Truss railroad and pedestrian bridge||Collapse due to previous battle damage incurred March 7th, 1945||28 U.S. soldiers||Total destruction||Capture of intact bridge offered significant short term tactical advantage to Allied forces. Collapse was not strategically significant due to placement of parallel floating bridges during the previous week|
|Harrow and Wealdstone rail crash||Wealdstone||England||October 8 1952||Pedestrian footbridge||Struck by train(s) during accident||112 dead 340 injured||Total destruction||It is not recorded how many casualties were due to the bridge collapse|
|Tangiwai railway bridge||Tangiwai||New Zealand||December 24 1953||Railway bridge||Damaged by lahar minutes before passenger train passed over it.||134/151||Bridge destroyed|
|General Rafael Urdaneta Bridge||Maracaibo||Venezuela||April 6 1964||Road bridge||Ship collision||7||2 section collapsed||Currently in Operation|
|Silver Bridge||USA||15 December 1967||Road bridge, chain link suspension||Material fault and Corrosion||46/9||Bridge and 37 vehicles destroyed|
|West Gate Bridge||Melbourne||Australia||October 15, 1970||Road Bridge||Collapse during construction||35||112 metre span between piers 10 and 11 collapsed||Section sprung back and collapse during attempts to remove a buckle cause by a difference in camber of 4.5 inches|
|South Bridge Koblenz||Koblenz||Germany||10 November 1971||Road bridge||Bridge bent into Rhine||13/?||Bridge completely destroyed|
|Reichsbrücke||Vienna||Austria||August 1, 1976||Road bridge with Tram||Column fractured||1/0||Bridge, one bus and a lorry destroyed, ships damaged||Concrete of the column had never been examined, was internally totally destroyed; "higher force"|
|Tasman Bridge||Hobart||Tasmania, Australia||January 5, 1975||Bridge of concrete, Motorway bridge||Ore freighter Lake Illawarra collided with pylons. Section of bridge collapsed onto frieghter. Four cars fell into the river.||7 ship crewman and 5 motorists killed||2 pylons and three sections of bridge collapsed, ore freighter sank, 5 cars fell into river||City of Hobart was split in two. Residents living in the east were forced to make a 50km trip to the CBD via the next bridge up north. Bridge was reconstructed and reopened on October 8, 1977|
|Almö Bridge||Stenungsund||Sweden||January 18, 1980||Bridge with bow built of concrete||Ship collision||8/?||Bridge and several cars destroyed|
|Sunshine Skyway Bridge||USA||1980||Steel Cantilever Bridge||Ship collision||35/?||1200 ft. of southbound span, several cars and a bus destroyed||Demolished and replaced with cable-stayed bridge|
|Aschaffenburg Main River Freeway Bridge||Aschaffenburg||Germany||1988||Bridge of Motorway A 3 over River Main||Error in construction||1/0||Bridge total damage||Partial collapse at Repetitive sliding|
|Bridge over railway line at Eschede||Eschede||Germany||June 3, 1998||Road bridge||Train disaster||101/105||Destruction by train crashing on pillar, killed and injured people were train passengers|
|Loncomilla Bridge||near San Javier||Chile||November 18, 2004||Concrete bridge for vehicle traffice over Maule River||The structure was not build on rock, but rather on fluvial ground.||0/8||Partial collapse||Bridge was later repaired|
|Motorway bridge at Almuñecar, Province of Granada, Spain (search correct name of bridge)||Almuñecar||Spain||November 7 2005||Motorway bridge||Construction, accident, reason unknown||6/3||A 60 metre long part fell 50 metre deep|
|Viaducto No.1 Caracas - La Guaira motorway Tacagua, Venezuela||Tacagua||Venezuela||January 8 2006||Motorway bridge||Various factors||0/0||Bridge rendered unusable||Demolished, it will be replaced with a new one|
 See also
|Wikimedia Commons has media related to:|
- Landscape architecture
- Architectural structure
- BASE jumping
- List of bridges
- List of bridges by length
- List of largest suspension bridges
- Moveable bridge
- List of bridge disasters
 External links
- Structurae - International Database and Gallery of Structures with over 10 000 Bridges.
- American Society of Landscape Architects Designing Bridges in Landscape Architecture - The Bridge Architect
- American Society of Civil Engineers History and Heritage of Civil Engineering - Bridges
- Bridge Building — Art and Science Comprehensive explanations about bridges.
- Bridge Basics A guide to bridge terminology and styles
- Bridge disasters
- A dictionary of bridge terms
- Digital Bridge Library at Lehigh University
- Flickr Pictures tagged with Bridge by most interesting
- Bridges and Tunnels of Allegheny County and Pittsburgh, PA Details of over 2,000 bridges of 8 feet span or greater. Bridge engineers hold their conventions in Pittsburgh.
- Federal Highway Administration Bridge Technology
- Video on how bridges are made (Grade school level educational film by National Association of Manufactures.) Caution: Other links on this page may lead to politically biased material.
- Federal Highway Administration - The Landscape Architect's Role as Designer of Roads and Bridgesar:جسر
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