It was originally usual for passengers to cross from one railway platform to another by stepping over the tracks, but from the midth century onwards safety demanded the provision of a footbridge or underpass at busier places. However, in some quieter areas, crossing the line by walking over the tracks is possible. Narrow footbridges or walkways to allow workers access to parts of a structure otherwise difficult to reach are referred as catwalks or cat walks.
The walkway on the outside top of a railroad cars such as boxcars , before air brakes came into use, or on top of some covered hopper cars is also called a catwalk. Since the early s, several charities have developed standardized footbridge designs that are sustainable for use in developing countries. The first charity to develop such designs was Helvetas, located in Zurich, Switzerland. The Walkway Over The Hudson footbridge was originally built for trains, it was recently restored as a pedestrian walkway.
The footbridge has a total length of 2, meters 6, feet. Before it was demolished in , the Hornibrook Bridge which crossed Bramble Bay in Queensland , Australia was longer than the Poughkeepsie Bridge at 2. Much rural travel takes place on local footpaths , tracks and village roads.
These provide essential access to water, firewood, farm plots and the classified road network.
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Pedestrian overpasses over highways or railroads are expensive, especially when elevators or long ramps for wheelchair users are required. Without elevators or ramps, people with mobility handicaps will not be able to use the structure. People may prefer to walk across a busy road rather than climb a bridge. It is recommended that overpasses should only be used where the number of users justify the costs.
Narrow, enclosed structures can result in perceptions of low personal security among users. Wider structures and good lighting can help reduce this. Boardwalk across the High Fens , Ardenne , Belgium. A stressed ribbon bridge for pedestrians, bicycles, and pipelines in Grants Pass, Oregon. Melbourne's Sandridge Bridge which overpasses the Yarra River. The Puente de la Mujer in Puerto Madero is a footbridge and swing bridge.
the walkway to the footbridge - Picture of Dubai Water Canal, Dubai
A pedestrian overcross in Nanjing Road , Shanghai. A footbridge with four elevators on each corner of a four-way intersection in Tokyo. From Wikipedia, the free encyclopedia. Tamchog Chakzam bridge, Bhutan. A footbridge over a canal in Venice. Wooden footbridge in Vang Vieng , Laos. The "Ypsilon" Y-bridge in Drammen , Norway.
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Rope bridges , 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. During the 18th century there were many innovations in the design of timber bridges by Hans Ulrich Grubenmann , Johannes Grubenmann , and others.
The first book on bridge engineering was written by Hubert Gautier in A major breakthrough in bridge technology came with the erection of the Iron Bridge in Shropshire, England in It used cast iron for the first time as arches to cross 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 U. Some covered bridges were also built in Asia. They were brought to the attention of the general public in the s by the novel, movie, and play The Bridges of Madison County. Before humans, ants have been making bridges using their own bodies to allow others to cross.
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 forces of tension , compression , bending , torsion and shear are distributed through their structure.
Most bridges will employ all of the principal 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.
Some cantilever bridges also have a smaller beam connecting the two cantilevers, for extra strength. It was completed in The bridge was opened April 29, in Chongqing , China.
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The longest cable-stayed bridge since is the Russky Bridge in Vladivostok , Russia. 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, and taken apart, transported to 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.
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 million vehicles annually; [32] [33] truss work between the roadway levels provided stiffness to the roadways and reduced movement of the upper level when the lower level was installed three decades after the upper level.
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 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.
Robert Stephenson 's High Level Bridge across the River Tyne in Newcastle upon Tyne , completed in , is an early example of a double-decked bridge. The upper level carries a railway, and the lower level is used for road traffic. Tower Bridge in London 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 three-way bridge has three separate spans which meet near the center of the bridge. The bridge appears as a "T" or "Y" when viewed from above. Three-way bridges are extremely rare. A bridge can be categorized by what it is designed to carry, such as trains, pedestrian or road traffic road bridge , a pipeline or waterway for water transport or barge traffic.
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An aqueduct 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.
Other suspension bridge towers carry transmission antennas. Bridges are subject to unplanned uses as well. The areas underneath some bridges have become makeshift shelters and homes to homeless people, and 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 [35] and wisteria vines in Japan. Most bridges are utilitarian in appearance, but in some cases, 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 to aesthetics, as well. 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 , China. The central bridge was reserved exclusively for the use of the Emperor, Empress, and their attendants. Bridge maintenance consisting of a combination of structural health monitoring and testing. This is regulated in country-specific engineer standards and includes e. In Europe, the cost of maintenance is higher than spending on new bridges.
The lifetime of welded steel bridges can be significantly extended by aftertreatment of the weld transitions. This results in a potential high benefit, using existing bridges far beyond the planned lifetime. The failure of bridges is of special concern for structural engineers in trying to learn lessons vital to bridge design, construction and maintenance. Trump realDonaldTrump March 15, To keep the disruption of traffic to a minimum, a foot portion of the bridge was built adjacent to the street and was driven into its perpendicular position across the road by a rig in only six hours on Saturday, according to the university.
The bridge was the first in the world to be constructed entirely of self-cleaning concrete, according to the university. Titanium dioxide used in its construction, when exposed to sunlight, captures air pollutants and keeps the surface white.
The footbridge was designed to withstand a Category 5 hurricane, the most dangerous measure by the National Hurricane Center, and last years, according to the university. According to local media, the pedestrian bridge was constructed as a person was killed on the Miami-Dade highway. Munilla Construction Management, the company that constructed the footbridge, said in the statement saying their "thoughts and prayers go out to everyone affected by this terrible tragedy.