Bridge


Pedestrian bridge over the River Windrush at Bourton-on-the-Water (south west England)

A bridge is an engineered structure built to span a gorge, valley, road, railroad track, river or other body of water, or any other physical obstacle.

Table of contents
1 History
2 Etymology
3 Types of bridge
4 Works of art
5 See also
6 Other meanings

History

The first bridges were simple wooden logs or planks spanning a stream or such; the next examples found use stone, but again as a simple support and crossbeam arrangement. The arch was first used by the Roman Empire for bridges, and many Roman bridges and aqueducts still exist today. The Romans also had 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.

With the advent of the Industrial Revolution of 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, with its high tensile strength, much larger bridges were built, many using the ideas of Gustave Eiffel, which were first shown at the Eiffel Tower in Paris France.


Clifton Suspension Bridge spanning the River Avon in Bristol, England

Etymology

The Oxford English Dictionary traces the origin of the word bridge to an Old Norse word brygga, meaning "landing stage, gangway, or movable pier".

Types of bridge

A bridge is usually either designed for trains, pedestrian or road traffic. In the latter case 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. A bridge which has a series of spans, typically arches, is called a viaduct. An aqueduct is a kind of bridge that carries water, resembling a viaduct. Sometimes a bridge carries a pipeline only. When a bridge spans a road or railroad track, it is often called an overpass (US) or flyover (UK).

Movable bridges

To allow ships to pass which can not pass under it, a bridge may be constructed such that it (or part of it) can be turned up (drawbridge; either one part or two) or sideways (swing bridge). A third method is that the bridge deck is lifted while staying horizontal (lift bridge or lifting bridge). (Alternatively, if road traffic is very light, a transporter bridge may be used.)

For small bridges these movements may be enabled without the need for an engine. Some bridges are operated by the users, especially those with a boat, others by a bridge-man/woman, sometimes remotely using video-cameras and loudspeakers.

There are often traffic lights for the road and water traffic, and moving barriers for the road traffic.

See also

Works of art

featuring bridges or using a bridge metaphor

See also

Other meanings

The bridge of a ship is so called because it once was a bridge between paddlewheels on either side of early steamboats. This new vantage point was deemed so convenient that it was retained after the paddlewheels were superseded.

Bridge is also the name of a card game, short for "contract bridge" or "auction bridge" or "duplicate bridge."
In a musical string instrument a bridge is the device which anchors the strings at the body end of the strings.
In song writing a bridge is a part of a song that connects two parts of that song, building a harmonic connection between those parts.
A bridge, or "partial plate," is a dental prosthesis used in place of missing teeth and may be removable or permanently attached.
A bridge is an electronic device used to connect two segments of a computer network (combining two networks) or of a telephone network (to support multi-party conference call on telephone).
A bridge, short for "bridge loan," is the financing for a construction project that is replaced by (= paid off with the proceeds of) a mortgage on the property once it is built.
In computer science Bridge is the name of a design pattern for computer programming introduced by the Gang of Four in their book Design Patterns. Its use is to separate an abstraction and its actual implementation into separate class hierarchies.


In the News

Using Computerized Sense Of Touch Over Long Distances: Haptics For Ind
Firstly, what is "Haptics"? This term means "of or relating to the sense of touch."Haptic technology, or haptics, refers to the technology that connects the user to a computerized system via the sense of touch by applying forces, vibrations and/or motions to the user.

Primate Embryonic Stem Cells Successfully Cloned
Researchers at Oregon Health &Science University's Oregon National Primate Research Center have made a significant breakthrough in efforts to develop human stem cell therapies that may be used to combat numerous devastating diseases. For the first time, scientists have successfully derived embryonic stem cells by reprogramming of genetic material from skin cells while studying rhesus macaque monkeys. The breakthrough follows several previously unsuccessful attempts by the OHSU-based team and other scientific teams worldwide.

Crime Prevention Month
Collection of tips and publications for Crime Prevention Month, observed annually in October. "The month-long celebration spotlights successful crime prevention efforts on the local, state, and national levels."Includes Halloween safety brochures and links to other crime prevention material. From the National Crime Prevention Council.

Why We Love Oil
A handy graphic levels the energy playing field and puts our petroleum infatuation in perspective. In Wired Science.

Dying Speeches &Bloody Murder: Crime Broadsides Collected by the Harva
"Just as programs are sold at sporting events today, broadsides -- styled at the time as 'Last Dying Speeches' or 'Bloody Murders' -- were sold to the audiences that gathered to witness public executions in eighteenth- and nineteenth-century Britain. ... The examples digitized here span the years 1707 to 1891 and include accounts of executions for such crimes as arson, assault, counterfeiting, horse stealing, murder, rape, robbery, and treason."From the Harvard Law School Library.

Aircraft Captures Windy Details In Hurricane's Ups And Downs
Researchers employing some of the world's most sophisticated weather research equipment recently captured details on winds and other conditions in a rapidly intensifying hurricane. This data will help to advance the understanding of these complex storms. Presentation (A13E-0994, Poster) at the American Geophysical Union meeting, December 11, 4:40 p.m. EST.

EFF: Legal Guide for Bloggers
The goal of this site is to give users "a basic roadmap to the legal issues you may confront as a blogger, [and] to let you know you have rights."Includes FAQs on intellectual property, online defamation law, section 230 (of the Communication Decency Act of 1996) protections, and privacy; FAQs for bloggers as journalists (reporter's privilege and media access); and FAQs relating to election and labor laws. From the Electronic Frontier Foundation (EFF).

Attack of the Bots
Autonomous programs that combine forces to perpetrate mayhem, fraud and espionage pose the latest threat to the net. Here's how one company fought the new internet mafia -- and lost. By Scott Berinato from Wired magazine.

WPA: Sin Nombre: Hispana and Hispano Artists of the New Deal Era
"Hundreds of Hispana and Hispano artists created art for the various New Deal programs during the 1930s and 1940s under the presidency of Franklin Delano Roosevelt. 'Sin Nombre' (Without Name) presents the work of these artists."The site features an overview of Works Progress Administration (WPA) programs in New Mexico and information about and images of work from selected artists. Also includes videos. Searchable. In English and Spanish. From the Museum of International Folk Art.

Changes In Amino Acids In 1918 Influenza Virus Cut Transmission
Modest changes in the 1918 flu virus's hemagglutinin receptor binding site -- a molecular structure critical for the spread of infection -- stopped viral transmission in ferrets, according to a new study conducted by researchers at Mount Sinai School of Medicine and at the Centers for Disease Control and Prevention. The finding, published in the February 1 issue of Science, could have significant clinical implications in helping scientists develop ways to break the disease cycle and possibly help reduce the risk for a potential pandemic.


MP3 Music Downloads

Preview songs, Download Free Music,Burn CDs at ITunes.com
iTunes_RGB_9mm

 

Google




InformationQuickFind.com - Find Information Fast

Links