A bridge is a structure built to span a gorge, valley, road, railroad track, river, body of water, or any other physical obstacle. Designs of bridges will vary depending on the function of the bridge and the nature of the terrain where the bridge is to be constructed.
The first bridges were spans made of wooden logs or planks and eventually stones, using a simple support and crossbeam arrangement. Most of these early bridges were very poorly built and could rarely support heavy weights. It was this inadequacy which led to the development of better bridges. The arch was first used by the Roman Empire for bridges and aqueducts, some of which still stand today. These arch based bridges could stand in conditions that would damage or destroy more primitive designs.
An example is the Alcántara Bridge, built over the river Tagus, near Portugal. Most earlier bridges would have been swept away by the strong current. The Romans also used cement, which lowered the variation of strength found in natural stone. One kind of cement, called pozzolana, was made of water, lime, sand, and volcanic rock. Brick and mortar bridges were built after the Roman era, because the technology for concrete was lost and then later rediscovered.
Although large Chinese bridges existed in wooden construction since the ancient Warring States, 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.
The New River Gorge Bridge in Fayetteville, West Virginia is a steel arch bridge that opened in 1977 and is 3030 ft (924 m) long and 876 ft (267 m) high.
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The BP Pedestrian Bridge, or simply BP Bridge, is a girder footbridge in the Loop community area of Chicago, Illinois, United States. It spans Columbus Drive to connect Daley Bicentennial Plaza with Millennium Park, both parts of the larger Grant Park. Designed by Pritzker Prize-winning architect Frank Gehry, it opened along with the rest of Millennium Park on July 16, 2004. Gehry had been courted by the city to design the bridge and the neighboring Jay Pritzker Pavilion, and eventually agreed to do so after the Pritzker family funded the Pavilion. Named for energy firm BP, which donated $5 million toward its construction, it is the first Gehry-designed bridge to have been completed. BP Bridge is described as snakelike because of its curving form. Designed to bear a heavy load without structural problems caused by its own weight, it has won awards for its use of sheet metal. The bridge is known for its aesthetics, and Gehry's style is seen in its biomorphic allusions and extensive sculptural use of stainless steel plates to express abstraction.
The pedestrian bridge serves as a noise barrier for traffic sounds from Columbus Drive. It is a connecting link between Millennium Park and destinations to the east, such as the nearby lakefront, other parts of Grant Park and a parking garage. BP Bridge uses a concealed box girder design with a concrete base, and its deck is covered by hardwood floor boards. It is designed without handrails, using stainless steel parapets instead. The total length is 935 feet (285 m), with a five percent slope on its inclined surfaces that makes it barrier free and accessible. Although the bridge is closed in winter because ice cannot be safely removed from its wooden walkway, it has received favorable reviews for its design and aesthetics.
Kaichi Watanabe was a Japanese engineer who studied and worked in Scotland, United Kingdom during the 1880s. He was one of the first Japanese engineers who came to study in the UK. He is best known for his work with Sir John Fowler and Sir Benjamin Baker in cantilever bridge construction, notably on the Forth Rail Bridge.
Watanabe studied under Henry Dyer, the Scottish engineer associated with technical education in Japan. After obtaining a degree from the Faculty of Technology of the University of Tokyo, he studied at the University of Glasgow from 1885 and graduated with a Civil Engineering and Bachelor of Science degree, and worked as a construction foreman on the Forth Rail Bridge, which crossed the Firth of Forth in eastern Scotland in 1890.
Watanabe's image became well-known in the 1887 photograph illustrating the cantilever principle, in which he poses with Fowler and Baker, suspended between the engineers who form a cantilever structure with their arms.
Bridge types: Arch bridge, Aqueduct, Bailey bridge, Bascule bridge, Beam bridge, Box girder bridge, Cable-stayed bridge, Caisson, Cantilever bridge, Cantilever spar cable-stayed bridge, Clapper bridge, Covered bridge, Curling bridge, Drawbridge, Extradosed bridge, Folding bridge, Footbridge, Girder bridge, Inca rope bridge, Jetway, Lattice truss bridge, Log bridge, Mabey Logistic Support Bridge, Moon bridge, Plate girder bridge, Pontoon bridge, Retractable bridge, Self-anchored suspension bridge, Segmental bridge, Side-spar cable-stayed bridge, Simple suspension bridge, Skew arch bridge, Step-stone bridge, Stressed ribbon bridge, Submersible bridge, Suspension bridge, Swing bridge, Tied arch bridge, Tilt bridge, Through arch bridge, Toll bridge, Transporter bridge, Trestle, Truss arch bridge, Truss bridge, Tubular bridge, Vertical lift bridge, Viaduct, Vierendeel bridge, Weigh bridge, Zig-zag bridge
Individual bridges Contoocook Railroad Bridge, Akashi Kaikyo Bridge, Delaware Memorial Bridge, Forth Bridge, Golden Gate Bridge, Huey P. Long Bridge, Humber Bridge, Kintai Bridge, Lake Ponchartrain Causeway, Mike O'Callaghan - Pat Tillman Memorial Bridge, Millau Viaduct, New River Gorge Bridge, Pont de Normandie, Rion-Antirion Bridge, San Francisco - Oakland Bay Bridge (Eastern span replacement), San Mateo – Hayward Bridge, Stonecutters Bridge, Sunshine Skyway Bridge, Tacoma Narrows Bridge, Tsing Ma Bridge, Verrazano-Narrows Bridge(please expand)
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