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 Sydney Harbour Bridge in Australia, carries rail, vehicular, bicycle and pedestrian traffic between the Sydney CBD and the North Shore.
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The Pont du Gard is an ancient Roman aqueduct bridge that crosses the Gardon River in Vers-Pont-du-Gard near Remoulins, in the Gard département of southern France. It is part of the Nîmes aqueduct, a 50 km-long (31 mi) structure built by the Romans to carry water from a spring at Uzès to the Roman colony of Nemausus (Nîmes). Because the terrain between the two points is hilly, the aqueduct – built mostly underground – took a long, winding route that crossed the gorge of the Gardon, requiring the construction of an aqueduct bridge. Built in the 1st century AD, the Pont du Gard is the highest of all Roman aqueduct bridges and is the best preserved after the Aqueduct of Segovia. It was added to UNESCO's list of World Heritage Sites in 1985 because of its historical importance.
The bridge has three tiers of arches, standing 48.8 m (160 ft) high. The whole aqueduct descends in height by only 17 m (56 ft) over its entire length, while the bridge descends by a mere 2.5 cm (0.98 in) – a gradient of only 1 in 3,000 – which is indicative of the great precision that Roman engineers were able to achieve using only simple technology. The aqueduct formerly carried an estimated 200,000 m3 (44,000,000 imp gal) of water a day to the fountains, baths and homes of the citizens of Nîmes. It continued to be used possibly until the 6th century, with some parts used for significantly longer, but lack of maintenance after the 4th century meant that it became increasingly clogged by mineral deposits and debris that eventually choked off the flow of water.
Albert Fink (October 27, 1827 – April 3, 1897) was a German civil engineer. He is best known for his railroad bridge designs, and devising the Fink truss.
Born in Lauterbach, Hesse, Germany, he studied architecture and engineering at the Polytechnic school in Darmstadt, and graduated in 1848. In 1849 he emigrated to the United States. He soon found work with the Baltimore and Ohio Railroad as a draftsman, and became chief office assistant to Benjamin H. Latrobe. In this position he oversaw the design and construction of buildings and bridges. With the construction of the road between Cumberland, Maryland and Wheeling, West Virginia (then in the state of Virginia). Fink supervised much of the design, and oversaw the building of some of the first iron bridges in the nation, including that over the Monongahela River in Fairmont, West Virginia. It was this bridge that first implemented his design of the Fink truss, and was in fact in its time the longest iron railroad bridge. With the completion of this portion of road, the section between Grafton and Parkersburg, West Virginia was commenced, and many of the bridges and tunnels of this route were also supervised by him. He was also during this time a consulting engineer of the Norfolk and Petersburg railway, which was at the time building the bridge at Norfolk, Virginia. He left the Baltimore and Ohio railroad in 1857 to become the assistant of George McLeod, chief engineer of the Louisville and Nashville Railroad. Under them he built numerous bridges, including the Green River Bridge in Kentucky, then the longest iron bridge in the nation, a bridge in Nashville, Tennessee over the Cumberland, and one over the Ohio at Louisville, Kentucky, which at one mile in length was the longest truss bridge of its time.
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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