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 Dom Luís Bridge, Porto, a metal arch bridge that spans the Douro River between the cities of Porto and Vila Nova de Gaia in Portugal.
- Expand this portal.
- Select featured and good articles.
The Sonestown Covered Bridge is a Burr arch truss covered bridge over Muncy Creek in Davidson Township, Sullivan County, in the U.S. state of Pennsylvania. Built circa 1850, the bridge is 110 feet (34 m) long, and was placed on the National Register of Historic Places (NRHP) in 1980. The bridge is named for the nearby unincorporated village of Sonestown in Davidson Township, and is also known as the Davidson Covered Bridge. It was built to provide access to a gristmill, which operated until the early 20th century.
Pennsylvania had the first covered bridge in the United States and the most such bridges in the 19th, 20th, and 21st centuries. In most places in the state they were a transition between stone and metal bridges, with the roof and sides protecting the wooden structure from weather. The Sonestown bridge is a Burr arch truss type, with a load-bearing arch sandwiching multiple vertical king posts, for strength and rigidity. The bridge construction is cruder than the other two surviving covered bridges in Sullivan County, with each Burr arch formed from six straight beams set at angles instead of a smooth curve.
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)
The following Wikimedia
sister projects provide more on this subject: