suspension bridge: see bridge.

contract bridge: see bridge.

bridge, structure built over water or any obstacle or depression to allow the passage of pedestrians or vehicles. See also viaduct.

Early Bridges

In ancient times and among primitive peoples a log was thrown across a stream, or two vines or woven fibrous ropes (the upper for a handhold and the lower for a footwalk) were thrown across, to serve as a bridge. Later, arched structures of stone or brick were used; traces of these, built from 4000 to 2000 B.C., have been found in the E Mediterranean region. The Romans built long, arched spans, many of which are still standing. Bridges built during the Middle Ages usually rested on crude stone arches with heavy piers (intermediate supports) that were a great obstruction to river traffic, and their roadways were often lined with small shops.

The best known early American design is the New England covered bridge, since wood was abundant and cheap, and did not demand trained masons. Colonial American bridge builders were willing to run the risk of rot or fire in exchange for such savings in time and manpower. Beginning with Abraham Darby's bridge at Coalbrookdale in 1779, most bridges began to be built of cast and wrought iron. Robert Stephenson, an English engineer, designed and built a bridge of this type across Menai Strait in North Wales (1850). Another is Victoria Bridge across the St. Lawrence at Montreal. The disadvantage of cast iron for bridges is its low tensile strength.

Modern Bridge Designs

There are six basic modern bridge forms: the beam, the truss, the arch, the cantilever, the cable-stay, and the suspension. A beam bridge is made of long timber, metal, or concrete beams anchored at each end. If the beams are arranged in a lattice, such as a triangle, so that each shares only a portion of the weight on any part of the structure, the result is a truss bridge. An arch bridge has a bowed shape causing the vertical force of the weight it carries to produce a horizontal outward force at its ends. It may be constructed of steel, concrete, or masonry. A cantilever bridge is formed by self-supporting arms anchored at and projecting toward one another from the ends; they meet in the middle of the span where they are connected together or support a third member. In a cable-stayed bridge, the roadway is supported by cables attached directly to the supporting tower or towers. This differs from a suspension bridge, where the roadway is suspended from vertical cables that are in turn attached to two or more main cables. These main cables hang from two towers and have their ends anchored in bedrock or concrete.

The modern era of bridge building began with the development of the Bessemer process for converting cast iron into steel. It became possible to design framed structures with greater ease and flexibility. Single-piece, rolled steel beams can support spans of 50 to 100 ft (15-30 m), depending on the load. Larger, built-up beams are made for longer spans; a steel box-beam bridge with an 850-ft (260-m) span crosses the Rhine at Cologne.

Truss, Arch, and Cantilever Bridges

The truss can span even greater distances and carry heavy loads; it is therefore commonly used for railroad bridges. A large truss span like that over the Columbia River at Astoria, Oreg., can extend to 1,232 ft (376 m). If the truss is shaped into an arch, even longer bridges are possible; the Bayonne Bridge between New York and New Jersey, the Sydney Harbor Bridge in Australia, and the New River Bridge in West Virginia are the longest steel arch bridges, at 1,675 ft (510 m), 1,670 ft (509 m), and 1,700 ft (518 m), respectively. Concrete arch bridges tend to be somewhat smaller, the largest being the Krk Bridge in Croatia and the Gladesville Bridge across the Parramatta River at Sidney, Australia, at 1,280 ft (390 m) and 1,000 ft (305 m), respectively; the longest concrete arch bridge in the United States is the Natchez Trace Parkway Bridge in Franklin, Tenn., at 582 ft (177 m). The cantilever, however, is more common for spans of such lengths. The cantilevered Forth Bridge (1890) in Scotland was the first major structure built entirely of steel, the material that made possible its two record-setting spans of 1,710 ft (521 m) each. They remained the longest in existence until 1917, when the St. Lawrence River at Quebec Bridge was built; it has an 1,800-ft (549-m) span. The longest cantilever bridge in the United States is the Commodore John Barry Bridge in Chester, Penn., which has an 1,644 ft (501 m) span.

Cable-Stayed, Suspension, and Combination Bridges

The cable-stayed bridge is the most modern type, coming into prominence during the 1950s. The longest is the Tatara Bridge in Ehime, Japan, which has a 2,920 ft (890 m) span. The Ponte de Normandie in Le Havre, France, spans 2,808 ft (856 m); the Second Yangtze Bridge in Nanjing, China, spans 2,060 ft (628 m); and the Third Yangtze Bridge in Wuhan, China, spans 2,028 ft (618 m). The longest cable-stayed bridge in the United States is the Dame Point Bridge in Jacksonville, Fla., which has a span of 1,300 ft (396 m).

The suspension bridge is used for the longest spans. The earliest suspension bridges built in America were those constructed by the American builder James Finley. The design of suspension bridges advanced when J. A. Roebling, a German-born engineer who emigrated to the United States, developed the use of wire cables and stiffening trusses. His first completed suspension bridge spanned the Niagara River in 1854. He also designed the Brooklyn Bridge across the East River (completed 1883), which was the world's longest suspension bridge at the time of its construction, having a main span of 1,595.5 ft (487 m).

Today the longest spans in the world are suspended. The longest main spans are the Akashi Kaikyo Bridge, Hyogo, Japan, 6,529 ft (1,990 m); Izmit Bay Bridge, Marmara Sea, Turkey, 5,472 ft (1,668 m); Store Bælt Bridge, Denmark, 5,328 ft (1,624 m); Humber River Bridge, Hull, England, 4,626 ft (1410 m); Tsing Ma Bridge, Hong Kong, 4,518 ft (1,377 m); Verrazano-Narrows Bridge, New York City, 4,260 ft (1,298 m); Golden Gate Bridge, San Francisco, 4,200 ft (1,280 m); Hoga Kusten (or High Coast) Bridge, Västernörrland, Sweden, 3,969 ft (1,210 m); Mackinac Straits Bridge, Mich., 3,800 ft (1,158 m); Minami Bisan-Seto Bridge, Japan, 3,668 ft (1,118 m); Second Bosporus Bridge, İstanbul, Turkey, 3,576 ft (1,090 m); First Bosporus Bridge, İstanbul, Turkey, 3,524 ft (1,074 m); and George Washington Bridge, New York City, 3,500 ft (1,067 m).

Combination spans are often used to bridge even longer stretches of water. The San Francisco-Oakland Bay Bridge, noted for its three long spans, of which two are suspension spans and the third a cantilever, has a total length of 8.25 mi (13.2 km). The Chesapeake Bay Bridge-Tunnel has two 1-mi (1.6-km) tunnels along its 17.6-mi (28.2-km) length, and the 8-mi (12.9-km) Confederation Bridge, linking Prince Edward Island to the Canadian mainland, consists of three bridges. The longest combination spans are the twin Lake Ponchartrain Causeways near New Orleans, Louisiana, whose parallel roadways stretch nearly 24 mi (38 km). The longest cross-sea bridge is the Hangzhou Bay Bridge, 22.4 mi (36 km) long, which crosses the bay between Zhapu and Cixi, Zhejiang prov., China; the bridge combines causeway with two cable-stayed spans.

Movable Bridges

Movable bridges are generally constructed over waterways where it is impossible or prohibitive to build a fixed bridge high enough for water traffic to pass under it. The most common types of movable bridge are the lifting, bascule, and swing bridges. The lifting bridge, or lift bridge, consists of a rigid frame carrying the road and resting abutments, over each of which rises a steel-frame tower. The center span, which in existing bridges is as long as 585 ft (178 m), is hoisted vertically. The bascule bridge follows the principle of the ancient drawbridge. It may be in one span or in two halves meeting at the center. It consists of a rigid structure mounted at the abutment on a horizontal shaft, about which it swings in a vertical arc. The lower center span of the famous Tower Bridge in London is of the double-leaf bascule type. Because of the need for large counterweights and the stress on hoisting machinery, bascule bridge spans are limited to about 250 ft (75 m). The swing bridge is usually mounted on a pier in midstream and swung parallel to the stream to allow water passage.

Military Bridges

In wartime, where the means of crossing a stream or river is lacking or a bridge has been destroyed by the enemy, the military bridge plays a vital role. Standard types of military bridges include the trestle, built on the spot by the engineering corps from any available material, and the floating bridge made with portable pontoons.

bridge, card game derived from whist, played with 52 cards by four players in two partnerships.

Basic Rules

The cards in contract bridge rank from ace down to two; in bidding, suits rank spades, hearts, diamonds, and clubs. After all cards are dealt, so that each player holds 13 cards, the dealer begins the auction, which proceeds in rotation to the left. Each player must bid, pass, double (increase the value of the previously stated contract), or redouble (only after a double, further increasing the point value of the contract). A bid is an offer to win a stated number (over six) of tricks with a named suit as trump or with no trump. The lowest bid is one, the highest seven. Each bid, i.e., "one diamond," "one no-trump," "four hearts," must be higher than the preceding bid, with no-trump ranking above spades. Artificial bids are those that convey certain information to a partner and are not meant to be taken literally. The highest bid of the auction becomes the contract after three consecutive passes end the bidding. The player who first named the suit (or no-trump) specified in the winning bid becomes the declarer. The player to the left of the declarer leads any card face up, and the next hand, that of the declarer's partner, is placed face up on the table, grouped in suits. This is known as the dummy, and the declarer selects the cards to be played from this hand. The object of the game for both partnerships is to win as many tricks as possible, a trick being the three cards played in rotation after the lead. Suits must be followed, but a player who has no cards in the suit led may play any card. Highest trump or, if no trump card is played, highest card of the suit led wins. Points are awarded for the number of tricks won. Numerous conventions—generally accepted forms of bidding—are used in bridge, but the four standard ones are Blackwood, Gerber, Stayman, and grand-slam force.

Competitive Bridge

Duplicate bridge, in which the same prearranged hands are played by individuals, pairs, or teams of four, is the main form of competitive bridge. The laws of contract bridge are promulgated in the Western Hemisphere by the American Contract Bridge League, which holds various bridge tournaments. In international contract bridge matches the Bermuda bowl, the trophy for victory, is the emblem of the world championship. In Olympic years an olympiad championship is held by the World Bridge Federation and replaces the team tournament for the Bermuda bowl.

History

Bridge probably originated in the Middle East in the 19th cent. Auction bridge, one form of the game, was developed by the British in India and later was popular in England and the United States. It is still played but has largely been supplanted by contract bridge, which achieved popularity after important innovations were made in 1925 by Harold S. Vanderbilt. Its phenomenal popularity owed much to the activities of Ely Culbertson. The craze subsided but was later revived; books, tournaments, and newspaper columns on bridge abound. Culbertson devised the honor count system to evaluate a hand for bidding. The point count (or standard American) system introduced by Charles H. Goren in the 1940s has generally replaced honor count.

auction bridge: see bridge.

Verrazano-Narrows Bridge, vehicular suspension bridge, New York City, across the Narrows at the entrance to New York harbor, linking the boroughs of Brooklyn and Staten Island. Designed by O. H. Ammann, the bridge was completed in 1964. It is the longest suspension bridge in the United States, with a main span of 4,260 ft (1,298 m). There are two levels, each holding six traffic lanes.

Triborough Bridge, New York City, connecting the boroughs of Manhattan, the Bronx, and Queens. Completed in 1936, it comprises three separate sections—a bridge crossing the East River, a bridge spanning the Harlem River, and a fixed bridge across the Bronx Hills. Including the viaducts that connect the sections, the bridge's total length is c.3 mi (4.8 km).

Straits of Mackinac Bridge: see Mackinac.

San Francisco-Oakland Bay Bridge, double-decked structure, W Calif.; built 1933-36. It has a total length of 8.25 mi (13.2 km). From San Francisco it crosses the bay to Yerba Buena Island, where a tunnel connects with spans leading to Oakland and Berkeley. The bridge sustained significant damage in the severe 1989 October earthquake that hit the Bay Area.

Richmond-San Rafael Bridge, W Calif., c.4 mi (6 km) long, part of the network of bridges serving the San Francisco Bay area; completed in 1957. It provides an essential link between the east side of San Francisco Bay and the north coastal counties on the west side of the bay.

Rialto Bridge, Ital. Ponte di Rialto, bridge of Venice, NE Italy, over the Grand Canal, connecting Rialto and San Marco islands. Built between 1588 and 1591, it consists of a single marble arch and has arcades lined with shops.

Rama's Bridge: see Adam's Bridge.

Rainbow Bridge National Monument, 160 acres (65 hectares), S Utah; est. 1910. Rainbow Bridge, the largest natural bridge in the world, is a symmetrical, pink, sandstone arch, 309 ft (94 m) high, 33 ft (10 m) wide, with a 278-ft (85-m) span. Located in one of the most rugged and remote regions of the United States, it was discovered in 1909 by an expedition that set out to find the great stone arch rumored by the Native Americans. It is now accessible by boat from Lake Powell. See National Parks and Monuments (table).

Natural Bridge, small village, Rockbridge co., W Va., in the Shenandoah valley; founded 1774. Nearby is the famous Natural Bridge over the gorge of Cedar Creek. It is a limestone arch 215 ft (66 m) high with a span of 90 ft (27 m) and was once owned by Thomas Jefferson, who built a cabin there for visitors and kept a guest book. A public highway now crosses the bridge.

Mulvian Bridge: see Milvian Bridge.

Milvian Bridge or Mulvian Bridge, Latin Pons Milvius or Pons Mulvius. It was built by Marcus Aemilius Scaurus in 109 B.C. over the Tiber near Rome as part of the Flaminian Way. By defeating Maxentius here in A.D. 312, Constantine I became the unchallenged ruler of the West. It was here that Constantine saw the cross in the sky.

London Bridge, granite, five-arched bridge formerly over the Thames, in London, England. It is 928 ft (283 m) long and was designed by John Rennie and built between 1824 and 1831. The early wooden bridge (963-75) was replaced (1176-1209) by a stone bridge with houses and a chapel. The buildings were removed from 1756 to 1762. The bridge was many times damaged by fire and was finally removed in 1832 after the opening of a new bridge in 1831. In 1968, London Bridge was dismantled and purchased by Lake Havasu City, Ariz. In 1973 a new concrete bridge replaced the old one. London Bridge was the only bridge over the Thames in London until the construction (1739-50) of Westminster Bridge.

Golden Gate Bridge, across the Golden Gate from San Francisco to Marin Co., W Calif.; built 1933-37. Its overall length is 9,266 ft (2,824 m); its main span across the strait, 4,200 ft (1,280 m), is one of the longest bridges in the world. Joseph B. Strauss was the chief engineer.

George Washington Bridge, vehicular suspension bridge across the Hudson River, between Manhattan borough of New York City and Fort Lee, N.J.; constructed 1927-31. It is one of the longest suspension bridges in the world. Its main span is 3,500 ft (1,067 m) long and 250 ft (76 m) above the water. Cass Gilbert was the consulting architect, and O. H. Ammann was in general charge of the planning and construction. In 1962 a lower deck of six lanes was completed.

Confederation Bridge, Fr. Pont de la Confédération, bridge that joins Borden-Carleton in Prince Edward Island with Cape Jourimain in New Brunswick, Canada. Spanning the Northumberland Strait at its narrowest point, the bridge measures 8 mi (12.9 km) long and opened in 1997. Privately operated, it consists of the West Approach Bridge, with 14 piers; the East Approach Bridge, with seven piers; and the Main Bridge, which rests on 44 piers.

Chesapeake Bay Bridge-Tunnel, officially the Lucius J. Kellam, Jr. Bridge-Tunnel, 17.6 mi (28.2 km) long, across the mouth of Chesapeake Bay, E Va., connecting Cape Charles with Norfolk, Va. Opened in 1964, the original roadway consisted of a chain of low trestle bridges, two high bridges, and two tunnels (each 1 mi/1.6 km long) under the shipping channels. The tunnels are anchored on four artificial islands. A set of parallel bridges, but not tunnels, opened in 1999.

Charles River Bridge Case, decided in 1837 by the U.S. Supreme Court. The Charles River Bridge Company had been granted (1785) a charter by the state of Massachusetts to operate a toll bridge. The state later authorized (1828) a competing bridge that would eventually be free to the public. The Charles River Bridge Company brought suit against the competing company, claiming that the state charter had given it a monopoly. The court upheld the state's authorization to the other company, holding that since the original charter did not specifically grant a monopoly, the ambiguity in the contract would operate in favor of the public, thus allowing a competing bridge. The holding modified the Dartmouth College Case, which held that a state could not unilaterally amend a charter.

Calderón Bridge, site of a decisive battle in the Mexican revolution against Spain, fought on the Lerma River E of Guadalajara, Jalisco, Mexico. On Jan. 17, 1811, insurgents commanded by Hidalgo y Costilla met the royalists under Calleja del Rey. On the point of victory, Hildalgo's men were panicked by the explosion of an ammunition wagon. Their flight led to the collapse of the independence movement under Hidalgo.

Brooklyn Bridge, vehicular suspension bridge, New York City, southernmost of the bridges across the East River, between lower Manhattan and Brooklyn; built 1869-83. The achievement of J. A. Roebling and his son W. A. Roebling, it has a span of 1,595.5 ft (487 m). It was the first steel-wire suspension bridge in the world and was the world's longest suspension bridge at the time of its completion.

Bridge of Sighs, covered stone bridge in Venice, Italy, built in the 16th cent. to connect the ducal palace with the state prison. The prisoners were led over the bridge directly to prison after trial in the ducal palace.

Arlington Memorial Bridge, granite and concrete bridge across the Potomac River connecting the Lincoln Monument in Washington, D.C., with Arlington National Cemetery, N Va.; built 1926-32.

Adam's Bridge or Rama's Bridge, chain of shoals, c.18 mi (30 km) long, in the Palk Strait between India and Sri Lanka. At high tide it is covered by c.4 ft (1.2 m) of water. A steamer ferry links Rameswaram, India, with Mannar, Sri Lanka. According to Hindu legend, the bridge was built to transport Rama, hero of the Ramayana, to the island to rescue his wife from the demon king Ravanna.

or natural arch

Naturally created arch formation resembling a bridge. Most are erosion features that occur in sandstone or limestone. Some are formed by the collapse of part of a cavern roof. Others may be produced by entrenched rivers eroding through meander necks to form cutoffs. Still others are produced by exfoliation (separation of successive thin shells) and may be enlarged by wind erosion.

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Card game similar to whist. Bridge is any one of several games, including games such as auction bridge and contract bridge, which retain the essential features of whist: Four players participate, two against two in partnership. They play with a 52-card pack, all cards of which are dealt face downward one at a time, clockwise. When play begins, the object is to win tricks, consisting of one card from each player in rotation. The players must, if able, contribute a card of the suit led, and the trick is won by the highest card. All tricks taken in excess of the first six tricks are known as odd tricks. Before play begins, a suit may be designated the trump suit, in which case any card in it beats any card of the other suits. In all types of bridge a certain number points are needed to win a game, and two games won by the same team allows them to win the rubber.

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Natural area, southern Utah, U.S. Located on the Navajo Indian Reservation near the Utah-Arizona border, the monument was established in 1910 and occupies 160 acres (65 hectares). It centres on a rainbow-shaped bridge of pink sandstone 290 ft (88 m) above a creek that winds toward the Colorado River. The bridge is 275 ft (84 m) long and is one of the world's largest natural bridges. Embedded among canyons, the area is accessible only on foot, by horseback, or by boat on Lake Powell.

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Suspension bridge spanning the Golden Gate, San Francisco. From its completion in 1937 until the completion of New York's Verrazano-Narrows Bridge in 1964, it had the longest main span in the world, 4,200 ft (1,280 m). It remains incomparable in its magnificence. Its construction, supervised by Joseph B. Strauss (1870–1938), involved many difficulties: rapidly running tides, frequent storms and fogs, and the problem of blasting rock under deep water to plant earthquake-resistant foundations.

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Suspension bridge built (1869–83) over the East River to link Brooklyn to Manhattan island. It was designed by the cable manufacturer John A. Roebling and his son Washington. A brilliant feat of 19th-century engineering, the bridge was the first to use steel for cable wire and the first in which explosives were used inside a pneumatic caisson during construction. In 1869 John was killed in one of at least 27 fatal construction accidents; his son saw the project to completion. The bridge's main span of 1,595 ft (486 m) was the longest in the world to date. It opened to such fanfare that within 24 hours an estimated quarter-million people crossed over it, using an elevated walkway designed to give pedestrians a dramatic view of the city.

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