The Rogue River Bridge was the most advanced concrete bridge in America when it was built. Distinguished bridge engineer Conde McCullough employed the techniques of Frenchman Eugene Freyssinet to create thin, graceful concrete arches for this seven-span structure.
Pre-compression of the concrete arch was achieved and, as a result of its success, pre-stressing became one of the hallmarks of American bridge building techniques.
When opened in 1909, the 1,470 foot long main span of the Manhattan Bridge was the third longest suspension bridge span in the world, after the nearby Brooklyn and Williamsburg Bridges. The Manhattan Bridge has two 725 foot long suspended side spans for an overall length of 2,920 feet. The bridge deck is supported by 4 main cables of 20.75 inch diameter, each composed of more than 35,000 individual wires. The bridge deck is stiffened by four parallel trusses of 24 foot depth, hinged at the towers.
The Mackinac (pronounced "Mack-in-awe") Bridge (1957) spans the Straits of Mackinac between Lake Michigan and Lake Huron, connecting the Lower and Upper peninsulas of Michigan. Prior to the construction of the bridge, a fleet of nine ferries would carry as many as 9,000 vehicles per day, with traffic backups stretching as long as 16 miles.
Ancient Chinese literature refers to the Zhaozhou Bridge as a "crescent moon rising from the clouds" or a "rainbow in the sky." Throughout its history, it has been known as the Anchi or Anji Bridge (literally "safe crossing"), the Dashi Bridge ("big stone"), and the Dashiqiao ("great stone") Bridge.
In the 1850s, the Lexington and Danville Railroad began building a suspension bridge over the Kentucky River. The bridge was designed by John A Roebling. Due to unforeseen increases in train loads, the Roebling bridge was never completed. The High Bridge would then be built 20 years later on the existing foundations.
The workforce consisted of less than 100 men, yet they finished construction in just 94 days. Such speed was possible due to the elimination of scaffolding. Instead, iron rods were used to support construction of the trusses between the towers, and workers moved back and forth across the rods. A dangerous venture, yet no workers were seriously injured.
A 214-foot single-span covered wooden bridge, built above the cribs of stone in the AuSable River that served to break log jams and ice floes, collapsed during the winter of 1875 under the weight of a three-foot snowfall and high winds. The "Upper Bridge" (pictured) was built in its place.
In 1866, the Covington and Cincinnati Suspension Bridge was the largest suspension bridge in the world. Also called the Ohio Bridge, it was officially renamed the John A. Roebling Bridge in 1983. It was the first permanent bridge over the Ohio River and the only public project in America financed by private investors during the Civil War.
Renowned bridge designer John A. Roebling proposed the structure in 1846; but building the bridge would become a 20-year saga, with heated lobbying both for and against the crossing.
Put in service in 1937, this world-renowned bridge, conceived by Joseph Strauss and designed largely by Charles Ellis, was the longest single span (4,200 feet) in the world for a quarter century.
As with many civil engineering projects in their conceptual stages, naysayers scoffed at the Golden Gate Bridge. They said it would be technically unfeasible or too expensive to bridge the Golden Gate, a 1.7-mile-wide opening separating the Pacific Ocean from the San Francisco Bay. They said that the channel was too deep; the tides and winds too strong; the span too long.
"For 273 years, the little stone bridge that carries Frankford Ave. across Pennypack Creek has been doing its humble job with a minimum of attention..."
- Gerald McKelvey, The Philadelphia Inquirer, September 16, 1970
