Bridges

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

The Fink Deck Truss Bridge is thought to have been originally used on the Norfolk and Western mainline railway. It was moved to its present location and converted to a vehicular bridge over a railroad spur in 1893 when the Norfolk and Western mainline was moved. It was relocated again in 1985 to Lynchburg's Riverside Park to serve as a pedestrian bridge.

The Wheeling Suspension Bridge was the first bridge to span the Ohio River. It was initially completed in 1849, but destroyed by a tornado five years later. The bridge was rebuilt in 1856. The replacement bridge has the same general appearance of the original structure; the massive towers, anchorage housings, and island approach are all the original stone masonry.

Not only was Dunlap's Creek Bridge the first cast-iron bridge in America, it was the first metal bridge anywhere to use what its builder, Capt. Richard Delafield, U.S. Army Corps of Engineers, described as "standardized, interchangeable, manufactured parts." The bridge was built as part of the federal government's effort to make repairs on the National Road  before handing authority over to the states. Dunlap's Creek at Brownsville was an especially troublesome crossing, having destroyed three previous bridges since 1801.

The significance of the 15-mile Whitewater Canal was not in its ability to create a profit, but rather its effect on the economic growth of the Whitewater River Valley, considered the gateway to the interior of Indiana. Before the canal, travel was challenging. Most waterways in Indiana were only navigable by canoe, and the alternative - horse and wagon - was difficult, slow and expensive.  

The Delaware Aqueduct provided an important transportation link between the Pennsylvania's coalmines and New York's booming industrial marketplace. It is the earliest surviving work of John A. Roebling, who designed the Brooklyn Bridge  30 years later. The cable anchorage system first used on this project was also used on the Brooklyn Bridge. The aqueduct is patterned after Roebling's design of the Pennsylvania Canal over the Allegheny River, and is the oldest metal strand cable suspension bridge still standing in the U.S.