Designed by David B. Steinman, of Robinson & Steinman, New York City, the Waldo-Hancock suspension Bridge is a significant example of Steinman's work. David Steinman is considered among the most important suspension bridge designers of the 20th century. He earned an engineering degree from Columbia University in 1909 and went on to apprentice with Gustav Lindenthal, then at work on New York's Hell Gate Bridge. In the 1920's, Steinman emerged as an outstanding and innovative suspension bridge designer.
The Triborough Bridge Project is a three-branched waterway crossing that connects Manhattan, the Bronx, and Queens at a junction of the East River and the Harlem River in New York City. The complex structure includes a suspension bridge from Wards Island to Queens, a vertical lift span from Randall's Island to Manhattan, a fixed span (designed to be convertible to a lift span) across the Bronx Kills, viaducts, and an innovative three-legged roadway interchange.
Built between 1819 and 1826, the Menai Bridge was the major structure on Britain's strategically important Holyhead Road connecting London with Holyhead and by sea to Ireland. Designed by Thomas Telford, the bridge's main span was 579 feet from tower to tower, the longest that had ever been attempted at this time. He used four sets wrought-iron eyebars to suspend the deck. These were made by William Hazledine at his Upton forge near Shrewsbury. Each bar was carefully tested in his Coleham shops before being pinned together and lifted into place.
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.
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.
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.
When a new road bridge was constructed alongside it, plans were made to demolish the Conwy Suspension Bridge. There was a national outcry and, since 1958, the bridge has been in the care of the National Trust and closed to vehicular traffic.
"An essential part of the human experience is to create an aesthetic atmosphere."
The George Washington Bridge represented a departure in suspension bridge design. Chief Engineer O.H. Ammann developed a system of stiffening trusses that offered greater flexibility and saved the project nearly $10 million. Initially, just six of the upper eight lanes were paved, but Ammann designed the bridge to easily accommodate a future lower level.
Swiss-born O.H. Ammann (1879-1965) was Chief Engineer for the Port Authority of New York and New Jersey during the bridge's construction.