Photo Credit: Library of Congress
Beginning a study of historic bridges is to embark on a journey that can literally take the traveller all over the world. Many fascinating adventures can be planned by researching and mapping the location of bridges you might wish to explore. When you find one, there is much to be discovered about the bridge itself, from background information about its construction, to its purpose and all of the details that make up its structure.
Unfortunately, bridges that aren't protected by public institutions such as the National Register of Historic Places risk falling into disrepair, leading generally to demolition. Historic bridges are an endangered resource that require protection and funding for upkeep. Nevertheless, they constitute a surprisingly rich and interesting collection with a mystique that appeals to all generations. Best of all, they are accessible. You don't need a ticket to see a bridge, although you may sometimes have to pay a toll to get to the other side.
The history of bridge building in the world has always been characterized by the quest for better design and strength. The Brooklyn Bridge in New York City, opened in 1883, was the first suspension bridge to use steel wire cables instead of iron. Sailors accustomed to high rigging were hired to string the 1,500 suspenders for the deck.
The risk above the bridge was matched by the danger below. To build the two giant stone towers, timber caissons were sunk deep into the riverbed and filled with concrete by crews of men in air-locked dungeons. Digging until they reached bedrock, some of the workers (dubbed “sand hogs”) were ultimately afflicted by decompression sickness, the same hazard risked by deep-water divers when rising to the surface too quickly. The condition disabled Brooklyn’s engineer, Washington A. Roebling, resulting in the completion of the work by proxy through his wife Emily, also a trained engineer. All told, at least 20 people lost their lives in the 14 years it took to build the Brooklyn Bridge.
Abutment: Part of the substructure of a bridge that holds up each end
Pier: A support between the abutments
Caisson: A filled metal tube that acts as a pier
Span: A section of the bridge between the piers and abutments
Skew: An angled bridge
Deck: Bridge surface that carries traffic
Truss: Triangular framework often constructed of metal
Plaque: A decorative label placed on a bridge to identify the bridge builder and often including officials, contractors, and engineers
NEW YORK, USA
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