Friday, January 3, 2014

Suspending Space—A Bridge Unites Two Cities

Masons work on the Brooklyn Tower.
On January 3, 1870 construction began on the Brooklyn Bridge.
When opened more than 13 years later on May 24, 1883 at 5,989 feet the Bridge spanning the East River between Manhattan and Brooklyn was the longest suspension bridge ever constructed and remained so for twenty years.  It was also the first suspension to employ steel wire cables, among many other engineering innovations. 
A bridge connecting the two cities of New York and Brooklyn had been discussed for decades.  The problem was that any bridge had to accommodate heavy shipping use on the river.  A conventional draw bridges would not allow a large enough opening for the large sea going vessels operating on the river and no trestle or arched bridge could be built high enough.  By the end of the Civil War improved technology of the suspension bridge finally made the project feasible. 
John A. Roebling, a German born engineer had pioneered in constructing them.  The Delaware Aqueduct in Pennsylvania and a bridge crossing the Ohio River at Cincinnati were prototypes of the much larger Brooklyn project, for which Roebling began making plans and drawings in 1867. 
While conducting surveys for the bridge Roebling’s foot was crushed in an accident.  He contracted tetanus and died.  Some officials wanted to abandon the project without him. His son and assistant, 31 year old Washington Roebling, himself an experienced civil engineer, took over the project.  
Construction finally began under the younger Roebling’s personal supervision in January 1870. 
Digging the caissons to support the two stone towers of the bridge caused many workers to become disabled with what was then called caisson disease and is now called decompression sickness or the Bends. 
Early in construction Washington Roebling himself was badly disabled by the malady.  Unable to come personally to the job site, he watched progress from a window in his sick room and communicated to the job through his wife, Emily Warren Roebling herself a skilled mathematician and draftsman. 
Twenty-seven men were killed and many more maimed in the construction of the bridge. 
The bridge was built to accommodate pedestrians, carriages and wagons, street cars and a steam railway.  John Roebling designed it “six times stronger” than necessary to support the initial estimated weight of traffic, including three separate support systems.  This has enabled the bridge to endure and continue in use with the introduction of automobile traffic when most contemporary structures have long since been torn down and replace. 
The opening on May 24, 1883 was an occasion of wild celebration in the two cities.  President Chester Alan Arthur and New York Mayor Franklin Edison marched across the bridge as cannons fired continuous salutes and were met by Brooklyn Mayor Seth Low. 
Washington Roebling was still too ill to attend the ceremony, but the dignitaries went to his home to shake his hand and Emily Roebling led the first of 150,300 people and 1,800 vehicles that crossed the bridge that first day.  The waters of the East River were crowded by ships of all sorts, private yachts, and humble row boats.  That evening the largest fireworks display yet seen in America was shot off from the bridge towers, deck and assembled ships.

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