Brooklyn Bridge's 1,595.5-ft Span
Breaks All the World Records
Engineering News Record
ENR History January 18, 1999
1883
The Brooklyn Bridge, born in the mind of John Augustus Roebling, a German-born and educated
civil engineer, was the eighth wonder of the world, a bridge almost half-again longer than
the world's longest. Roebling, who began his professional life as a manufacturer of wire
rope, initially designed and built suspension bridges as a market for the material. His first
bridges were aqueducts for canals but his subsequent suspension bridges included a 810-ft
span over the Niagara Gorge and the Sixth St. Bridge in Pittsburgh. His career was topped
with a suspension bridge over the Ohio River at Cincinnati. Completed in 1867, it had a
record-breaking span of 1,057 ft and masonry towers.
In New York, there had been talk of a bridge linking Manhattan and Brooklyn since the
beginning of the 19th Century. Roebling had proposed a bridge with a 1,600-ft span in 1857.
A depression and the Civil War delayed decision, but in 1867 the New York Bridge Company
was formed, and he was its chief engineer. The project won final approval in June 1869, but
Roebling died the following month.
Not only was the bridge design entirely in hand, so was Roebling's civil engineer son,
32-year-old Washington Roebling, who had worked with his father on the Cincinnati bridge.
He succeeded his father as chief engineer.
Washington Roebling's first move was to clear the site of the Brooklyn pier for the caisson
that would take the pier to bedrock. The caisson was a massive structure for its time,
168x102 ft. Made of 12 x12-in. yellow pine, its roof was 15 ft thick and walls 9 ft thick,
tapering to 6 in. and fitted with a cast-iron cutting edge. Inside, 2-ft-thick walls divided
the chamber into six work compartments.
Held in place by a cofferdam, the caisson gradually sank to the riverbed as limestone blocks,
the beginnings of a masonry tower, were loaded onto it. Compressors on shore provided air
pressure to keep out water. Boulders were a constant problem, especially those under the
cutting edge and those so large they had to be broken up with blasting. Fires and blowouts
slowed the descent. Bedrock was reached at 44 ft below water for the Brooklyn pier in March
1871, after 14 months of work.
Roebling designed an even bigger caisson for the New York pier, which would have to go down
more than 70 ft. It had a roof 22 ft thick. Sinking began in October 1871, and work
progressed rapidly. By January, at 45 ft down with the pressure at 21 lb, workers began to
feel discomfort and pain, as they had in the Brooklyn caisson at that depth. As the caisson
sank further, symptoms became more severe. The first worker died at 71 ft when the pressure
was 34 pounds, and two more died in the next few feet. By May 1872, the caisson was in place
at 78 ft.
Roebling had spent considerable time in the New York caisson and suffered from the exposure,
experiencing an almost body-wide illness. By the end of 1872, he was disabled, in frequent
pain, barely able to speak and his sight failing. By then, the Brooklyn tower was 145 ft
high and the New York tower 60 ft. Late that year, he and his wife, Emily, went to Weisbaden,
Germany, for treatment at a spa. David McCullough, in his book The Great Bridge, says the
Roeblings stayed in Germany for six months and returned to live in the Trenton, N. J., home
of the Roebling wire works, for three years. According to construction folklore, the disabled
Roebling observed work on the bridge from a nearby house, and his wife acted as liaison.
In 1877, he did move into a house with a view of the bridge and, with the help of Emily
Roebling, guided its construction.
The anchorages, unlike the piers, presented no new problems but were imposing structures. At
each end of the bridge was a 60,000-ton masonry mass, 119 x 129 ft at the base. Within each
anchorage, four 23-ton anchor plates were embedded. From each plate, a chain of 12-ft anchor
bars emerged . Four sets of 38 bars in four tiers, to which the cable wires would be attached,
protruded from each anchorage.
The towers took three years to complete. At 276.5 ft above the water, they were higher than
the tallest New York office building. Spinning of the four bridge cables began in June 1877.
A wheel fixed to a traveler rope carried individual wires from anchorage to anchorage over the
towers. The spinning formed 278 wires into a strand. Nineteen strands were bound into an iron
wire-wrapped cable that was 15.75 in diameter.
The spinning went rapidly, with the four cables completed in October 1878. Wire rope
suspenders, steel stiffening trusses, girders, beams and roadway followed. The bridge opened
in 1883 to great acclaim. As the bridge entered its final stages, Washington Roebling's
health gradually improved. He returned to Trenton and lived to the age of 89.
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