CONSTRUCTION |
Designer
of the Bridge
The
designer of the Verrazano-Narrows Bridge, Othmar Hermann Ammann
(1879-1965) was a graduate of the Federal Polytechnic Institute
in Zurich (1902), who immigrated to the United States in 1904 and
became a naturalized citizen in 1924. An authority on bridges, he
also designed the George Washington, Bayonne, Triborough, Throgs
Neck, and Bronx-Whitestone bridges. |
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Othmar
H. Ammann, left, with Triborough Bridge and Tunnel Authority
Chairman Robert Moses on October 10, 1961, the day the first
steel was erected for the Staten Island tower.
MTA
Bridges and Tunnels Special Archive
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Components
of a Suspension Bridge
The
deck - carries traffic
The cables - support the deck
The tower foundation - support the towers
The anchorages - hold the ends of the cables
in place |
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The
Deck
To
form the deck, sixty seperate chunks of steel, each the size of
a ten-room ranch house and weighing four hundred tons, had to be
lifted 220 feet in the air to link the 6,690 foot span. Each steel
piece, in addition to several smaller ones, would be linked to the
suspender ropes dangling from the cables and would finally be linked
together horizontally across the water. Seasonal contractions and
expansions of the steel cables cause the double-decked roadway to
be 12 feet lower in the summer than in the winter. |
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| MTA
Bridges and Tunnels Special Collection, 1990. |
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| Library
of Congress, HAER, NY 24-Brok, 57-23 |
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| The
Cables
The
central element in any suspension bridge are the cables. The four
cables of the Verrazano-Narrows Bridge weigh 39,192 tons. To create
the cables, 26,108 wires were carried across the Narrows. Each wire
had a specific location side by side and one on top of the other
and a specific tension. The cable work took from March 4, until
August 22, 1963 and involved 600 men working 71/2 hour days, five
days per week. After the cables were compacted and banded they measured
35 7/8 inches in diameter and could sustain a minimum of 220,000
pounds per square inch.
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| MTA
Bridges and Tunnels Special Collection, 1990. |
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The
Towers
The
4,260-foot distance between the Verrazano-Narrows Bridges towers
is so far that compensation for the curvature of the earth was necessary.
The monumental 693-foot high towers are 1 and 5/8 inches farther
apart at their tops than at their bases. Each tower weighs 27,000
tons and is held together with three million rivets and one million
bolts. |
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| MTA
Bridges and Tunnels Special Collection, 1990. |
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| Library
of Congress, HAER, NY, 24-Brok, 57-11 |
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The
Tower Foundations
On
the Staten Island side, the tower foundations lie 105 feet below
mean high water. Before construction could begin, sand islands were
built to serve as working areas. On the islands, steel-and-concrete
open-dredge caissons with 66 circular wells, each 17 feet in diameter,
were constructed. The massive caisons, each measuring 129 by 229
feet, were sunk to rest at depths beneath the bay bottom at which
the soils had been predetermined to be weaight-bearing. Atop tha
caissons, the tower pedestrals were built. |
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| MTA
Bridges and Tunnels Special Collection, 1990. |
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