The Brooklyn Bridge, dubbed one of the eight wonders of the world, was used to unite Brooklyn to Manhattan. John A. Roebling was made chief engineer of what was once the longest bridge in the world, at 6,016 feet (1834 m).^[1] The bridge's construction was started on January 3, 1870 and was completed on May 23, 1883.^[2]

The bridge took 264 men working 24 hours a day 14 years to construct.^[3] Building the longest suspension bridge came with many complications such as deaths, fires, illnesses, and controversy.

It remains one of the most processed images by Kodak and is considered an American monument.^[4]

Contents 1 Construction History 1.1 Early Beginnings 1.2 Construction Considerations 1.3 Wire Rope 1.4 Anchorages and Towers 1.5 Spinning of Cables 1.6 Completion 1.7 Accidents and Deaths 1.8 Criticisms 2 Refurbishment/Recent Projects/Renovations 3 References 4 Additional Resources

[edit] Construction History

[edit] Early Beginnings

John Roebling, the initial chief engineer to be named for the project, had previous experience as the first manufacturer of wire rope. Structures built under his supervision included mostly aqueducts of canals and suspension bridges, such as the 810-foot (247-m) bridge over the Niagara Gorge and Sixth Street Bridge in Pittsburgh.^[5]

Roebling first conceived of the Brooklyn Bridge when he was stranded on a ferry on East River. He proposed plans for a bridge spanning 1,057 feet (322 m) but its approval was delayed.

Once Roebling's plans for a bridge between Manhattan and Brooklyn was approved, the New York Bridge Co. was formed. Construction was to begin in 1869.

Roebling knew the significance the bridge would carry as a response to the growing population. He said it would be "of incalculable value in a crowded commercial city," and that "the structure [would] forever testify to the energy, enterprise and wealth of that community which [would] secure its erection."^[6]

One of the most important contributions that Robeling made to the bridge was the idea that it would be built with steel wire in lieu of iron. But his dreams for the bridge ended abruptly as he was determining where the bridge should be built while he was standing on a ferry slip. The ferry docked and crushed his foot. He died of gangrene two weeks later.

Washington Roebling, Roebling's 32-year old son, was named chief engineer of the enormous task.^[7]

[edit] Construction Considerations

The building of the Brooklyn Bridge required a lot of originality as the bridge required materials never used before.

The first line of business was to clear the Brooklyn pier so the air-locked caisson could be sunk into the riverbed. The 168- by 102-foot (51- by 31-m) long caisson was waterproofed with oakum and held firmly in place by a cofferdam, easing its into the riverbed where the masonry tower base would be built.

The caissons were 3000-ton cylinders that allowed the workers to clear away silt with the help of compressed air under the riverbed. The workers dug up 78.5 feet (24 m) below the riverbed on the Manhattan side and 44.5 feet (14 m) on the Brooklyn side.^[8] Water was kept out with the help of compressors that provided air pressure and large rocks, which proved a constant problem, had to be blasted. This portion of the project took almost 14 months of work.^[9]

[edit] Wire Rope

Roebling decided on wire ropes made from strands of metal due to the fact that they were able to move together in a way that would enhance the strength of the material. He used steel wires and spun them on site to ensure they would meet length requirements.

Roebling designed the bridge in a way that it could be held by four 15.75-inch (40-cm) steel cables. Washington tested the strength of the wires at 160,000 pounds per square inch (1,103,161 kPa) (2X iron). As an additional measure he had the wires galvanized or coated with zinc.^[10] The use of steel was a first in the case of suspended bridges and many criticized Roebling's lack of scientific proof that they would hold successfully.

[edit] Anchorages and Towers

This part of the construction was much easier, with four 23-ton anchor plates were used for the base of 60-ton masonry bases. The cable wires were attached to four sets of 38 bars from which the anchorage protruded. Three years later, the towers were complete, at 2,765 feet (843 m) above water.

[edit] Spinning of Cables

Wires were spun in 19 strands and bound together to create a cable 15.75 inches (40 cm) in diameter. This was completed in 1878 with the help of wire rope suspenders, steel stiffening trusses, girders and beams.

The bridge, which comprised 14,400 miles (23,175 km) of wire and measured at 6,016 feet (1,834 m), rising to 135 feet (41 m) above water, consisted of four lanes for carriages and horseback and an elevated promenade for pedestrians and bicyclists.^[11]

[edit] Completion

The Brooklyn Bridge, also known as the Great East River Bridge was completed in 1883. On May 23rd, Roebling's wife, Emily, rode across his completed project with a rooster in her lap to symbolize the victory of the feat. The bridge was opened to the public the next day. It cost $15.1 million to build.^[12]

[edit] Accidents and Deaths

At least 27 to 30 people died during the building of the bridge. In a cable-rigging incident, the cable strand came loose upon adjustments and flew into the East River, decapitating one worker and knocking another off the anchorage in June 1878.^[13]

Most of the men working in the caissons either died or became affected by caisson disease, also known as the bends. The disease acquired the name for its debilitating side effect of contorting the body. It occurred when nitrogen bubbles got into the bloodstream. Muscular paralysis occurred in as much as 15 percent of the men, and Roebling himself, who performed manual labor in the caissons, was even diagnosed with the disease. Roebling was steadfast in his goal, and continued to watch the construction from a windowed bedroom nearby. His wife, Emily, often executed his wishes to the builders.^[14]

[edit] Criticisms

While the bridge was often marveled at as a monument, there were some issues that drew criticism with the public. Most notably was the cheaper wires used for the cables. To Reobling's dismay, the wire contractor had been using a weaker wire. Roebling, however, tested the durability and found that it was sufficient, being five times stronger rather than six times stronger than necessary.^[15]

Roebling was also criticized for using steel instead of iron but a board on inquiry found that his scientific proof that steel would support the dead weight four times over silenced his critics.^[16]

[edit] Refurbishment/Recent Projects/Renovations

• New York spent US$150 million to retrofit the bridges, a protection measure against earthquakes.^[17]
• A reconstruction project took place between 1944 and 1954 where the trusses were strengthened. Horizontal says were installed between the core cables and the railroad tracks removed to make the lanes wider.
• A re-decking project was completed in 1999 by the New York City Department of Transportation after concrete was found chipping from the steel girding.
• Crumbling concrete made further constructions necessary after crumbling concrete and rusted joints were located on the approaches. A US$725 million ramp rebuilding project was scheduled, the completion date set for 2011.

[edit] References

1. ↑ http://www.nyc.gov/html/dot/html/bridges/bridges.shtml#brooklyn
2. ↑ Feuerstein, Gary. Engineering News Record. Brooklyn Bridge's 1,595.5-ft Span Breaks All the World Records. Endex.com, 2008-09-23.
3. ↑ Information compiled by: Feuerstein, Gary. Brooklyn Bridge Facts, History, and Information. Endex.com, 2008-09-23.
4. ↑ Feuerstein, Gary. Engineering News Record. Brooklyn Bridge's 1,595.5-ft Span Breaks All the World Records. Endex.com, 2008-09-23.
5. ↑ Feuerstein, Gary. Engineering News Record. Brooklyn Bridge's 1,595.5-ft Span Breaks All the World Records. Endex.com 2008-09-23.
6. ↑ Information compiled by: Feuerstein, Gary. Brooklyn Bridge Facts, History, and Information. Endex.com, 2008-09-23.
7. ↑ Keller, Allan.The Great Brooklyn Bridge. American History Illustrated, Endex.com, 2008-09-23.
8. ↑ NYCRoads.com Brooklyn Bridge: Historic Overview. NYCroads.com, 2008-09-23.
9. ↑ Feuerstein, Gary. Engineering News Record. Brooklyn Bridge's 1,595.5-ft Span Breaks All the World Records. Endex.com, 2008-09-23.
10. ↑ Information compiled by: Feuerstein, Gary. Brooklyn Bridge Facts, History, and Information. Endex.com, 2008-09-23.
11. ↑ NYCRoads.com Brooklyn Bridge: Historic Overview. NYCroads.com, 2008-09-23.
12. ↑ Information compiled by: Feuerstein, Gary. Brooklyn Bridge Facts, History, and Information. Endex.com, 2008-09-23.
13. ↑ Feuerstein, Gary. fckLREngineering News Record. Brooklyn Bridge's 1,595.5-ft Span Breaks All the World Records. Endex.com, 2008-09-23.
14. ↑ American Icon: History of Brooklyn Bridge, 2008-09-23.
15. ↑ Information compiled by: Feuerstein, Gary. Brooklyn Bridge Facts, History, and Information. Endex.com, 2008-09-23.
16. ↑ Information compiled by: Feuerstein, Gary. Brooklyn Bridge Facts, History, and Information. Endex.com, 2008-09-23.
17. ↑ Information compiled by: Feuerstein, Gary. Brooklyn Bridge Facts, History, and Information. Endex.com, 2008-09-23.

[edit] Additional Resources

• The Great Bridge, David McCullough. Simon & Schuster, 1972, New York, p.49
• Smith, H. Shirley. The World's Great Bridges. Phoenix House: London, 1964.
• Hopkins, H.J. A Span of Bridges. Praeger Publishers: Washington, 1970. p.220-227.
• McCullough, David. The Great Bridge. Simon & Schuster: New York, 1972. p.49