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Hum110 wake tech week 7c2 workforces bridge
- 1. The Building of the Brooklyn Bridge
Editor's Notes
- In 1869, President U.S. Grant signed a bill authorizing the construction of a bridge between Manhattan and Brooklyn. Work began on January 2, 1870 on the Brooklyn Tower of the Bridge. Before the completion of the bridge there were 20-30 reported deaths. Many more died but the deaths of day workers were not reported. The bridge ’s designer himself was killed. The great explosion, the Caisson Fire and the Steel Cable failures resulting in the discovery of contractor fraud also resulted in casualties. Another non-fatal casualty was Washington A. Roeblings, son of John Augustus Roeblings and his replacement as head engineer on the project. Bridge Design Engineers were John Augustus Roebling and Wilhelm Hildenbrand John A. Roebling, was appointed chief engineer for the project on May 23, 1867 at a salary of $8000 per year. Other salaries were… Masons were paid $30/week Fitters received $12/week for what have been the most dangerous work Common laborers received $10/week. (Brooklyn Bridge. Dir. Ken Burns. Nar. David McCullough, PBS Home Video, 1981, DVD.) John A. Roebling suffered a fatal accident on July 6, 1869 at the Brooklyn Fulton Ferry slip. He died on July 22, 1869, of lockjaw, an infection resulting from the accident in which his foot was crushed during observations to determine the exact location of the Brooklyn tower. Roebling declined anasthetic for the amputation of his toes crushed in the 9 July 1869 accident, so he could continue to supervise the project immediately after the operation. Some characteristics of the Bridge… The Brooklyn Tower:39;6" below mean high tide Built on bedrock at 90 ’ Each tower had… 2 water shafts 2 man shafts 2 supply shafts pipes for gas, air and drinking water Initial rate of caisson excavation and lowering - 6 inches per week (DBS) Workforce on Brooklyn Tower - 360 (DBS) Height achieved by stones and mud from "Big Blowout" in Fall 1870 - 500 feet (DBS) Bridge is made public - 1874 (interest paid to subscribers) Brooklyn tower completed - June 1875;New York tower completed - July 1876 The Brooklyn Bridge opened - May 24,1883, 2:00 PM There was a protest on Opening Day - Irish workers dissatisfied that Opening Day coincided with Queen Victoria ’s birthday. (DBS) Initial Bridge Toll - 1 cent on Opening Day, 24 May, 1883, 3 cents thereafter (Facts from WGBH, Boston More at their website) People crossing the bridge on opening day - 150,300 Total number of vehicles crossed on the first day - 1,800 Vehicles charge on Opening Day - 5 cents Cost of original structure $15,100,000 Brooklyn Bridge Construction Accidents Some of the worst accidents of the bridge construction happened during the cable rigging. In June of 1878, a cable strand secured at the New York anchorage broke loose during adjustment. The strand flew over the New York tower and into the East River, taking off the top of one rigger ’s head and knocking another off the anchorage along the way. Another rigger was guiding wire onto a drum. He kicked at it to keep it in line, and his foot was caught. His leg was wrapped around the drum, killing him almost instantly. Several others died due to falls or falling equipment. At least three men died of the bends (caisson disease) during the caisson work. Cables Four 15 3/4-inch cables are the backbone of the bridge. The decision to use steel instead of standard iron wire was a revolutionary proposal. Steel was regarded as a suspect material, not yet proven over time as was iron. In fact, at the time of the construction of the Brooklyn Bridge, the use of steel in any structure in Great Britain was illegal. Steel would be vindicated as a tensile material in the Brooklyn Bridge, and, at the same time, as a compression material in the St. Louis Bridge. Washington Roebling specified a tested wire strength of 160 ksi (twice that of iron), and required that the wire be galvanized, to resist corrosion by the salt air. Unfortunately, much of the wire that was actually used was not to specifications. The wire contractor had been substituting weaker (and cheaper) Bessemer steel for the desired crucible-cast kind. While justifiably outraged at the scam, Roebling had initially designed the cable to be six times stronger than necessary. He calculated that the condemned wire was still five times stronger than it had to be, and there was no need to remove the strands already in place. The four cables support a dead weight (the deck and suspenders) of 13,240 kips--3,410 kips per cable. Each cable has an ultimate strength of 24,600 kips, but the maximum load on a single cable rarely exceeds 6,000 kips. This gives us a present-day factor of safety of about our. The river span is 1,595.5 feet, and the maximum sag over the river is about 130 feet. The length of each supported land span is 930 feet.
- Caisson Disease (Bends)The nemesis of all compressed-air workers was the bends. At the time of the Brooklyn Bridge construction, little was known about the causes of these painful attacks--and little could be done to prevent them. Nearly all caisson laborers were inflicted with the bends to a certain extent. In the case of the Brooklyn Bridge, three people died and fifteen percent of those who got the bends were paralyzed to some degree. Some success with fighting the bends was achieved by a Dr. Janimet, on the St. Louis Bridge. He was the first American to hit upon the idea of slow decompression (the British and French had known it for years). Unfortunately, James Eads, the builder of the St. Louis Bridge, had a falling out with Washington Roebling and never imparted his discovery. Fear of the bends was what caused Roebling to halt the excavation of the New York caisson; he estimated that upwards of eighty men would die if he tried to excavate any further. Washington Roebling himself did not escape the construction of the caissons unharmed. He had always been a man who liked to be on site during the construction, and often he could be found inside the caisson instructing others what to do and many times doing manual work himself. Washington Roebling actually spent more hours in the working chamber than anyone else for fear that any slip might prove to be disastrous. One afternoon in the summer of 1872, Washington Roebling had to be carried out of the caisson with caisson disease. From this point on, he remained painfully paralyzed and became known as "the man in the window," for he never returned to the site of the Brooklyn Bridge, but watched it through a spyglass from his townhouse. Roebling was determined to see the construction of the bridge to completion. He directed the construction from his townhouse; his wife Emily Roebling acted as an intermediary between the Colonel and his bridge.
- New York Legislature considers a bill to build a bridge over the East River - Bill passed by the New York State Legislature for construction - 1866 Why? Manhattan was unable to support a larger population. A larger workforce was needed to sustain the City ’s explosive growth stimulated by the American Civil War. There were ferries, but anyone who has traveled from Brooklyn to Manhattan and from Staten Island to Manhattan will tell you that a bridge is faster and more reliable. Brooklyn's population in 1860 was 266,000 Brooklyn's population in 1870 was 396,000 - This represented a 50% increase over the decade making Brooklyn the fastest growing city on the country. Manhattan is an island about twelve miles long. Space is limited. A workforce is needed to allow for expansion but there is nowhere to house them. Tenements sprout, but an increasingly affluent workforce wants space, homes- The American Dream. The opening of Brooklyn as a “bedroom community” for the New York workforce created what may be the first suburb. It set American society on a path that required public and then personal transportation. First specialized technical skills had to be developed so that technology could change society. The logical outgrowth of this is the development of Levittowns. “Bedroom communities’ for New York and Philadelphia.