Oral+Online+Presentation

media type="youtube" key="BSK9g4PbJgw" height="315" width="420"

The Breakthrough of the 19th Century: The Brooklyn Bridge.

The Brooklyn Bridge is a bridge located in New York City. The bridge connects the neighborhood of Brooklyn with Manhattan over the south east side of Manhattan on the East River. The Brooklyn Bridge is not just a bridge that crosses the East River; it is a symbol of New York City that also marks a milestone in history. Considered a brilliant feat of 19th-century engineering, the Brooklyn Bridge was a bridge of many firsts. It was the first suspension bridge to use steel for its cable wire. It was the first bridge to use explosives in a dangerous underwater device called a caisson. At the time it was built, the Brooklyn Bridge was also crowned the longest suspension bridge in the world until 1903. The Brooklyn Bridge was initially designed by German immigrant John Augustus Roebling, who had previously designed and constructed shorter suspension bridges in the United States. While conducting surveys for the bridge project, Roebling sustained a crush injury to his foot when a ferry pinned it against a piling. After amputation of his crushed toes he developed a tetanus infection which left him incapacitated and soon resulted in his death, not long after he had placed his 32-year-old son Washington Roebling in charge of the project. Washington Roebling also suffered a paralyzing injury as a result of decompression sickness shortly after the beginning of construction on January 2, 1870. This condition, first called "caisson disease" by the project physician Andrew Smith, afflicted many of the workers working within the caissons. After Roebling's debilitating condition left him unable to physically supervise the construction firsthand, his wife Emily Warren Roebling stepped in and provided the critical written link between her husband and the engineers on site. Under her husband's guidance, Emily studied higher mathematics, the calculations of catenary curves, the strengths of materials, bridge specifications, and the intricacies of cable construction. She spent the next 11 years assisting Washington Roebling helping to supervise the bridge's construction. In early 1883, the construction of the bridge was complete. In total, it had cost $15.1 million, doubling the initial budget. On May 23, 1883, the President Chester Arthur and Governor Grover Cleveland officially launched the Brooklyn Bridge before more than 14,000 guests. The toll to cross was set at a penny. On that first day, a total of 1,800 vehicles and 150,300 people crossed what was then the only land passage between Manhattan and Brooklyn. Emily Warren Roebling was the first to cross the bridge. The Brooklyn bridge belongs to the neo-Gothic Architectural style, has a Height of 84 m with a top Floor Height of 40 m. it was one of a kind back in the time of its construction, with a length of 1,053 m and a Width of 26 m, having a span of 486 m. over 23,000 km of cable hold the suspension bridge. The materials used for construction of the bridge are few and simple. The cables are steel and the towers are built of limestone, granite, and Rosendale cement. The construction of the bridge was another point of particular interest in the project. Bearing in mind the timing of construction of the project and the technologies available at that time, the problems associated with choosing a material are much more understandable. In fact, the material was designed specifically used for the construction of the bridge. The main problem was on the first steps of the project, the foundation. Not only did one have to get to the bottom of the river at more than 20 meters deep, but once they hit the ground, to dig the riverbed almost another 30 meters to find a ground of sufficient strength to withstand the weight of the structure. The solution seems surprising that it went to begin the construction of the towers before settling the foundation. Two huge boxes that were kept afloat by the air contained within it were placed moored on the river to ensure its correct position. Taking the surface of these cells is based on the construction of two towers on them. As the construction of the towers, was completed, the moving crates were sinking due to the weight of the granite. Once the crates arrived at the bottom of the river, a team of operatives began to dig on the muddy bottom of the river, allowing each box to continue moving toward the ground while construction of the two towers continued on the surface. The boxes were kept free of the water around them through a pipe system which introduced compressed air inside it. Another pipe system allowed the removal of mud to the surface. In 1944 began a major reconstruction of the bridge that would last 20 years. Trams were withdrawn, the pillars were reinforced, cables and main cables were added, and new suspension was extended from two to three lanes in each direction for vehicles and the construction of new access roads. Currently the bridge has two levels. The bottom two carriageways of three lanes each circulate on a daily basis more than 145,000 vehicles. The top level is a gateway for pedestrians and bicycles. The Brooklyn Bridge is one of the most transited bridges in New York City and is also one of the main touristic places of the city as well.