BROOKLYN BRIDGE

Description

Essentials about Brooklyn Bridge in brief

Brooklyn Bridge is undoubtedly the most famous bridge in New York City and one of the city’s landmarks. It spans the East River and connects the boroughs of Manhattan and Brooklyn. At the time of its completion in 1883, Brooklyn Bridge was the longest suspension bridge in the world and was considered the eighth wonder of the world due to its technical complexity. Today, the bridge has six lanes of traffic as well as a pedestrian and bike path on the level above. If you have a little time and want to enjoy a magnificent view of Manhattan, Brooklyn and the East River, you should definitely cross Brooklyn Bridge – ideally on foot or by bike to make as many photo stops as possible.

The history of Brooklyn Bridge

At the beginning of the 19th century, Manhattan was bursting at the seams. Year after year, thousands of immigrants came to New York City to realize their dream of a better life. Because housing in Manhattan became increasingly scarce, people moved to the other side of the East River to Brooklyn. By the end of the 19th century, Brooklyn was already the third largest city in America. The idea of a bridge between Manhattan and Brooklyn had therefore been discussed since the early 19th century, but always failed due to the adversities of the East River, which is not a river but an estuary with strong tidal currents and dense shipping traffic. A bridge without disturbing piers, crossing the estuary far above the ship masts in a large span, would have been the ideal solution, but seemed beyond all technical possibilities at the time.

The plan for today’s Brooklyn Bridge goes back to the German-American engineer John August Roebling from Thuringia. He had already constructed several suspension bridges and completed the Niagara Falls Suspension Bridge with a span of 260 meters in 1855. Roebling was also the owner of a rope factory that could manufacture wire ropes from high-tensile steel wires. He proposed a suspension bridge, for which he had also already drawn up plans with numerous details, including the two large granite towers with the four supporting cables.

The city councils of New York City and Brooklyn, however, reacted reluctantly. Roebling was able, however, to win over a businessman and newspaper publisher for his idea, who succeeded, after prolonged efforts, in obtaining a New York State law allowing a private company to build a bridge over the East River. In 1867, the New York Bridge Company was formed; two years later, Roebling’s plans were approved and he himself was appointed chief engineer for the bridge construction. Tragically, while inspecting the site designated for one of the towers, Roebling was the victim of an accident in which his foot was crushed by a ferry. He died just three weeks later as a result of blood poisoning. His son Washington then took over management of the project.

The construction of Brooklyn Bridge

The actual construction work on Brooklyn Bridge began at the beginning of 1870 with preparations for the foundations of the towers and the anchors. The excavation pits, which were up to 23 meters deep, were dug with the help of caissons, a method used for the first time in the USA that had not yet been fully mastered and whose medical problems were not understood at all. During the five years of civil engineering work, accidents and illnesses occurred repeatedly. Washington Roebling also fell ill with decompression sickness (diver’s disease) in 1872 while working in one of the caissons for the construction of the pier foundations. As a result, he had limited speech and was confined to a wheelchair. While he was only able to follow the further construction work with a telescope from his home, it was mainly his wife Emily who pushed the work forward. She was later to be the first person to cross the bridge after its completion.

In 1876, the first cable was stretched from one anchor across the towers and the East River to the other anchor, which was then used to build a narrow sagging footbridge. Spinning of the suspension cables began in early 1877. The spinning wheels ran back and forth until late 1878, pulling the more than 20,000 steel wires for the four suspension cables across the river. In March 1879, work began on the roadway girders, which took another four years. Since the railroad trains had become heavier in the meantime, Roebling had to provide reinforced braces in the truss structures. In total, about 6,000 workers were involved in the construction of the Brooklyn Bridge.

On the day it opened, May 24, 1883, 1,800 vehicles and 150,300 people were already crossing the new bridge. In order to convince the skeptical New York population of the stability of the structure, the Barnum Circus is said to have been sent across the bridge beforehand with 21 elephants for a load test (there are no confirmed sources for this, however).

Roebling applied the same basic principles to Brooklyn Bridge as he did to his earlier bridges. The bridge is supported by massive stone towers. The deck girder is a box truss structure, which in itself has high stiffness to prevent the dreaded vibration and twisting during storms. The track girder is not only suspended from the supporting cables by vertical hangers, but is also attached to the towers by stay cables.

The architecture and technology of Brooklyn Bridge

Brooklyn Bridge has a total length of 1,834 meters including the approach ramps, which had to be kept flat due to railroad use. In the main opening, it has a span of 486 meters and a clear height of 41 meters at the center of the deck girder.

The 26-meter-wide carriageway girder, which is divided into two halves, provides space for a total of six lanes, three in each direction. Originally, there were four lanes plus two tracks for trains on the inner lanes, but these were removed in 1950. A separate crosswalk for pedestrians and cyclists is located in the center of the level above the lanes.

The two towers, with neo-Gothic style elements, are made of granite. Roebling is said to have used the Gothic arched windows of the Divi Blasii Church in his German birthplace of Mühlhausen in Thuringia as a stylistic model. They have two pointed arch portals for the three carriageways on the two halves of the carriageway girder, which accordingly have two supporting cables each. At 48.50 meters above the roadway and 84.30 meters above mean high water, the towers of Brooklyn Bridge towered over all the buildings of the time except the spire of Trinity Church, which was a good meter taller.

Brooklyn Bridge was the first suspension bridge to use steel suspension cables. They were made on site using Roebling’s patented air spinning process. Roebling worked in a large safety factor by designing the suspension cable structure to carry six times the required load. This paid off especially when it was discovered during the work that a subcontractor had supplied substandard wires. These had already been installed and could not be removed. However, since this only reduced the load capacity to the point where the bridge could still handle four times the load, it was left at that.

Today, Brooklyn Bridge is still one of the most important traffic arteries in New York City. Around 120,000 vehicles, 4,000 pedestrians and 3,000 cyclists pass through the bridge every day. Use is restricted to vehicles up to 3.4 meters high and 2.7 tons total weight.