The Brooklyn Bridge was built with fraudulent wire, and it held anyway.
During construction, engineers discovered a supplier had slipped substandard wire into the Brooklyn Bridge's main cables. It was too late to take it out. The bridge survived because its designer had made it six to eight times stronger than needed. It was finished by a chief engineer watching through a telescope, with his wife as his link to the site.
John A. Roebling designed the bridge to cross New York's East River, then crowded with ferries, with a main span of about 486 metres, the longest suspension bridge in the world when it opened on 24 May 1883. Before construction even started, a ferry crushed his foot during surveying in 1869, and he died of the resulting tetanus infection. His son, Washington Roebling, took over as chief engineer.
The towers stand on huge timber caissons, sunk by workers digging inside them in compressed air. Many fell ill with a then-mysterious condition the project physician named 'caisson disease', now known as the bends. Washington Roebling was himself left partly paralysed. He directed the rest of the work from his apartment, famously watching through a telescope, while his wife, Emily Warren Roebling, carried messages to the engineers and mastered cable construction and the relevant mathematics. She was, officially, the first person to cross the finished bridge.
The wire scandal came during cable spinning. Tests showed that a contractor, J. Lloyd Haigh, had substituted inferior wire: of 80 rings tested, only five met the standard. The cables already strung could not be replaced, so engineers left the bad wire in and added 150 extra wires to each cable. Roebling calculated that the bridge was now four times as strong as necessary, rather than six to eight.
That generous safety margin was typical of the age, when engineers did not yet understand the aerodynamics of bridges. The four main cables each bundle 5,282 steel wires, the first use of this bundling in a suspension bridge. An estimated 27 men died building it, and it cost 15.5 million dollars. Haigh's suspender cables were finally replaced in the 1980s.
Source: Wikipedia — Brooklyn Bridge · Text summarised from Wikipedia (CC BY-SA 4.0)
