Meanwhile, he earned a reputation as a designer of suspension bridges, which at the time were widely used but known to fail under strong winds or heavy loads. Roebling is credited with a major breakthrough in suspension-bridge technology: a web truss added to either side of the bridge roadway that greatly stabilized the structure. Using this model, Roebling successfully bridged the Niagara Gorge at Niagara Falls, New York, and the Ohio River at Cincinnati, Ohio. On the basis of these achievements, New York State accepted Roebling’s design for a bridge connecting Brooklyn and Manhattan–with a span of 1,595 feet–and appointed him chief engineer. It was to be the world’s first steel suspension bridge.
Just before construction began in 1869, Roebling was fatally injured while taking a few final compass readings across the East River. A boat smashed the toes on one of his feet, and three weeks later he died of tetanus. He was the first of more than two dozen people who would die building his bridge. His 32-year-old son, Washington A. Roebling, took over as chief engineer. Roebling had worked with his father on several bridges and had helped design the Brooklyn Bridge.
The two granite foundations of the Brooklyn Bridge were built on timber caissons, or watertight chambers, sunk to depths of 44 feet on the Brooklyn side and 78 feet on the New York side. Compressed air pressurized the caissons, allowing underwater construction. At that time, little was known of the risks of working under such conditions, and more than a hundred workers suffered from cases of compression sickness. Compression sickness, or the “bends,” is caused by the appearance of nitrogen bubbles in the bloodstream that result from rapid decompression. Several died, and Washington Roebling himself became bedridden from the condition in 1872. Other workers died as a result of more conventional construction accidents, such as collapses and a fire.