Research engineers at Columbia University launched the first of a series of experiments on Monday, Dec. 22, to provide the most sophisticated safety assessment ever conducted of New York's suspension bridge cables.

Watch footage of the experiment, conducted at Columbia University. (0:55)

The six-month experiment will assess the strength of the city's bridge cables with a corrosion-monitoring sensory system. The system includes a 20-foot mockup of a suspension-bridge cable that has been built in a laboratory on Columbia's Morningside Campus where it will be exposed to adverse weather conditions and studied for signs of stress. The mockup replicates a Williamsburg Bridge cable: It has a diameter of 20 inches and is made of nearly 10,000 steel wires, each five millimeters in diameter. During the experiment it will be subjected to 1.2 million pounds of tension.

The cable is encased inside an environmental chamber, which will generate a corrosive atmosphere with real-world conditions like acid rain, heat, cold and humidity. Using aggressive techniques, the engineers will expose the cable to the equivalent of decades of outdoor exposure in just six months.

The engineers have inserted dozens of corrosion-monitoring sensors into the mockup cable. If the sensors survive the test, they will be installed into the cables of New York's suspension bridges and generate immediate assessments of the bridges' safety.

"Some of those bridges have been built over a hundred years ago," said Raimondo Betti, professor of civil engineering and engineering mechanics, who is leading the experiment. "They have reached a stage now where age has become a crucial factor in keeping them functional."


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According to Betti, the failure of one suspension cable on a bridge such as the Williamsburg Bridge, the Brooklyn Bridge or the Manhattan Bridge would cause the failure of the entire bridge. "You can imagine what could [happen] if one of these bridges needed to be closed for a major repair. This would mean that the city basically shuts down," Betti said.

The goal of the experiment, which is funded by the Federal Highway Administration, is to find better ways of repairing or replacing the bridge cables in the hope of avoiding a costly shutdown or accident.

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