ENGINEERS routinely inspect bridges and other structures for cracks and corrosion. But because they can’t always be there in person, one highly intelligent bridge knows what to do when trouble arises: send them an e-mail.
The long spans and slender cables of the Jindo Bridge in South Korea are dotted with a small army of electronic sentinels — tiny wireless sensors and microprocessors that monitor the bridge’s structural health. The network constantly analyzes factors like vibration, wind and humidity, and promptly reports anomalies to a computer that then passes along the news. (As of last week, the bridge said it was just fine.)
Wireless systems like the Jindo Bridge network, a prototype now in its third year of testing, won’t replace human monitoring. But the data collected by the network can help bridge owners make informed decisions, said John W. Wallace, a professor of civil and environmental engineering at the University of California, Los Angeles, and director of the structural/earthquake engineering research lab there.
Traditionally, most systems that monitor structures’ responses to earthquakes or strong winds have been wired ones. But wireless alerts may one day be an alternative.
“Wired monitoring systems are expensive,” said Dr. Jerome P. Lynch, director of the Laboratory for Intelligent Structural Technology and an associate professor at the University of Michigan. “You have to route kilometers of wire for power and data.”
The wireless systems may also be attractive because of their sophisticated power-management software, which improves battery performance, he said. Sensors can also extend battery life by harvesting power from the sun and the wind — and even from vibrations.