Wireless sensors tell of bridge's condition

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 analyzes factors like vibration, wind and humidity, and promptly reports anomalies to a computer that then passes along the news.

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.

Most systems that monitor structures' responses to earthquakes or strong winds have been wired ones. But wireless alerts may one day be an alternative.