New technology can diagnose bridge stress months before human investigators—currently armed with binoculars— could ever detect them. BusinessWeek compares the small wireless sensors to stethoscopes, as they’re capable of gauging vibration, temperature and corrosion beneath the paint. Testers ride trucks over the sensors and monitor signals, listening for the small sounds that signal weakness.
The good news is that they're cheap: a 100-foot bridge can be checked for $8,000. The bad news is that there is a dramatic shortage of technicians who know how to use the technology. But BusinessWeek predicts that widespread implementation will come quickly in the wake of the Minneapolis bridge collapse; one study found that human inspectors found fatigue cracks only 4% of the time.