An Intelligent Bridge

A new highway bridge in Minnesota incorporates hundreds of sensors to increase safety and cut costs.

Several kinds of technologies are built into the bridge. A network of 323 sensors monitors the span for corrosion in the concrete, strained joints, or other structural weaknesses. The anti-icing system tracks the roadway's temperature and sprays potassium acetate when it gets cold enough for ice to form. There's also a traffic monitoring system, which detects the speed and volume of cars on the span. If there's an accident that blocks the roadway, information can be relayed to the Transportation Dept.'s central command so drivers approaching the bridge can be alerted or rerouted...

But there are big changes ahead. This bridge has a wired sensor network. The next generation will be wireless. There's even talk about applying sensors to surfaces in the form of a paint-like substance--so it works like human skin. How will thousands or millions of sensors be powered? One possible answer is harvesting the vibrations of the bridges as an energy source. The sensors in the current bridge added less than 1 percent to the total cost.

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