Thwarting Disaster: Bridges That Can Withstand Anything

[Steve]

President Obama has promised the largest investment in infrastructure since the creation of the Interstate Highway System. For America's bridges, it's about damn time: Nature, age, and faulty designs are beginning to take a toll (see above: Minneapolis, 2007). Luckily for commuters and trolls, engineers around the world are figuring out how to build smarter spans that can shrug off disaster. Here are three new approaches.
Challenge: Extreme temps
St. Anthony Falls Bridge, Minneapolis

The new I-35W span has its own nervous system, with 323 sensors. Through harsh winters and steamy summers, gauges will track the expansion and contraction of joints and supports. When temps drop below 32°F, sprayers will automatically coat the road with deicer.
In addition to the sensors embedded in the bridge's roadway, cameras placed both along the road and inside the bridge's hollow concrete box girders track traffic flow and speed and monitor security. All of the data collected is analyzed by engineers from Minnesota’s Department of Transportation and researchers at University of Minnesota’s Traffic Observatory.
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