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NOVA News Minutes Bridge Band-Aids (running time 01:33) Transcript August 15, 2003 NARRATOR: It's just one bridge across one river. But as shown on PBS's NOVA, it took four years to build at a cost of $90 million dollars. According to the American Society of Civil Engineers, more than a quarter of the bridges in the U.S. are deficient. TONY NANNI (University of Missouri-Rolla): If you can think of a bridge as almost a human body, the human body ages, so does the infrastructure. The bridge that we're looking at today is over 60 years old, and we are asking this bridge to carry heavier loads. NARRATOR: But instead of building new bridges, engineer Tony Nanni wants to reinforce existing bridges with sheets of carbon composites—the same materials used in spacecraft. TONY NANNI (University of Missouri-Rolla): These materials are much stronger then conventional materials. They are light, they are strong, and they are stiff. NARRATOR: It's up to ten times stronger than steel. And applying it can be as easy as wallpapering your home. Nanni took a bridge that was slated for demolition and reinforced one span with composite sheets. He tested that and a control span with hydraulic jacks. It took 25 percent more pressure for the reinforced span to fail. One issue is that, for now, carbon composites are significantly more expensive than standard materials. But Nanni says the cost is offset by how fast composite sheets can be installed. When an oversize truck broke a girder on this highway bridge, a crew using Nanni's bridge Band-Aids fixed it in just 12 hours. Traditional methods would have required days or weeks of labor... and detours. I'm Brad Kloza. Build A Bridge | Resources | Guide | Transcript | Bridge Home Editor's Picks | Previous Sites | Join Us/E-mail | TV/Web Schedule | About NOVA Watch NOVAs online | Teachers | Site Map | Shop | Search | To Print PBS Online | NOVA Online | WGBH © | Updated August 2003 |