Iowa looks better than several surrounding states in the latest report on bridges from the Federal Highway Administration. Norm McDonald is director of Bridges and Structures with Iowa’s transportation department. He says on the Interstate and primary bridges, which number 4,148, 14-percent are “deficient or obsolete” and of the 28,823 bridges on secondary roads, about 31-percent are deficient. McDonald says the terms sound alarming, but don’t mean you’re in danger when you drive over a bridge with a low rating. The engineer says “structurally deficient” can be serious but not necessarily, and “functionally obsolete” can mean it simply has poor deck geometry — too narrow for the traffic it carries — and on a seldom traveled highway that won’t have much impact. McDonald says that “obsolete” classification could also mean the bridge simply isn’t built to handle the kind of floods that hit in 1993. McDonald says the D.O.T. has a good effort to identify bridges that are serious safety concerns, and he says those have been replaced. Plus, some preventive maintenance has proved valuable in preventing more costly rebuilding. The last 20 years or so the state’s overlay project has involved removing the top surface of a bridge deck and replacing it, which keeps road salt from corroding the underlying beams. While budget considerations have put a delay into some projects, McDonald says Iowa’s planned ahead better than most neighboring states, and had its priorities in place so urgent jobs could get done and others simply stretched out.
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