Safe bridges

Friday, August 10, 2007

The bridge collapse in Minneapolis and, just a few days before, the rupture of a steam line in New York City have made us focus on the reality that much of what we assume will work might, without notice, stop working.

But the fact remains that most of the nation's infrastructure is still working. Even grim reports that most bridges in the U.S. -- several hundred of them in Missouri -- are "structurally deficient" do not accurately inform the public. According to structural engineers, the "structurally deficient" label is given to any bridge that has even one component that is below engineering standards. Does this mean the bridge is ready to fall down? No. It means there are repairs needed.

Area residents will remember the old bridge across the Mississippi River at Cape Girardeau that was replaced just a few years ago. The dangerously narrow steel-girder bridge was on its last leg. While piers for the new bridge were being poured, thousands of tons of concrete had to be driven across the old bridge to the Illinois side of the new-bridge project. The Missouri Department of Transportation carefully considered whether the old bridge could stand the strain of having hundreds of loads of concrete going across the old bridge and even came up with a backup plan to take the concrete across on barges.

But the old bridge, despite its age and perceived danger, held up -- even though its structural deficiencies were numerous.

Most infrastructure failers like the bridge collapse in Minneapolis occur for a reason. Engineers now wonder if trucks filled with heavy loads of gravel that were parked on the bridge while it was being resurfaced might have played a role in the disaster.

Not to make light of the need for serious attention to the safety of our bridges and other infrastructure, the fact is that our chances of being involved in such a failure are slim.

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