The wake-up call came last week from Minneapolis. And as is too often the case, it was delivered in the form of a life-ending tragedy.
It appears, however, that this tragedy will not be on the scale that had been initially feared. On Saturday morning, the official death toll remained at five, and as the search through the rubble of the Interstate 35-W bridge over the Mississippi River continued, only eight people were missing. Given the number of vehicles on that bridge when it collapsed during the Wednesday evening rush hour, that is indeed miraculous.
The disaster has sent the nation into a flurry of worry and attention to the condition of highway bridges, and entire public infrastructure in general. The bridge that failed catastrophically was on a federal list of structurally deficient spans, one of an eye-opening 73,764 bridges across the country that are not up to grade. An additional 90,226 bridges are described as functionally obsolete. The fact that bridge failures such as this are rare makes it obvious that things arenít as bad as these numbers can make it seem, because these are broad categories that cover a wide range of shortcomings. But even so, itís bad enough.
More than 2,100 Texas bridges were classified under the same structurally deficient rating given to the bridge that collapsed in Minnesota, according to the 2006 report by the Texas Department of Transportation. Another 7,800 were deemed functionally obsolete, meaning they were not designed to handle the current traffic demand.
Texas officials have insisted that all of the stateís approximately 50,000 bridges are completely safe, but a report by the U.S. Department of Transportationís inspector general suggested that many of those bridges are carrying more weight than they should. Thatís a situation that could aggravate any structural weaknesses.
Most most worrisome situations are the original Interstate highway bridges, built in the 1950s and 1960s to much less demanding standards at a time when congestion was minimal and the weights put on them were considerably less. In the years since, construction methods and materials have improved, and engineers have taken into account rapidly increasing traffic loads. But these 50- and 60-year-old structures remain the backbone of Americaís highway transportation system, and the risk of more of them failing in such a horrible manner grows each year.
Time marches on, and the wake-up call from Minneapolis tells us that the bill is coming due. The American Society of Civil Engineers estimates Americans will need to invest $9.4 million a year for the next 20 years to eliminate all the deficiencies. Thatís an immense amount of money, but ignoring the maintainance needs of our infrastructure is a deadly risk.