Audit faults ratings, postings on U.S. bridges

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An audit of structurally deficient National Highway System bridges showed that Rhode Island had the highest percentage, but Delaware and California led the country in average daily vehicle traffic on deficient bridges. In Delaware and California, more than 50,000 vehicles cross deficient bridges daily.

The recent report by the Office of Inspector General audited state transportation department efforts in calculating load ratings and posting weight limits on structurally deficient NHS bridges, as well as the Federal Highway Administration’s oversight of these state actions.

The FHWA’s 2003 National Bridge Inventory identified 592,000 highway bridges total. The inventory’s 6,491 structurally deficient NHS bridges are spread across the 50 states, Puerto Rico and the District of Columbia and were classified as such because they had major problems such as deterioration or cracks. “The FHWA can do more to oversee states’ actions in inspecting bridges, calculating load limits and posting maximum weight limits,” many of which are inaccurate or outdated, the audit stated.

Auditors concluded that bridge inspections in Massachusetts, New York and Texas were adequate and used the states as a sample. Still, they found errors in such things as the calculation of load ratings or the posting of maximum weight limits for 33 of the 43 bridges reviewed. Some bridges lacked the necessary postings altogether. On at least 12 of the 33 bridges, errors allowed vehicles to cross that were heavier than the bridge’s maximum weight limit.

In the wake of the 2005 Gulf Coast hurricanes, several states increased or suspended the maximum legal weight of tractor-trailers across bridges so the trucks could carry more emergency supplies.

A bridge in South Strabane Township, Pa., south of Pittsburgh, partially collapsed in December, dropping 125 tons of debris onto eastbound I-70. It and a neighboring bridge were demolished and are being replaced, with delays expected through summer.