What does poor rating for collapsed bridge mean for others?

A 50-year-old bridge that collapsed in Pittsburgh had been rated as poor on a recent inspection report, but transportation officials and engineering experts cautioned that doesn’t necessarily signal imminent danger for the thousands of other U.S. bridges with the same designation.

Investigators from the National Transportation Safety Board and the Federal Highway Administration have been combing through rubble from the collapse early Friday of the Forbes Avenue Bridge, looking for what caused it.

President Joe Biden, who was in Pittsburgh on Friday to promote a $1 trillion infrastructure law, said it was miraculous that there were no fatalities and that only a few people were injured.

City officials said the most recent inspection report of the city-owned steel bridge from September wasn't available Friday. But a September 2019 inspection showed the bridge's deck and superstructure were in what inspectors said was poor condition.

Infrastructure spending advocates noted there are thousands of bridges across the country with the same poor designation but few instances of collapse. Many said funding has not kept up with the need for repairs and replacements.

HOW DO BRIDGE INSPECTIONS WORK?

The Federal Highway Administration's bridge inspection program was developed after the 1967 Silver Bridge collapse in West Virginia, which killed 46 people. It has expanded over the years to include state- and municipally owned bridges, not just those in the federal highway system, and to include rules for underwater inspections and regulations for qualifications of inspectors.

Generally, bridges are inspected every two years, with some older or lower-rated bridges inspected more often.

The municipal or state entities that own and maintain the bridges submit those inspection reports...