An Inquirer analysis of federal transportation data identified 57 heavily traveled bridges in our region that are designated “structurally deficient” with a rating the same or lower than the rating of the Interstate 35W bridge in Minnesota that collapsed Aug. 1.
“Structurally deficient” does not mean a bridge is unsafe. It signifies that the structure received a rating of “poor” or worse on one of its three primary components: the deck, superstructure or substructure. Ratings can range from 0 (failed) to 9 (excellent).
A separate sufficiency rating is a 0 to 100 calculation based on many factors. A bridge’s safety accounts for 55 percent of the equation. Other factors include the ability to meet traffic conditions and how essential the bridge is for public use. A score below 50 entitles a structure for federal replacement funding.
A “structurally deficient” bridge is inspected at least once every two years. Bridges with weight restrictions are inspected once a year. A structure that fails a safety inspection will be closed until it can be rehabilitated or replaced.