Heavily Traveled and Structurally Deficient
Posted on Friday, Aug 17, 2007

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.