Mississippi Bridge Cracks Hidden by Welds Prompt Nationwide NDT Push

During a 2021 inspection of the Hernando de Soto Bridge, one of its main steel tension ties fractured almost entirely due to hydrogen assisted cracks from a pre opening weld repair; ultrasonic testing later found 12 more hidden cracks in other butt welds that visual inspection had missed. The findings prompted FHWA to require broader non destructive testing of older fracture critical T-1 steel members, echoing a 2011 incident on the Sherman Minton Bridge and underscoring that surface checks can miss hidden flaws.