A crack that closed the Delaware River Bridge between Philadelphia and New Jersey last January has prompted the Pennsylvania Department of Transportation to plan repairs to 13 other bridges across the state. The crack in welding material, which created a 2-inch gap in a major truss, was so serious that officials thought they might have to permanently close the span owned by the Pennsylvania and New Jersey turnpikes. As a result of that problem, PennDOT looked for similar issues in other bridges; the repairs will involve drilling out areas where welding occurred to fill improperly drilled holes, called plug welding,...