PITTSBURGH—The bridge that collapsed in Pittsburgh last week showed deterioration during a September inspection that was not bad enough to require its closure, the Pennsylvania Department of Transportation said Monday. The agency will not release the full inspection report, PennDOT spokesperson Alexis Campbell said, citing state and federal laws and the ongoing investigation into the Friday morning failure of the Forbes Avenue bridge over Fern Hollow Creek in Frick Park. Campbell did provide some details about the inspection four months ago, including that there has been a 26-ton posted weight limit on the bridge since 2014. As with previous inspections, the Sept. 29 examination rated the steel K-frame bridge a four on a scale from zero to nine, which is deemed a poor rating. “This bridge’s design relies on the quality of frame elements alone without any back-up support (known as redundancy) and reports show deterioration that did not warrant …