PennDOT ordered the emergency closure of the Birmingham Bridge this morning due to an unexplained drop of up to 8 inches in a portion of the span over the Monongahela River. The drop, apparently noticed overnight by a motorist who called 911, occurred on the span linking Fifth Avenue, Uptown, to the South Side. The inbound, or nothbound, lanes were likewise ordered closed, at 8:45 a.m., to allow for a comprehensive inspection of the entire bridge, which really is two independent superstructures. Crews were working to shore up the western edge of the outbound span where the roadway had dropped...