View of the Union Bridge from the Point in downtown Pittsburgh, circa 1905. The Union Bridge (1874-1907), originally built as a covered toll bridge of wood construction. The bridge was damaged in the Big Flood of 1907 and demolished because of its low clearance over the Allegheny River. It was replaced by the steel-framed Manchester Bridge, which served from 1913 through 1969, and later by the Fort Duquesne Bridge, which opened for traffic on October 17, 1969.