Survey number HAER PA-497
Building/structure dates: 1908 initial construction
FROM THE 1996-2001 PENNSYLVANIA HISTORIC BRIDGE SURVEY: The Mulberry Street viaduct carries 2 lanes of traffic and 2 sidewalks over city streets, SR 230 (Cameron St.) and 9 tracks of Conrail's and Amtrak's railyards and lines in downtown Harrisburg. The viaduct connects midtown Harrisburg to Mount Pleasant (Allison Hill). The east end of the bridge is contiguous to the Mount Pleasant Historic District (listed 1/11/85), an area of predominantly late 19th and early 20th century industrial, commercial, and industrial architecture with a period of significance of 1800 to 1940. The viaduct terminates at its northwestern end adjacent to the Pennsylvania RR Station (listed 6/11/75).
The 20-span, 1598'-long, four-ribbed, closed spandrel arch bridge built 1907-1909 has distinctive piers that are ornamented in the Classical style with pilasters and entablature. In 1957, the bridge deck was replaced and the original 3 high rail concrete railings were replaced with aluminum railings. The bridge is an early and innovative application of reinforced concrete arch bridge technology in the state. It ranks as one of the two oldest of nine ribbed, closed spandrel arch bridges identified. The bridge is considered the first major reinforced concrete highway bridge in Harrisburg. It was built to replace a metal truss viaduct over the Pennsylvania RR's yard. The bridge is a historically and technologically distinguished example of the ribbed, closed spandrel arch bridge type/design.
DISCREPANCY NOTE: PENNDOT lists it as having 20 spans. I counted and there are clearly 19 just as HAER indicated