This bridge is an extremely old and rare example of a pin-connected Warren pony truss bridge. The Pratt was vastly more common for a pin-connected pony truss, making this bridge rare. The bridge has added significance as a rare example of a skewed pin-connected truss bridge. The bridge is skewed by 20 degrees. The bridge has several unusual details. The tension diagonal members are built-up with a corrugated design, which is an uncommon type of built-up beam, although it is more common with bridges like this one which are associated with a railroad. It is possible, the railroads did it to provide additional strength against bending of the two bars, which might have normally been left separated. Railroad bridges experience different forces than highway bridges, and so the thinking of railroad engineers was often different, even if the railroads were designing bridges for highway use. The dimensions of the top chord are larger than that of the end posts, which is very odd and gives the bridge a somewhat top-heavy appearance. The bridge has a very nice set of roller bearing nests which were surprisingly clean of debris during the field visit to this bridge.
The bridge retains good historic integrity, with all major alterations being reversible alterations which were added to the bridge. The vertical members appear to have been post-tensioned, but the original bars remain in place. Also, small outriggers were added to the bridge. Perhaps another blessing of a bridge being designed by the railroads, the bridge has extremely massive members for an 1879 bridge, something that has undoubtedly allowed this bridge to remain even today in good condition and continuing to carry vehicular traffic.
Information and Findings From Pennsylvania's Historic Bridge Inventory
Discussion of Bridge
The one-span, 89'-long, pin-connected, wrought-iron Warren pony truss bridge is supported on stone abutments. The bridge has closely spaced wood floorbeams supporting a wood deck. The bridge was built in 1879 for the Northern Central Railway, a line operated by the Pennsylvania Railroad between Baltimore and Sunbury, PA. It was relocated over the PRR Trenton Cut-off ca. 1902-04. The bridge is a historically and technologically significant, rare and complete example of a pin-connected Warren truss bridge. It documents one of the many variations of iron truss bridges developed and used by the railroads from the 1860s to the 1880s. It is representative of the innovation and diversity that characterized metal truss bridge development during its golden age. In addition to its individual significance, the bridge crosses over a rail line that has historic significance and has been determined eligible by PHMC. It is contributing to the rail line.
Discussion of Surrounding Area
The bridge carries a 2 lane road over 1 track of Conrail. The line is the former Trenton Cut-off of the Pennsylvania RR. The line was constructed in 1902-04 as a bypass of Philadelphia for freight headed to and from New York. The Trenton Cut-off has been determined eligible by PHMC (9/14/93). The bridge is in a suburban setting of post-World War II residential and commercial development.
Bridge Considered Historic By Survey: Yes
Original / Full Size Photos
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Crossing The Bridge
Full Motion Video
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