This bridge, which has been restored, is one of the most important historic bridges in the country. This bridge was originally on a B&O mainline, but was moved way back in 1887 to an industrial spur off of the mainline, which allowed this bridge to remain rather than be demolished and replaced with the more familiar massive-member railroad truss bridges. The bridge was built 1869, placing it among the oldest metal bridges in the country. Wendel Bollman, a noted bridge engineer, was responsible for designing this bridge. His unusual truss configuration, known as the Bollman truss, is a very distinctive design that features diagonals that span varying lengths from top to bottom chord. Most diagonals originate from the endpost. As such, one might imagine how the diagonals function in a manner similar to a cable-stayed bridge. In the truss, all compression members on the bridge (top chord, end post, and verticals) are made of cast iron. All tension members (diagonals, bottom chord) are made of wrought iron. The connection of the diagonals to the top of the end post is enclosed in a protective wooden enclosure. Bollman's design was the first metal truss bridge design to be used in any notable quantity by the railroads, and is thus significant in the development of the metal truss bridge. However, today, this bridge is the last remaining example of the Bollman truss, and thus has unparalleled historic value. The bridge was rehabilitated in 1983 and 2000.
Be sure to read the National Historic Landmark nomination for this bridge which includes the most extensive and complete history and description of the bridge available. It is much more extensive than even the HAER narrative.
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