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Wassum Bridge

Wassum Bridge

Primary Photographer(s): Nathan Holth

Bridge Documented: August 1, 2010

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Key Facts

Facility Carried / Feature Intersected
Watson Road (TR-439) Over North Branch Slippery Rock Creek
Rural: Butler County, Pennsylvania: United States
Construction Date and Builder / Engineer
By Builder/Contractor: Penn Bridge Company of Beaver Falls, Pennsylvania

Technical Facts

Rehabilitation Date
Not Available or Not Applicable
Main Span Length
36 Feet (11 Meters)
Structure Length
38 Feet (11.6 Meters)
Roadway Width
15.7 Feet (4.79 Meters)
1 Main Span(s)
NBI Number

Historic Significance Rating (HSR)
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Bridge Documentation

View Archived National Bridge Inventory Report - Has Additional Details and Evaluation

This bridge is a short and traditionally composed example of an early 20th Century pony truss bridge. The trusses appear to retain excellent historic integrity, although the builder plaque has been damaged and a portion is missing. The bridge has an unusual detail in that the bottom chord of the bridge is a specially designed built-up beam that extends up above the deck to form a curb for the bridge. This hybrid design is not singled out by the Historic Bridge Inventory as a noteworthy detail, and is instead described as "common technology." While HistoricBridges.org has documented another example of a bridge with this detail in Pennsylvania, this detail, which demonstrates the ingenuity of period engineers as they sought to improve bridges while also making sure they made efficient use of materials, appears to be rare and thus should be considered significant.

Information and Findings From Pennsylvania's Historic Bridge Inventory

Discussion of Bridge

The riveted, 40'-long and 15' wide Pratt pony truss bridge is supported on ashlar abutments with wingwalls. It was fabricated by the Penn Bridge Co. ca. 1910 (commissioners on plaque elected in 1908). The trusses are traditionally composed, and the rolled section floorbeams are riveted to the vertical members using triangular shaped plates. The fascia stringers are built up to form curbs; the rest are rolled I beam sections. The design seems to be an attempt at providing a stiffer, stronger bridge. The other truss members are traditionally composed. There are welded repairs to the inclined endposts. The bridge is an example of what by ca. 1910 was common technology, and neither the bridge nor its setting are historically or technologically significant.

Discussion of Surrounding Area

The bridge carries 1 lane of an unimproved township road over a stream in a sparsely developed, wooded setting with scattered, undistinguished 20th century residences. The area does not have rural historic district potential.

Bridge Considered Historic By Survey: No


Photo Galleries and Videos: Wassum Bridge

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Maps and Links: Wassum Bridge

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