Fallston Bridge

Fallston Bridge

The Fallston Bridge is an ornate wrought and cast iron structure that traverses the Beaver River between the boroughs of New Brighton and Fallston, Pennsylvania and is the oldest bridge in Beaver County. The Penn Bridge Company of Beaver Falls in 1884 replaced the original Fallston Bridge erected by the Fallston Bridge Company in 1936.  The initial bridge was a tolled, wooden structure that was demolished by a major storm on February 7, 1884 and swept away by the resultant flood.

 

 

The 406-foot long vehicular bridge was constructed as a two-span pin connected Whipple through truss.  The bridge has a 20-foot wide-open grated deck for a driving surface.  The bridge also has both diagonal tension members and vertical compression members between the upper and lower chords, with the diagonals sloped toward the center. 

Squire Whipple (1804–1888) patented the Whipple through truss in 1847.  Whipple was a civil engineer, inventor, theoretician, and was considered the father of scientific bridge building as he developed the first mathematically based rules for bridge construction. Squire published the first significant formula to calculate stresses in the articulated truss.

The Whipple truss is a stronger version of the Pratt truss and is known as the "Double-intersection Pratt" because the diagonal tension members cross two panels, while those on the Pratt cross only one. They were usually built where the span required was longer than was practical with a Pratt truss. Thomas and Caleb Pratt designed the Pratt truss in 1844.

 

The Fallston Bridge is a rare instance of a Whipple truss highway bridge since this design was primarily used for railroad bridges and used sparingly for roads.  Only a few wrought iron examples survive today. Truss bridges are one of the oldest types of modern bridges. Renovations occurred in 1981 and 2005. The bridge is eligible for the National Register of Historic Places.