The following coppied from 1987 NJ state bridge report.
SUMMARY The 4-panel pin-connected Pratt half hip pony truss, moved to this location in 1930, is one of the two examples in Mercer County. Two verticals on the south end of upstream side are replacements, but the others are composed of an unusual rolled T section, a detailed unique to Wrought Iron Bridge Co. spans. The bridge is well preserved and is supported at one end on ashlar abutments from the previous span. The bridge is eligible because it is a documented early example of a WIBC span.
INFORMATION Bibliography: Mercer County Engineer's Office: Transfer File 672.7. Waddell, J.A.L. Bridge Engineering. 1925.
PHYSICAL DESCRIPTION The 15'-wide 4-panel pin-connected half hip Pratt pony truss with a plank deck survives with few modifications to its original design. Its top cord, inclined end posts are composed of plates and channels riveted to make a box member. The most distinctive feature of the bridge are the rolled or cast "beaded Tee" sections used for the original laced verticals. The heavier angle verticals with lattice and batten plates at the southwest corner appear to be not recent replacements that are consistent in style and type with the original design of the bridge. The diagonals are bars with loop forged eyes and sleeve nuts in the middle panels where the load is the greatest. Counters are lighter rods with loop forged eyes. A gusset plate riveted to the bottom on the verticals serves as the connection at the pin. The rolled section floor beams, which appear to the originals, are connected by typical U-bolts hangers. Strengthening knee braces, or outriggers, are bolted with regular bolts to the floor beam but riveted at their upper connection. A steel curb and original/early pipe railing provide impact protection for the truss on the downstream side, but modern beam guide rail has been welded to the road side on the upstream truss. The modern guide rail is the most drastic modification to the span.
HISTORICAL AND TECHNOLOGICAL SIGNIFICANCE The date of construction of the well-preserved Pratt half hip pony truss is not documented, it is known to have been designed and fabricated by the Wrought Iron Bridge Company of Canton, Ohio prior to 1885. Originally erected over Jacobs Creek on the Washington Crossing-Pennington Road in Hopewell Township (#214.4), it was dismantled truss by truss, and moved to Groveville-Allentown Road in 1930 (Mercer County Engineer's Transfer File 672.7). Reusing of pony truss bridges was apparently a common practice in Mercer County. Other documented examples of a similar relocation is Iron Bridge Road in Hamilton Township. Despite the relocation, the pin-connected truss survives in a remarkably complete state of preservation with no readily visible welded repairs. Outriggers or knee braces have been added at the panel points to brace the top chord against buckling outward, a modification frequently made to pony trusses.
The most distinctive feature of the bridge are the seldom-seen rolled or cast "beaded Tee" sections employed in the vertical members. As explained in its 1885 catalog, the "beaded Tee" was a Wrought Iron Bridge Company patented detail designed to be used in "the wide Lattice Post ... to give perfect lateral bracing to the girders, and is much neater in appearance than the cross or side braces formerly used for this purpose." The same patented section shape is used on the Devereux Road bridge over the East Branch of Brandywine Creek in Chester County Pennsylvania (Chester County #138). That bridge was fabricated by the Wrought Iron Bridge Company and has a patent date of 1877, according to Chester County records.