South Clinton Avenue Bridge
Photo taken by Historic American Engineering Record
BH Photo #142390
SETTING / CONTEXT The bridge is located in downtown Trenton and carries a 2-lane street over the main electrified line of Amtrak's Northeast Corridor. The depressed right-of-way has a brownstone ashlar retaining wall. The west end of the bridge rests on the 1869 stone arch across Assunpink Creek. The bridge is in full sight of the Pennsylvania Railroad's Trenton passenger terminal (now NJT). Surrounding area has been cleared and/or redeveloped.
SUMMARY The heavily skewed pin-connected double-intersection Pratt thru truss is a rare example of an unusual type. It stands in well preserved condition although a modern aluminum curb barrier covers the lower portion of the truss. The bridge was rehabilitated in 1981. In addition to its engineering significance, it is part of the historic transportation networks in Trenton, a town that grew because of and in response to transportation systems.
INFORMATION Bibliography: Sanborn Insurance Maps, 1890-1923. A. G. Lichtenstein Project File.
Physical Description: The 10 panel pin-connected double intersection Pratt skewed thru truss bridge is a half hip with the inclined end post and top chord composed of steel channels and plates. Deep trusses designed for heavy live loads, the bridge has upper and lower lattice sway bracing. Laced channels make up the verticals, and the diagonals are bar stock while the counters are rods. The bridge was strengthened in 1981 by post tensioning the trusses with cables. New stringers and wearing surface were also installed as was an aluminum safety shape barrier, attached to the flooring system, not the trusses. The remedial work is not intrusive. The bridge is supported on ashlar abutments that predate the present span. The northeast side bearings rest on the 1869 stone arch that crosses Assunpink Creek. Historical and Technological Significance: The well-preserved skewed Pratt thru truss bridge was built in 1891 (fabricator unknown) after plans developed by the Pennsylvania Railroad's Office of the Chief Engineer (William H. Brown). It stands as a good example of late-19th century pin-connected metal truss technology and a truss type (double intersection Pratt or Whipple) that is not common. The truss type as well as its depth reflect the anticipated loading the bridge needed to support. Using the 1869 2-span stone arch at its northeast end as its seat, the truss bridge and the stone arch work in tandem to carry a local street over four tracks of the former Pennsylvania Railroad (Amtrak's main electrified line) and the channeled creek the tracks parallel. The pair represent the two dominant bridge technologies of the 19th century and as such are an important record of 19th-century technology.
The truss bridge was apparently installed when the Pennsylvania Railroad four-tracked its main line through Trenton. The right-of-way was established in 1862 when the Camden & Amboy Railroad (absorbed by the Pennsylvania system in 1871) realigned and thus straightened its route through the city. At that time the station was moved to S. Clinton Street. What type of structures serviced the crossing of the tracks and creek prior to 1869 are not known. Assunpink Creek originally crossed under the tracks between the vehicular bridge and the station. The creek was realigned in its present configuration prior to 1891.
A. G. Lichtenstein and Associates prepared bridge rehabilitation plans for NJDOT in 1979, and the work was done in 1981. The aluminum safety shape protects the lower portion of the trusses and the pin connections (not visible but still in place). Any replacement of original/early members was done in kind.
Boundary Description and Justification: The bridge is individually eligible, as is the contiguous stone arch bridge (1100052) that forms the north abutment of this bridge. The two bridges together form one resource that works in tandem to cross the creek and the railroad tracks that parallel the creek. The stone bridge was modified to accommodate the erection of the metal truss bridge. The metal truss bridge was built as part of the Pennsylvania Railroad's improvements of the station and right-of-way, but the setting has been changed greatly with the removal of the historic stations and surrounding buildings. thus, the historic boundary is limited to the substructure and superstructure of the metal truss and stone arch bridges.