River Road Bridge Substructure

Information and Findings From New Jersey's Historic Bridge Inventory

 Summary

The bridge has been rated not eligible by the NJT Historic Bridge Survey due to the undistinguished nature of the timber stringer superstructure which was built in 1949 when the vertical clearance was raised. What is of technological merit are two pairs of well-detailed cast iron bents composed of hexagonal columns and cross bracing. They appear to be monolithic castings. Although the bridge itself is insignificant, the bents are exceptionally unusual and significant structural elements.

Physical Description

The single-lane 81'-long bridge is three span resting on stone abutments and impressive monolithic cast-iron column bents on ashlar plinths. The center span of the superstructure, placed in 1949 has rolled steel I beam fascia stringers and interior wood stringers. Two rolled section floor beams are hung from the fascia stringers. The shorter end spans are exclusively wood stringers. The superstructure has been raised from its original elevation and the stone abutments and pier bases have concrete caps. The bridge has a timber deck, timber curbing, and wood railings. The handsome cast-iron column bents consist of two sets of paired columns with lateral and diagonal cross bracing. The columns are octagonal in cross section and are tapered and finished with pedestals and capitals. The lateral and diagonal bracing are x-shaped in cross section, except for the top and bottom laterals which are t-shaped. The bents appear to be monolithic, one-piece castings. The number "10" is cast in the eastern piers, and the number "12" is cast in the western piers.

Historical and Technological Significance

Although the bridge has been altered by the 1949 rebuilding of the superstructure, the two castiron columns bents are exceptionally significant examples of a very rare type of bridge structural element. According to Central Railroad of New Jersey records, the overpass bridge was initially constructed in 1886, and the superstructure was raised in 1949 with the original bents remaining. The railroad right-of-way was originally developed in 1848 by the Somerville and Easton Railroad and later taken over by the Central Railroad of New Jersey. The cast-iron bents appear to be monolithic castings, and they are highly crafted. No other bents of this type have been identified to date. Much of the early success and eventual general acceptance of metal bridges and related structural elements is directly attributable to the skill of foundry men. These bents stand as a record of their knowledge and ability. Cast iron came into increasing use as a structural element in the early-19th century but was replaced with other materials such as wrought-iron, steel, and concrete by the end of the century. The NJT Bridge Survey incorrectly identified the piers as "Phoenix Columns," which were always segmental, riveted, wrought-iron structural elements patented and manufactured by the Phoenix Bridge Company of Phoenixville, Pennsylvania. In the 1880s the Phoenix Bridge Company produced many other types of wrought-iron, cast-iron and steel structural elements. The NJT Bridge Survey recommends a status of not eligible for the bridge; because of the rarity of the cast-iron bents, A. G. Lichtenstein recommends a status of eligible.

Boundary Description and Justification

The boundary is limited to the bents. The other portions of the bridge are not significant.

Sources

DeLeuw, Cather, and Company. New Jersey Transit Historic Bridge Survey, 1991. New Jersey Department of Transportation. Bridge Plans, 1949.

Bridge Considered Historic By Survey: Yes