Few examples of the Groton Bridge Company, an important New York bridge builder, remain in New Jersey. As such, this bridge is a noteworthy surviving example. Typical of Groton Bridge Company pony trusses, plaques are mounted on top of the top chord.
Aesthetically, this is a nice bridge because it has attractive lattice railings with a decorative motif in the center of each lattice panel, and also the design of the bridge offers relatively tall trusses for a pony, making the bridge look more impressive.
Information and Findings From New Jersey's Historic Bridge Inventory
Discussion of Bridge
Summary: The 5-panel Pratt pony truss pin-connected bridge bears on random ashlar abutments. The bottom chord is composed of stamped eye bars. 1991 alterations included welded reinforcing plates on floorbeams and a new flooring system with a glulam deck. Otherwise the trusses are well preserved. Lattice web railings with center medallions remain. The span is significant as a good example of its type and as an example of the work of the Groton Bridge Co., a NY fabricator not well represented in the state.
Bibliography: Thurber, Pamela. "The Groton Iron Bridge Company." Historic Ithica and Tompkins County Newsletter. Fall, 1983.
Physical Description: The 5-panel full hip pin-connected pony truss bridge is supported on ashlar abutments. It has some small reinforcing elements added at the panel points, but most of the original fabric survives, including the lattice railing with decorative bosses on the bridge and atop the low stone walls of the approaches. The top chord and inclined end posts are composed of toe-out channels with a top web plate and battens on the bottoms. The verticals are back-to-back angles with a laced web. The connection of the verticals to the panel points is by a plate riveted, bolted, or welded to the angles. Diagonals and the bottom chord are made up of stamped, roundheaded eye bars while the counters are loop forged bar stock. The rolled I-section floor beams are hung from the bottom panel points by u-hangers. The bridge exhibits no unusual construction details. Modifications to the original design include outriggers connected by welds and splice plates to the floor beams and top chord and a wood laminated deck added in 1991.
Historical and Technological Significance: The pin-connected Pratt pony truss bridge, built in 1896, is a well-preserved example of a historically important bridge type. One of over 10 examples of the bridge type in Hunterdon County, which is distinguished with having more 19th-century truss bridges than any other county in the state, this span is historically noteworthy because it is a documented example of the work of the Groton Bridge Company of Groton, New York. It is one of less than six documented examples of their work in the state. Groton is located on a spur of the Southern Central Railroad that was opened in 1869 linking the small town near Ithica with routes to Canada and Pennsylvania coal region. In 1877, two small agriculture-related businesses, the Groton Iron Works, a blacksmith shop, and the Groton Separator Works, a manufacturer of farm implements, merged in 1877 to form the Groton Bridge Company. The firm was established to take advantage of the rapidly increasing metal truss bridge market that was developing as county after county set about improving and upgrading their roads. The company grew and prospered, becoming one of the largest employers in the community and building bridges in at least 27 states. Between 1877 and 1887, the firm built mostly small pony truss bridges in upstate New York. In 1887 the operation was expanded and the product line increased to include larger bridges. It was during this expanded phase of the company's operations that the bridge in Glen Gardner was built and finished with the distinctive demilune plaque atop each top chord. In 1900 the company was absorbed into the new American Bridge Company. The company continued its operations until the 1920s. It also produced structural steel. The history of the Groton Bridge and Manufacturing Company is reflective of the era during the late-19th century when a host of small companies recognized the economic advantage of designing and manufacturing metal truss bridges as the nation embarked on its most ambitious road improvement campaigns. The era of individual companies, represented regionally and/or nationally by local sales people, was brought to a close in 1900 with incorporation of J.P. Morgan & Company's American Bridge Company, a conglomerate made up of 24 companies that represented half the nation's bridge fabricating capacity. Some plants were closed, and others, like Groton's works, continued in operation.
Boundary Description and Justification: The bridge is evaluated as individually distinguished. Its setting does not appear to have historic district potential. Thus, the boundary is limited to the substructure and superstructure of the span itself.
Discussion of Surrounding Area
The bridge carries one lane of traffic over a minor stream. It is located in a wooded village setting of modified 19th and 20th century houses.
Bridge Considered Historic By Survey: Yes
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