This attractive swing bridge also includes pony truss approach spans.
Information and Findings From New Jersey's Historic Bridge Inventory
The rim bearing swing span bridge supported on an ashlar substructure is composed of a hybrid pinned/riveted Warren thru truss main span with built-up floorbeams and Warren pony truss approach spans. The electrical system was replaced in 1984. The swing span reflects the state of design knowledge of the time which makes the span an important example of the evolution of movable bridge technology. It is one of four thru truss swing spans in Essex County. All are significant.
The bridge carries a 2-lane collector road and sidewalks over a major river in a commercial area with structures dating from the 1950s to the present. The bridge is known as the Avondale Bridge.
The rim bearing swing-span bridge is composed of a hybrid pin-connected and riveted double-intersection Warren through truss swing-span and two Warren with verticals pony truss approach spans. The bridge measures 364' in length and carries a 27' roadway and 2 cantilevered sidewalks. The fish-belly shaped top chords are of built-up back-to-back channels connected by lacing at the bottom and a cover plate for most of the span except at the center tower where it is composed of pin-connected stamped eye bars. The same arrangement is also used on the 1906 Gregory Ave. bridge in Passaic County (1600002). The arrangement permits the Warren trusses to act as simply supported span when the bridge is taking live loads. An unusual detail is the transition panel between the pinconnected and rivet-connected portions of the top chords where it is composed of eye bars built up with rivet-connected angles connected by lacing. The diagonals and the lower chords are built up with two pairs of back-to-back angles connected by lacing. They have been strengthened with additional material bolted to the webs. The vertical members are built-up with two pairs of back-to-back angles separated by lacing. The sidewalks are flanked by modern 3-rail metal railings. The power source and controls for the bridge were altered in 1984 when new motors, generators, and controls were installed. The equipment house was moved to its present mid-span location at that time. The gearing remains the same or inkind replacements. Other work done in 1984 includes repairs to the steel superstructure, rest piers, abutments, and fenders and replacement of the stringers and deck. The truss diagonal members were repaired. The gate houses and operators house, and overhead generating room, including supporting members, also date to the 1984 rehabilitation.
Historical and Technological Significance
The 1904-05 swing-span bridge, designed by the Bergen and Essex county engineers, is historically significant because it is one of fewer than ten spans in the state constructed by the New Jersey Bridge Company, a New Jersey bridge manufacturer who successfully marketed bridges nationally. This is one of if not the largest bridge in New Jersey that they erected. The bridge is technologically significant because its construction details reflect the state of design knowledge at that time which could only account for simply supported spans for live load considerations. The pin-connected top chords are for the tension-only, double cantilever configuration the span assumes during operation (when it is not supported at the toe end by the bearings on the rest piers). The rivet-connected Warren trusses are for live-load configurations. The presence of the not-rigid eye bars would not permit transfer of liveload stresses between spans. (Criteria C). Although the bridge and operating machinery have been altered, the historical and technical significance of the span remain, and the bridge maintains integrity of function. The New Jersey Bridge Company of Manasquan, New Jersey, was established in 1890 by two men from Canton, Ohio, Mr. Wyckoop and Mr. Braly. The company built many steel bridges in New Jersey, and it employed 15 to 20 draftsmen and up to 100 construction workers. Their bridges have been identified from Maine to Michigan. Financial difficulties incurred due to problems on a bridge in Portland, Maine, caused the failure of the firm in 1907. The F. W. Stillman Company acted as the general contractors for the bridge construction.
Boundary Description and Justification
The bridge has been evaluated as individually significant. The boundary is thus limited to the span itself and includes the superstructure as well as the substructure.
Essex County Engineers Office. (Plans) Essex County Board of Chosen Freeholders Minutes. Manasquan, New Jersey, compiled by Townsfolk for the Diamond Jubilee under the sponsorship of the Manasquan Chamber of Commerce, 1962.
Bridge Considered Historic By Survey: Yes
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