This is an unusual small-scale, lightweight riveted Warren deck truss bridge. It was rehabilitated in 2003.
Information and Findings From DHPA Historic Bridge Survey
Statement of Significance
The northern third of Newton county lay at or below the water table until drained in the late nineteenth and early twentieth centuries. The 1876 state atlas, for example, shows most of the two northwest townships--Lake and McClellan--as swamp. Indeed, the map marks the "original Beaver lake outline" as incorporating the northern half of McClellan and several central- southern sections of Lake townships. One of the few highways that crossed the sloughs by mid- nineteenth-century, today's CR#700N extended from the Illinois border along a ridge at the southern edge of Coon Marsh to the community of Conrad, located just east of the main north- south road to Chicago (now US#41). Extensive efforts to drain the sloughs and lakes succeeded only a little at a time until in the second decade of the twentieth century the Kankakee River itself was substantially dredged and limestone ledges restricting water flow in Illinois blasted from the river bottom. Newton county residents followed the progress of the Kankakee dredging with great interest. For Platt M. Conrad and other Lake township leaders, the interest was material. Conrad had been pressing unsuccessfully for major improvements in a number of township roads until the state Supreme Court in 1909 sides with Conrad and ordered construction. A highway tax levee funded road building and inevitably promoted bridge construction in its wake as did ditching and dredging which widened waterway crossings while deepening their courses. As a consequence, old bridges needed to be moved upstream or to have their length extended, and a number of new ones had to be built. The CR#700N crossing of the Beaver Lake Ditch just west of Conrad had been spanned for some time, probably with a metal structure, before the township highway improvement plan got launched. In early 1915, the county commissioners ordered J. Ross Deardurff, the county surveyor and engineer, to prepare plans and specifications for a Conrad replacement bridge. Having approved Deardurff's proposals, including his estimate that the new structure would cost $5,800, the board sought bids by early May. At the letting, the board contracted with "the lowest and best bidders"--George A. Webber of Morocco at $3,400.00 for the concrete substructure and the Elkhart Bridge & Iron Company at $2,197.00 for the superstructure. Elkhart Bridge proposed an all-riveted 81-ft. 4-in. Warren deck-truss span in five 16-ft. panels and with a 16-ft roadway. The board named A. B. Jenkins as superintendent of construction. The new bridge, complete with a timber deck, was finished by the spring of 1916. The upper and lower chords run parallel to one another and maintain a truss depth of 10 ft. Almost all the members rely on angles and plates. A pair of angles (6"x6"Ls) riveted to each other--and reinforced in the most central panels with a cover plate--provide the inclined end-posts and top chord members. The lower chord members also consist of a pair of angles (6"x4"Ls) with a single plate added in the second and fourth panels, and a pair of plates added in the central panel. Angles dominate the webbing, too. Absent any verticals, the diagonals complete the triangular truss blocks. The pair of angles used for each diagonal member becomes lighter toward midspan (6"x4"Ls>3"x3"Ls). Both the top and bottom chords use angles for lateral bracing. Light angles provide sway framing between upper and lower panel points. Placed above and riveted through the top chord, I floor-beams extend 2 ft. beyond the trusses on each side. Six rows of 16-in. rolled I-beam stringers, beginning from concrete joist seats at the abutments and then bolted to the floor-beams' sides, carried the timber deck. Latticed guardrails originally demarked the roadway. This structure carried an established road over a significant ditch in Newton county. The road serviced the town of Conrad and its school and intersected with a major highway to Chicago. The ditch, in turn, was part of an extensive, belabored effort to remove the sloughs from several townships. The Beaver Lake Ditch had been spanned at this point for at least one generation of bridges. Indeed, the county moved "the old Conrad Bridge" to a new location when the new one was finished. An important local contractor built the very substantial concrete substructure and long retaining wall for this bridge. Elkhart Bridge designed and constructed more Warren deck structures than any other Indiana builder at the time. With a form not often used even then, the Conrad Bridge is one of very few extant examples of its kind in Indiana. It is the oldest of two that the prolific Elkhart firm planned and built. The design is simple and fabrication from angles particularly efficient. The trusses retain their original members, although the guardrails have been replaced. The Indiana Historical Society holds the firm's original drawings of the deck truss.
References Associated Engineering Consultants, Inc., Bridge Inventory & Inspection Report: Newton County (Nashville, 1973). Warren T. Hobson and Associates, Inc., Bridge Inspection Report: Newton County (Indianapolis, 1980). Elkhart Bridge & Iron Company, Drawings, D-230, Indiana Historical Society (Indianapolis). Engineering News-Record (20 May 1915) 78: 277. Newton County, "Commissioners Record," 14: 23-24, 168, 294, 353, 401, 465-464, 471-472, 478, 481, 483, 489, 495, 506, 514, 517-518. Newton County Enterprise (25 March 1915) p1,c5; (8 April 1915) p1,c6, p8c5.
Bridge Considered Historic By Survey: Yes
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