Old IN-37 Bridge

Information and Findings From DHPA Historic Bridge Survey

Statement of Significance

One of the state's longer structures of its kind to survive, the heavy-duty and unadorned spans are of standard design. The whole retains its integrity.

Architectural Description

Concrete abutments, wingwalls, and piers support the three-span Warren pony truss. The riveted structure extends 232' in seven panels for each span. The western trusses are offset about one panel to the south. The all-interior verticals are manufactured from pairs of angles riveted together with stay plates and reinforced with external sway bracing. The diagonals, growing increasingly lighter toward midspan, are made of a pair of angles (doubled in the outer panel) also riveted together with stay plates. The I floor beams are riveted to gussets and the verticals above the lower chord and carry the concrete deck with its 20' roadway.

Other Information

The Vincennes Bridge Company of Vincennes, Indiana, bid $27,558.47 to build this three-span skewed structure (30deg.L) on concrete abutments and piers in July 1925. The bid came in about seven thousand below the state engineers' estimate, although in the end Vincennes was paid two thousand dollars over its bid. The bridge was complete by July 1926. The ISHC relied on an early standard plan for 77-ft., riveted, half-hip, Warren pony-truss spans with 20-ft. roadways. The 8-ft. 9-in. deep trusses carry seven 11-ft. wide panels. The external sway braces share battens with the all-interior verticals--each of two pairs of angles (3.5"x2.5"Ls) riveted together. The diagonals are heavier towards the ends (4Ls@3.5x3) than toward midspan (2Ls@3.5"x2.5"), each member riveted together with battens. The upper and lower chord members, on the other hand, become increasingly heavier toward midspan. For the top, a pair of 10-in. channels grow from 15.3 lbs to 20 lbs. For the bottom, a single pair of angles (6"x3.5"Ls) serve in the outer panel; thereafter the pairs are doubled. The ISHC specified fairly heavy I-floor-beams (24"@79.9#). These were riveted to the verticals above the lower chord and to their sides were attached seven rows of rolled 10-in. Is (@25.4#) as stringers, together carrying the concrete deck. Angles supply the lower sway bracing. Post and channel guardrails line the trusses.

This is probably the oldest extant state-design Warren pony-truss structures. It is multi-span, skewed, and retains its original members. A notable Indiana bridge builder fabricated and erected the trusses along with the substructure.

Bridge Considered Historic By Survey: Yes