Bridge No: 3340002300100

Asset ID: 810

County: McCormick

Bridge Name: Modoc Bridge

Facility Carried: SC 23

Feature Intersected: Stevens Creek

Year Built: 1937

Year Reconstructed:

Main Structure Type: Pony Truss

Design: Warren (riveted)

Main Material: Steel

Railing Type: Concrete Balustrades

Number of Main Spans: 1

Number of Approach Spans: 8

Approach Type: T Beam, reinforces concrete

Structure Length: 480 feet

Structure Width: 21.2 feet

Setting: The bridge carries a 2 lane road over a stream in a sparsely developed, forested setting.

The main span of the 9 span, 480'-long bridge is a 108'-long, Warren with polygonal chords and verticals pony truss span. The deck is 20' wide. The eight T beam approach spans are composed of three beams.They are finished with a handsome balustrade and are supported on well-detailed 2-column bents finished in the Neo-classical taste. The truss lines have traditional built up chords, but the web members (diagonals and verticals) are rolled section.A handsome loop-pattern iron railing is set inside the truss lines, and the span is finished with a concrete deck with integral curbs.The bridge appears to be complete.

The 1937 riveted Warren pony truss bridge built by the state highway department on a state highway stands as a complete example of the important standard design for both the main spans and the approaches.The use of rolled section for the web members (diagonal and verticals) represents a significant technological advance that started nationally in the late 1920s and came into widespread practice in the 1930s.Rolled section reduces the potential for moisture-related corrosion because there are no “joints” between steel shapes.The Warren with polygonal upper chords and verticals to brace the chords proved a particularly strong and economical design for the department, and it was used all across the state starting in the late 1920s. The superb detailing of the T beam approach spans reflects Capt. Barnwell’s commitment to bridge aesthetics that is a hallmark of the best pre-World War II bridges done by the department.The Modoc Bridge is historically and technologically significant of a once-common state highway department design, for its association with the development of the state highway system, and its high artistic merit under Criteria A and C. The bridge builder, Carolina Steel and Iron Company, was Greensboro based.