J. Polk Currin Swinging Bridge
Cottage Grove, Ore.
Award of Merit
Owner: City of Cottage Grove, Ore.
Lead Design Firm/Structural Engineer: Ausland Group
General Contractor: Hamilton Construction Inc.
Subcontractors: Mohawk Metal; SPS Inc.; Friends of Cottage Grove Swinging Bridge
The four-month effort to replace the 1920s-era landmark swinging bridge required some innovative construction approaches because the constrained, environmentally sensitive site did not lend itself to conventional ground-based construction techniques or equipment. Instead, the contractor took to the air, with an overhead cable trolley system to place materials along the new bridge structure. This technique saved construction time, eliminated the need to clear trees and relocate power lines and avoided disturbances to the vegetation along the riverbank.
To retain the visual features of the original structure, the new suspension bridge is crafted with weathering steel columns that have formed a patina matching the original coloring of the wooden timbers. The 1.25-in.-thick, high-strength steel bridge strand cables are only slightly thicker than the originals yet provide three times the support strength. Reusing the original concrete piers and angle-iron floor beams helped to reduce construction costs, while the marine-quality, pultruded fiberglass decking on the new bridge will last longer and require less maintenance than wooden planks.