Glade Creek Bridge

Completed in 1988 by American Bridge, the Glade Creek Bridge project consisted of the erection of a 1,904-foot, three-span continuous Pratt Truss bridge over a deep gorge, with simply supported plate girder approach spans at each end. The interior supports for the truss are two main piers of monumental proportion, with the taller pier rising 350 feet above its foundation on the west slope of the gorge. Each main pier shaft is shaped to meet the geometric requirements of the truss and maximize efficiency throughout its height, with curves on both transverse and longitudinal pier faces creating an hourglass shape when viewed from an oblique angle. The truss ends are supported by 20-foot tall steel rocker bents, with the superstructure extending to stub abutments via simply supported, multi-girder steel spans.

The entire bridge is founded on 3-foot diameter reinforced concrete caissons drilled into rock. The steel truss carries the floor system and consists of a center span of 784 feet and side spans of 560 feet. The truss provides a maximum depth of 110 feet at the main piers and 40 feet and 45 feet at the ends of the side spans and the center of the main span, respectively. The bridge was constructed using a 2,879-foot span cableway with backspans of 640 feet and 546 feet. The cableway towers were 270 feet high, allowing a vertical clearance of approximately 50 feet under a 50-ton load at the center span. The cableway was able to luff 37 feet left or right to accomplish steel erection across the roadway width.

The load cable consisted of 2” by 3” cables carrying a trolley, moved horizontally by a 1-1/8” (29mm) wire rope inhaul/outhaul line. The cableway was anchored using large concrete anchor tiebacks secured into the rock with 55-foot long rock anchors. The project’s design engineer was URS.