Roosevelt Lake Bridge, Gila County, Arizona

Although traffic congestion was important, the deciding factor for the new Roosevelt Lake Bridge was flood protection. Located about 305 m upstream of the dam, the new Roosevelt Lake Bridge is just below the confluence of the Salt River and Toronto Creek. The Arizona Department of Transportation based its selection of the best type of bridge for the crossing on economics. Because of the steep valley walls and the deep valley floor, underwater foundations were determined to be too costly. The two-lane bridge would have to span the lake with footings on each shore. Two engineering firms prepared complete construction plans of two alternatives: a steel box-rib-through-arch and a concrete stayed girder bridge. The box-rib-through-arch was selected for the steel alternative based on an in-depth study of three steel bridge types.