Sending Steel Down the River

Completed last October 1990, the Roosevelt Lake Bridge is now the longest two-lane, single span, steel-arch bridge in North America, spanning 1,080 ft. Also, the longest steel arch bridge in the Arizona, it sits upstream from the 80-year-old Roosevelt Dam, the largest masonry dam in the world. The need to raise the dam also meant raising the bridge. The sight of a floating crane, with a 320 ft long boom and a 40 ft long jib, hoisting steel arch bridge segments of up to 90 tons, grabs attention. It's especially dramatic in Arizona, where most bridges span dry rivers. Without the 300 ton barge-mounted ringer crane and several other barges that carried the steel-arch pieces downriver, construction of the Roosevelt Lake Bridge would have been difficult. At the bridge site, the lake is too deep to build temporary piers. Geologic mapping revealed a foundation stratum about 300 ft deep at the center of the bridge site.