Sources: Federal Highway Administration; CP staff; (March 2010 photo: FHWA)
By Don Marsh
Bridging America is the theme of an October 16 pedestrian event at the centerpiece of the U.S. 93 Hoover Dam Bypass: the Colorado River Bridge, whose 1,900-ft. roadway soars 900 ft. above the Black Canyon and bears on prolific twin concrete arches. The structure consists of segmental cast-in-place and precast concrete arch members, spandrel columns and piers, tub steel girders and stay-in-place metal forms for concrete deck. The arch span is 1,060 ft. and hovers about 1,500 ft. south of Hoover Dam, which has long carried U.S. 93 traffic as part of a treacherous Arizona-Nevada passage known for switchbacks, hairpin turns and high accident rates.
The $114 million bridge was built by a joint venture of Obayashi Corporation and PSM Construction USA, which served the job from an Arizona precast fabrication and steel girder staging yard. With four lanes plus pedestrian walkway, the structure is part of an overall $240 million project, spanning nearly 10 years and including two- and three-mile Arizona and Nevada approaches, respectively. U.S. 93 is considered a NAFTA route key to trade with Canada and Mexico, as well as a corridor vital to Arizona, Nevada and Utah. Freight carriers have endured rerouting since September 2001 over security concerns surrounding Hoover Dam.
The Bridging America walk leads into a scheduled November bypass opening. Participants will trek what Congress has designated the Mike O'Callaghan-Pat Tillman Memorial Bridge, honoring the former Nevada governor and Arizona State University/Arizona Cardinals football standout-turned-Army elite, fallen in 2004 from friendly fire while deployed in Afghanistan. The bypass opening is on the heels of the 75th anniversary of President Franklin Roosevelt's Hoover Dam dedication (September 30, 1935).