The Hoover Dam bypass bridge, known officially as the Mike O'Callaghan-Pat Tillman Memorial Bridge, is being built about a half-mile downriver from the dam across Black Canyon. When completed, it will be 1,900 feet long with a 1,080-foot main span. The four-lane bridge (US93), 840 feet above the river, will be the first concrete-steel-composite arch bridge ever built in the U.S.
The bridge project was about halfway completed and well on its way toward its scheduled 2008 grand opening when, in the late afternoon of Friday Sept. 15, 2006, high winds snapped a 2,500-foot-long pulley-type "high-line crane" system that spanned Black Canyon and was used to transport heavy materials for the building of the bridge below. The snapped cable, in turn, toppled the two 300-foot-tall towers on both sides of the canyon that held up the cable. No one was injured in the mishap, though the mishap delayed the project by roughly two years.
The new high-line system was completed in January 2008. A couple of months later in March, the approach spans, consisting of seven concrete columns -- five on the Nevada side and two on the Arizona side -- were completed.
The fourth phase of the project, asphalt paving and guardrail installation on approximately 75% of the approach to the bridge itself, was completed in June.
Work now to be completed includes erecting two temporary towers at the ends of the approach span decks to anchor a new cable system needed to finish construction of the arch; the bridge-support arch is scheduled to be completed a year from now in September 2009. Once the arch is self-supporting, the cables and temporary towers will be removed; the bridge roadway will be built on top of the arch.
Finally, short sections between the approach and the bridge will be tied in, then signs, road striping, barriers, and pedestrian facilities will be completed.
The Mike O'Callaghan-Pat Tillman Memorial Bridge is now scheduled to be open to traffic sometime in the fourth quarter of 2010.
