Hoover Dam's Bridge Construction
The Las Vegas Sun reported on August 1, 2009, that the Colorado River Bridge Project was 85 percent completed. The bridge's twin support arches were near joining, 840 feet above the Colorado. The new bridge will bypass the Highway 93 crossing on top of Hoover Dam and divert traffic away from tourist attractions. The bypass will decrease travel time for interstate traffic and reduce the high rate of accidents in tourist bottlenecks at the dam.
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Dam
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The Hoover Dam hydroelectric project was built from 1931 to 1936, during the Great Depression, and spans the gorge of the Colorado River east of Las Vegas. Six Company, a consortium of six construction companies, was awarded the building contract for the massive dam, which it finished under budget and ahead of schedule. The approach to the roadway atop the dam is steep, and traffic winds over tedious switchbacks. By the 1960s, the roadway across the dam was outdated, and a bypass was proposed.
ISTEA
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The Intermodal Surface Transportation Efficiency Act of 1991 (ISTEA, or "ice tea") allocated $180 billion to maintain or build highways and bridges. In 1997, congressmen from Arizona and Nevada cited the "dangerously winding and steep approach roads" among reasons why the 1936 two-lane highway atop the bridge should be bypassed. At that time, 1,430 tons of hazardous materials crossed the narrow roadway daily, and 1,500 trucks and buses each day were compelled to cross the double-yellow traffic lines into the oncoming lane to traverse the switchbacks. During holidays, traffic was backed up as much as 8 miles.
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Site
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In 1997, Federal Highway Administration officials chose Sugarloaf Mountain, within sight of the dam, as the easiest accessible location for a four-lane approach to a new bridge. In year 2000, the environmental impact statement was still pending. Interstate trucking interests lobbied to keep the shortest route plan, arguing that if a longer route were built, truckers would use the dam road to save on fuel. After September 11, 2001, national security concerns expedited the project.
Construction Begins
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By January 2002, engineering work had started on site. Crux Subsurface bored 200-foot deep foundation holes into the canyon wall. Geologists from AMEC, Inc. of Phoenix tested the site to identify fractures that could endanger bridge supports. In February 2003, R.E. Monks Construction and Vastco Inc. of Fountain Hills, Arizona, were awarded a contract for work to include a 900-foot bridge, 1.8 miles of four-lane highway and concrete median, a traffic interchange at the bypass intersection, wildlife crossings, drainage and staining rock cuts to match the canyon walls.
Completion
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In August 2009, completion was expected by the end of the year. Concrete arches poured in place inside confined forms lacked only 6 feet to join the two sides of Black Canyon. Once joined, supporting towers and cables would be removed and work would begin on the columns to support the roadway above the arches. Two miles of approach roadway in Arizona cost $21.5 million, and the Nevada approach was $30 million. The total expense for the project was $240 million.
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