Intense heat and high winds presented challenges for construction crews and materials.
the sharp turns, narrow roadways, inadequate shoulders, poor sight distance and low travel speeds that increased congestion and posed safety problems.
Since U.S. 93 is a high-priority trade route under the North American Free Trade Agreement and a major commercial route between Nevada and Arizona, the bypass will remove a major bottleneck to interstate and international commerce. “One of the huge drivers of the project was the historic and cultural context of the area,” said Dave Zanetell, Hoover Dam bypass project manager for the Federal Highway Administration Central Federal Lands Division (CFLD). “That had to be meshed with the physical environment and safety goals.”
A tough environment
With steep, rocky terrain and a desert environment, workers faced extraordinary physical and environmental challenges throughout construction.
Suspended 900 feet above the Colorado River, the bypass bridge is a true challenge. Workers contend with intense heat and dangerously high winds, since much of the construction relies on a high-wire pulley system, including a cable 1,300 feet above the river.
A California joint venture between Obayashi Corp. and PSM Construction USA Inc. is building the bridge, which is scheduled to open in late 2010.
Mitigating environmental issues
Contractors managed these issues while dealing with other environmental challenges, such as dust mitigation. During construction of the Arizona approach that leads U.S. 93 to the bridge, the Vastco/R.E. Monks Construction joint venture used a floating barge in Lake Mead to mitigate dust. The contractor implemented a pipe system, with a main line running through the lake and lateral lines coming off the main. “We were able to set up what was
Bridging history and the environment
Fitting the bypass in with the Hoover Dam’s status as a National Historic Landmark has been a key aspect of the project. It will enhance the experience for visitors by making the dam easier to tour and safeguarding the waters of Lake Mead and the Colorado River from hazardous spills or explosions. The finished bypass bridge will include a walkway and parking area for visitors to get out of their vehicles and view the dam.
basically a massive irrigation and sprinkler system to keep the dust down,” Beek said. The water system also helped with the construction by providing the water necessary for compaction and creating a more tightly contained, efficient jobsite. Crews had to be cognizant of desert tortoises, bighorn sheep and native plants. Workers received extensive environmental training and worked with the CFLD to manage these issues. Native plants were salvaged, placed in nurseries and replanted when construction was finished, Van Beek said.
Managing multiple stakeholders
The CFLD is part of the Federal Highway Administration that is managing the Hoover Dam project. The division is responsible for the design and construction of roads in the nation’s protected public lands. The CFLD had to coordinate with the Bureau of Reclamation, National Park Service, Hoover Dam and the Arizona and Nevada Departments of Transportation to address environmental, construction and safety challenges. “We came together as a multi-
agency, multi-stakeholder coalition to develop solutions that considered what were often competing interests,” Zanetell said. g&c
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