The work requires a 900-ft-long precast concrete girder bridge, which crosses a 200-ft-deep ravine, plus a cast-in-place intersection bridge at the Hoover Dam Access and Kingman Wash roads. The two-year undertaking, slated to finish by October 2004, also includes 1.7-million cu yd worth of difficult excavation that must be drilled and blasted. The A+B contract has liquidateddamages of up to $10,000 a day, but also includes 5% bonuses for materials that exceed specifications.
"Essentially, it's a great way of ensuring that all parties deliver a quality project that will last over a long period of time," says Dave Zanetell, FHWA's project manager.
In October, the Western Power Administration awarded a $9.6-million utilityrelocation contract to Kansas City-based Par Electrical Contractors Inc. to move eight steel lattice transmission towers and accompanying 230-kV and 440-kV lines from the path of the bridge. The first phase will finish in June.
The project is expected to greatly relieve the congested two-lane U.S. 95 highway, identified as a NAFTA route, which currently runs over the crest of the dam. The 2,000-ft-long bypass bridge will be a single-arch, steel-and-concrete composite structure crossing the Colorado River 1,700-ft downstream from the dam. HDR Inc., Omaha, with Sverdrup Civil Inc., a unit of Pasadena-based Jacobs Engineering Group Inc., and T.Y. Lin International, San Francisco, are the project's engineering-design team (ENR 7/23/01 pg. 7)
Originally estimated at $198 million, FHWA adjusted its total costs to $234 million after the geotechnical survey, conducted by London-based AMEC PLC, found that Black Canyon's rigorous slopes would require pricey excavation. Contractors must create 90° and 73° sheer drops at theNevada and Arizona sides, respectively, to minimize the amount of excavation otherwise needed for more gradual transitions.Controlled explosives will be used to carve-out the canyon walls, which descend 850 ft to the Colorado River.
FHWA plans to advertise the second phase, the 2.5-mile, four-lane Nevada approach, in June followed by the bridge structure itself in October. The project is scheduled for completion in 2007.onstruction has recently begun on the first phase of the Federal Highway Administration's Hoover Dam bypass bridge . The joint-venture team of R.E. Monks Construction Co., Fountain Hills, Ariz., and Chino Valley, Ariz.-based Vastco Inc. landed the initial $21.5-million contract to build a 1.8-mile four-lane asphalt roadway from U.S. 93 to the Arizona side of the Colorado River.