In February 2003, the joint-venture team of R.E. Monks Construction Inc., Fountain Hills, Ariz., and Vastco Inc., Chino Valley, Ariz., landed the $21.4-million contract to build the 1.8-mile-long, four-lane Arizona approach. The difficult topography of tuff and basalt required 1.7- million cu yd of drill-and-blast excavation of the mountainside, performed by Western States Contracting Inc., Las Vegas. Material was crushed and reused as earthen embankment.

�The steep terrain was an initial challenge,� says R.E. Monks project engineer Pete Young. �As far as the overall scope, it�s a pretty simple project. At least there aren�t a lot of utilities in the way.� The team built a 16.7-ft-tall diamond interchange with1,300-ft-long ramps cutting into the mountainside, enabling two lanes of traffic to flow in each direction at Old Kingman Wash Road�the gateway to the Lake Mead National Recreation area.

The job includes a 902-ft-long bridge that crosses a 160-ft-deep ravine. Its six tapered piers support 77 prestressed, 128-ft-long concrete girders. �We had to come up with a complex scheme to place them in each instance,� Vastco project engineer Tim Kempkes says. �Due to wind and conditions, we would pick up some girders and change their location in mid-air in order to properly place them.�

Vastco used seven cranes to place the girders, from a 250-ton crawler crane with 200 ft of boom to a 22-ton hydraulic crane. The team finished the contract ahead of schedule in October 2004.

On the other side of the river, Edward Kraemer & Sons Inc., Plain, Wis., won a $30.1-million contract in August 2003 to build the 2.2-mile-long, four-lane Nevada approach. The job includes five new bridges and an interchange that provides access to an existing section of U.S. 93, which will become a Hoover Dam access road. One bridge, a 463-ft-long, three-span, steel-girder structure, crosses a 160-ft-deep ravine. A 300-ton crawler crane was positioned at the ravine bottom to help place the supporting piers, abutment caps and structural steel. Two hydraulic truck cranes at each span end placed the steel bridge decking.

KLB Construction Inc., the Lynn�wood, Wash.-based earthwork subcontractor, shaved 150 ft from one of the canyon walls to achieve the best angle for its construction. The project had 1.6-million cu yd of drill and blast excavation, with material screened and reused for 50,000 sq ft of 20-ft-tall mechanically stabilized earth retaining walls, says KLB project manager David Lingle.

�The Nevada side is significantly more challenging in terms of phasing and scheduling, with more logistical constraints and more volume in terms of material and structures,� says Zanetell. �But Kraemer was real strong in paying attention to those details.� Kraemer finished ahead of schedule in October 2005.

Construction of the main crossing across Black Canyon, �The Mike O�Callaghan-Pat Tillman Memorial Bridge� �named after former Nevada Gov. Mike O�Callaghan and professional football star Pat Tillman, killed as a soldier in Afghanistan�has not gone as smoothly as the approach work. When Congress failed to reauthorize the six-year Transportation Equity Act for the 21st Century (TEA-21) in 2003, construction was threatened even before the contract had been let. The completion date was pushed back a year, because the transportation bill contained the final $90-million piece of federal funding.

In June 2004, Arizona and Nevada each pledged $50 million in Grant Anticipation Revenue Vehicle, or GARVEE, bonds to keep construction moving. Transportation officials believe the project could become an example for other states that now face delayed reauthorization of the current federal highway bill. �Other states will take note of Arizona and Nevada using GARVEE bonds to keep the project going,� says Thomas Warne, a Salt Lake City-based transportation consultant and former director of the Utah Dept. of Transportation.

The cash infusion enabled FHWA to award the contract for the main crossing. Obayashi/PSM�s bid was 15.6% above the engineer�s estimate but $12.9 million below that of Peter Kiewit Sons� Inc., Omaha, and Flatiron Construction Corp., Longmont, Colo. Its proposed use of the cableway sparked industry interest. �Cableways aren�t a common thing to use in bridge construction,� says Khaled Mahmoud, chairman of the New York City-based Bridge Engineering Association.

But almost from the beginning, the team ran into problems. First, in early 2006, its local concrete supplier, Casino Ready Mix Inc., was found to be unlicensed, causing a 4-month delay. Then, in September 2006, 55-mile-per-hour winds caused the high lines to collapse.

Fortunately, work had stopped the day the system went down. The Nevada south tower failed, compromising adjoining tower support cables and causing them to fall in succession, like dominoes. The incident delayed construction for two years, pushing completion back to 2010. Obaysahi/PSM faces $8,000 a day in late fines after 1,271 working days, which could amount to millions in late penalties. FHWA is not ruling the incident a force majeure. The project was about 40% complete at the time.

The overall project should still finish within budget due to bids that came in 10% and 15% lower than expected, respectively, on the Nevada and Arizona approaches. Obayashi/PSM mobilized two interim cranes to continue work, while Cincinnati-based F&M Mafco Inc., with Canadian and Italian subcontractors, fabricated a replacement cableway system with �heavier components,� says Obayashi project sponsor Jim Stevens.

While the cableway system was being replaced, Obayashi/PSM mobilized a 330-ton crane on the Nevada side and a 135-ton crane on the Arizona side to build columns, pier caps, box girders, and arch segments. The new cableway system went into operation in January 2008. Replacement costs and accident details have not been disclosed because legal action is pending between American Bridge and Obayashi/PSM.

But the project�s troubles continued. On Nov. 24, 2008, ironworker Sherman Jones, 48, of Las Vegas, was killed while adjusting an alignment cable on the twin arches. Jones was untensioning a Nevada-side tower backstay using hydraulic pumps on the strand jack when the cable snapped. The U.S. Occupational Safety and Health Administration found Jones died from blunt-force trauma injuries and ruled the incident an accident. OSHA did not fine the contractor.

Officials hope the worst is over. Las Vegas Paving Corp. finished a $7-million contract for interim hot-mix asphalt surfacing in 2008. One last $8-million contract will soon go to bid for paving remaining roadway and tie-ins at U.S. 93, plus final signing and striping. The bridge now is scheduled to open in November 2010, coinciding with the 75th anniversary of the Hoover Dam.