...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 Lynnwood, 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...
