A Tokyo-based joint venture is the apparent low bidder for construction of the centerpiece of the Federal Highway Administration’s Hoover Dam Bridge project. Obayashi Corp. and P.S. Mitsubishi Construction Co. Ltd., beat three other teams with a $114-million low bid for the 1,905-ft-long single-arch bridge to be built 1,500 ft downstream from the dam.

Although 15.6% above engineer’s estimate, the A+B bid is still $12.9 million below the runner-up team of Peter Kiewit Sons' Inc., Omaha, and Flatiron Construction Corp., Longmont, Colo. "It’s an extremely volatile market in terms of steel and concrete," says F. Dave Zanetell, FHWA project manager. He anticipates a project award by month’s end.

The $21.4-million, 1.8-mile-long Arizona approach, being built by R.E. Monks Construction Inc., Fountain Hills, Ariz., with Chino Valley, Ariz.-based Vastco Inc., is scheduled to finish in November. Edward Kraemer & Sons Inc., Plain, Wisc., should wrap up the $30.1-million, 2.2-mile-long Nevada approach by Oct. 2005. Both bids came in at 10% to 15% below engineer’s estimate, creating a financial cushion for the $234-million bridge, Zanetell says.

Construction of the concrete-and-steel composite main span poses daunting challenges due to the canyon's sheer walls and a climate where temperatures routinely reach 120° F. Designed by an HDR Inc., Omaha-led team, the structure will rise 890 ft over the Colorado River and will be North America’s longest single concrete span.

FHWA has proposed two erection sequences: using dual towers with tiebacks to cast the span in place, or place precast bridge segments with cranes. The choice will be made after the contract is awarded.

Delayed reauthorization of the federal highway bill pushed project completion back a year to 2008 (ENR 7/12 p. 12). Arizona and Nevada have committed $50 million each in Grant Anticipation Revenue Vehicle bonds.