Upgrading US-93 In Arizona

By Terry Ertter | September 28, 2010

What's the scariest highway you've ever driven? Ask one person in each of the 50 states, and you'll get at least 40 different answers. Ask 50 people in one state, and you could get the same answer over and over again.

It's no coincidence that a large portion of the roadbuilding articles in Rocky Mountain Construction deal with highways that rank near the top of the lists of most frightening in their states. States are putting their scarce dollars where the problems are. In this part of the country, most of the dangerous highways have two things in common:

  • They pass through rugged terrain that is a highway engineering nightmare. Steep grades, solid rock and crumbling hillsides mark the terrain. The mountains here are young and unforgiving to travelers.
  • Population trends have overloaded the highways far beyond anything they were originally built to handle. The roads are packed with impatient drivers willing to take crazy chances to get around the slowpokes in front of them.

Arizona drivers will recognize that this perfectly describes US-93 between Wickenburg and the highway's junction with I-40 east of Kingman. Most who have made the trek south on a Sunday afternoon have stories to tell. They've seen the endless lines of cars returning to the Phoenix area from Las Vegas, more than a few driven by angry, sleep-deprived gamblers whose weekends did not go as they had hoped. Drivers are passing on blind corners at high speeds and frantically forcing their way back into line to avoid collisions.

The highway, with its many long, straight stretches that suddenly transition into sharp winding turns, has a grim history. Removing the hazards on the 107-mile stretch of highway has long been a high priority for the Arizona Department of Transportation, but limited resources and the difficult terrain have made the work slow going.

One of the nastiest stretches is currently being widened and otherwise improved. The Arizona Department of Transportation calls it the Cottonwood Canyon to Bridle Creek Project. Regular drivers on US-93 know it as the 4.5-mile climb from the Santa Maria River to the Bagdad turnoff. When work began, the stretch had two lanes — and occasional short passing lanes — winding through tight corners on a steep grade through a rocky canyon.

The junction with the highway to Bagdad marks the northern end of the project. Bagdad is one of Arizona's large copper mining operations, and feeding the mine requires a constant stream of transport trucks. Many of the trucks are hauling massive machinery to and from the mine. Big trucks, steep grades, impatient drivers and two-lane highways are always a dangerous mix.

ADOT finalized design of the project in 2005 and released it for bids. Southwest Asphalt Paving earned the contract with a bid of $26 million and began work at the site in October 2005. Southwest Asphalt Paving, a business unit of Fisher Industries, is a relatively new player among the few companies competing for major highway jobs in Arizona. Sam Grasmick, general manager of Arizona operations, says the company has raised its profile rapidly in the two years since entering the construction side of the industry.

Tom Fisher started his company as a crushing operation when he moved to Tempe in 1997 from Dickinson, N.D., where his family has operated a crushing and highway construction company for years. In addition to the Arizona operation, Fisher has crushing operations nationwide and construction operations in Colorado, Nevada and New Mexico.

The 4.5 miles of the US-93 job present a number of challenges. Widening the entire stretch to two lanes in each direction requires more than a million yards of excavation, with extensive drilling and shooting of granite and calcified cobble in the narrow canyon. When completed near the end of 2007, the stretch will have two new bridges and four box culverts. Grasmick says he expects to have all four lanes open to traffic by May or June with detailing and finish work continuing to October or November.

Deciding how to construct the bridge foundations called for some innovative thinking. Bedrock was nearly a hundred feet down at the bridge sites, and there was a box culvert between the surface and the bedrock. Design plans called for excavation of the surface material to leave the creek flowing naturally at the bottom of the canyon. ADOT wanted the canyon walls exposed to emphasize the natural beauty of the setting, but removing the surface material early in the project was not practical.

The bridge subcontractor, Vastco of Prescott, Ariz., hired Becho Inc. to drill eight shafts (four for each bridge) through the surface material and into the bedrock. The Salt Lake City contractor had to drill each shaft to no more than an 84-inch diameter. Whenever a drill hit a boulder, Becho had to either drill through it or blast it.

A uniform 84-inch diameter was essential because the bridge caissons and columns were each poured from the top down monolithically, with the surrounding material serving as a mold. Later in the project, that surrounding material will be removed to expose the columns, the new creek bed and the canyon walls. Grasmick says he has not heard of this process being used on any other bridge construction project.

"Normally, we would excavate to the base of the caisson," says Grasmick. "We would build the caisson first, then attach a preformed column to it or pour the column on top of it."

Jodi Sorrell of ADOT notes that the project will complete widening and improvement work on the 40-mile stretch of US-93 from the Santa Maria River to Wikieup. Two other projects between Wikieup and the I-40 interchange have been accelerated by ADOT from fiscal 2009 to 2007. The McGarry's Wash Project near the interchange will add two lanes to a 2-mile stretch of highway. The other project will add two lanes to a 1-mile segment at Tompkins Canyon just north of Wikieup.

Two other sections will enter the design phase this year, with construction planned to begin in 2008. The Ranch Road Southbound Project is a 2-mile stretch about halfway between Wikieup and the interchange. Another 2-mile project is at Antelope Wash near I-40.

Of course, there's a lot more to US-93 than just the section between Wickenberg and I-40. The bridge bypassing Hoover Dam at the Colorado River will continue to be the crown jewel construction project in the Western U.S. for the next few years. US-93 between the bridge and Kingman will also get plenty of attention, due to developers planning to build more than 100,000 homes in five developments in the area.

Providing two lanes in each direction makes US-93 a much safer highway than it was in 2000 when Reader's Digest named it Arizona's most dangerous. That goal is finally in sight.