The Hoover Dam Bypass’ goal is better and more safely serve the public and the operations of Hoover Dam in an environmentally responsible manner.

Few structures today share Hoover Dam’s reputation as one of the most impressive and complex engineering and architectural achievements in the world. So when the Central Federal Lands Division of the Federal Highway Administration (FHWA) started planning an alternate route around Hoover Dam, the agency knew it had to be a structure that would complement and live up to the dam’s history and reputation. “We are building a facility in the shadow of what is one of the greatest engineering feats in the country, and that’s quite a reminder of the standards that we need to uphold,” says Dave Zanetell, FHA project manager. “We are working in a place that has achieved greatness and it is our job to live up to that standard.”

The goal: design and construct a bypass that will better and more safely serve the public, surrounding economies and the operations of the Hoover Dam in an environmentally responsible manner.

The best route to meet this goal has come in the form of a $234 million project to build 3.5 miles of four-lane highway and a 1,960-foot-long, 88-foot-wide arched bridge over the Colorado River. The bridge is being constructed under a joint venture between Obayashi USA of San Francisco and PSM Construction USA Inc. of Brisbane, Calif., which won the contract in 2004.

Plagued by Success
The need for the project is driven by the heavy volume of commercial and tourist traffic on U.S. Route 93, the two-lane highway across the dam. An estimated 17,000 vehicles and trucks cross it every day.  

“I think the root purpose and need for the project is an overwhelming need for the job to address congestion,” Zanetell says. “The accident rate is three times that of U.S. 93 on either end of the bypass. You have 6 million pedestrians interfacing with a major U.S. highway.”

Aside from serving tourists eager to get a glimpse of the dam and the vast canyon below it, Route 93 is the main link between Arizona, Nevada and Utah for commercial truckers. The highway is on the North American Free Trade Agreement’s main connector route between Mexico and Canada and is also considered a high-priority corridor by the National Highway System because it links Las Vegas and Phoenix. Aside from traffic congestion, the existing route is a narrow and curvy one, winding its way through the canyon and making the trip potentially dangerous.

The overall design and construction of the project is overseen by a project management team led by FHWA and includings stakeholders the Arizona and Nevada departments of transportation, the U.S. Bureau of Reclamation, the National Parks Service and the Western Area Power Administration. The bypass is funded by federal, Arizona and Nevada state money.

“It has truly been a collaborative effort and it’s frankly an honor and it’s humbling for us to get the opportunity to lead a job of this importance,” Zanetell asserts. “We have seen all of the stakeholders participate actively and help shape the outcome of the project for the core. It’s been about how we take our visions and our approach and leverage that into hands of the design and construction industries, and work with them to deliver our vision.”

Because each entity in the joint venture has significant experience in heavy highway and civil construction, the partnership was a win-win for Obayashi, PSM and the project management team, says Jim Stevens, project sponsor with Obayashi-PSM.

“First and foremost in terms of the big picture, the project that we are embarking on is really one of the highest obligations of a contractor and engineer,” Zanetell says.

“As we moved forward in our design and delivery, we wanted to focus on a team that had the breadth of skills to deliver all aspects of the bypass. It’s more than building bridges. It’s having the skills and ability to mobilize and effectively engage those skills in alignment with our vision – that was probably the real priority at the time.”

Collaboration between the project team and industry leaders occurred in a non-traditional way, Zanetell says. Early engagement with the industry through outreach and gaining technical feedback was crucial in devising the best strategy for the project. Working with the industry rather than requiring that those involved take a specific approach was the key for the project. “We have a strong philosophy of cradle-to-grave management; we don’t hand the project off at certain phases,” he says.

“A job like this is truly what I would call integrated design/construction,” Zanetell explains. “Everything that the contractor does in the erection methodologies and the approach have the potential to impact the bridge, and therefore, it’s truly a job that you have to organize in teams so contractors and our engineering team work hand-in-hand.”

Delivering the Project
Prior to the construction of the bridge, two approaching highways were built leading up to the Colorado River in Arizona and Nevada. In October 2004, following two years of construction, a 1.8-mile approach from Route 93 to the Arizona side of the river was finished under a partnership between R.E. Monks Construction Inc. of Fountain Hills, Ariz., and Vastco Inc. of Chino Valley, Ariz. The 2.1-mile Nevada approach finished in October 2005 and was built by Edward Kraemer & Sons Inc., of Plain, Wis.

By January 2005, Obayashi and PSM had started construction on the composite steel and concrete deck arch bridge. This type of bridge was chosen for the project because of its relatively low cost, technical excellence, aesthetic appeal and fit with an accelerated schedule.

Working 890 feet above the Colorado River, the joint venture has used proprietary construction methods and technologies. To prepare the site, the two firms along with a team of subcontractors excavated roughly 40,000 cubic yards of rock at the abutments, approach piers and arch footings. The structure contains 10 pier footings and a total of 440 column segments.

To move materials and set precast column segments for the bridge required the crew to devise a system on-site before construction could begin. The joint venture used two tower cranes located on opposite sides of the canyon, connected via dual high lines.

With roughly 120 employees and as many as three subcontractors working on-site on a project of this magnitude, Deputy Project Manager Jeff St. John says coordination has been integral in moving forward. Meetings are held weekly with the joint venture team and between the project management team and governmental agencies.

Hitting a Road Block
On Sept. 15, 2006, the project hit a major snag when the two, 333-foot-tall highline cableway cranes used to transport materials collapsed in a windstorm. The event moved the project completion date from 2008 to 2010. At the time, the project was nearly 40 percent complete. Without the highline system, transporting materials to construct the columns and arch segments was impossible.

Despite the setback, the team procured two state-of-the-art temporary cranes to keep construction moving while the design, procurement and fabrication of a new highline system was underway. The team is using a Manitowac 2250 crane on the Nevada side of the canyon; it has a 330-ton capacity with a 320-foot boom. On the Arizona side, the team erected a S70 Derrick crane with a 135-ton capacity and 330-foot boom. Both cranes have made possible the continued construction of columns, box girders, pier caps and arch segments on the approach spans.

Once the new highline system is erected at the end of the year, work will resume on the remaining portions of the arches. According to St. John, the first segments of the arch are complete and were constructed by pouring concrete in sections. When complete, each arch will contain 53 concrete segments.

On-site material storage and fabrication has also been crucial to progress, says Fredrick Lazar, contract administration manager. A nearby precast yard and batch plant quickened column fabrication. Once the highline system is in place, he says, the project “is set to move expeditiously.”

“When the contractors’ delivery system failed, that was a setback for everybody, but since that time, the contractors have had an extremely productive year incorporating an alternative delivery system,” Zanetell explains. “We have made significant progress toward completion of the bridge utilizing an alternative system.”

Intense heat, high winds and 10-hour work days make the bypass project all the more intense. According to Lazar, worksite conditions “are pretty unique. There is a very rugged topography over the deep gorge with very deep and jagged sides.” To approach the piers, the crews have to climb up and work on the scaffolding – sometimes 300 feet high.

To mitigate risk, men are securely tied to safety cables via a full-body harness and lanyards before they access pier caps and other areas with fall hazards. The crew also beats the hot climate by starting a shift at 5 a.m. and ending before the hottest part of the day approaches. Work then resumes late afternoon and into the early morning hours.

Despite the complexity of the project, its management team and contractors are working closely to minimize schedule delays and position the joint venture to complete the project by the end of 2010. “I think everybody who has been involved in this job, no matter what their role, is going to feel an enormous sense of pride, achievement and accomplishment,” Zanetell says. “For the rest of our lives, we will be joined together by what we have collectively accomplished.”