Constructing a Landmark

Jan 7th, 2011 | By | Category: 2010 Fall/Winter, Feature Stories

In five seasons as a middle linebacker for the Colorado School of Mines football team, Dave Zanetell learned a lot about teamwork. That education turned out to be every bit as useful as his Mines engineering degree—maybe even more so—when it came to building the Hoover Dam Bypass Bridge.

Officially opened in October, it’s the longest concrete-arch bridge in North America. The towering 300-foot precast/post-tensioned concrete columns supporting the roadway at either side of the arch are the tallest in the world, it’s the second-tallest bridge in North America and it’s one of the most technically challenging bridges ever constructed.

The director of engineering for the Central Federal Lands Highway Division (a unit of the Federal Highway Administration that encompasses all but five states west of the Mississippi), Zanetell personally led the Bypass Bridge project management team since his appointment in 2001.

Zanetell had no shortage of talented people and firms to pick from—the opportunity to build an iconic and technically challenging structure in the shadow of one of history’s greatest engineering achievements doesn’t come along very often. “It was one of the biggest jobs you can imagine; one that had the world’s attention. The best people in every discipline wanted to be involved, and given the job we had before us, it was a good thing,” he says. But, he adds, great people come with strong opinions.

Zanetell had to knit two state governments, four federal agencies, five general contractors, and dozens of consultants into an effective unit. It might easily have devolved into a chaotic tangle of turf wars, conflicting agendas, and clashing egos, but pulling from his old football playbook, Zanetell united these disparate players into a formidable team. “It took work to mold all of that talent into a cohesive group with a singular vision,” says Zanetell, who celebrated the completion of the $240-million span, on budget, this fall after almost six years of construction.

Strung nearly 1,000 feet above the Colorado River, the 1,900- foot arch-bridge solves problems that stymied engineers for more than three decades. Some of these were difficulties intrinsic to the physical site—high winds, challenging terrain, steep walls, and the canyon’s sheer depth and breadth—and some concerned the aesthetics.

A steel-truss arch would have been the most straightforward solution, but for the structure to blend with the Hoover Dam, the new bridge would also have to be concrete, and it was agreed that a sweeping arch would best complement the signature concave form of Hoover Dam.

While none of the engineers questioned whether a concrete-arch bridge would perform well once constructed, they all recognized that it made a difficult job much harder. Concrete is heavier than steel, and its structural integrity can be compromised if allowed to set up too fast—a big concern in the hot, dry conditions of the Southwest.

For these reasons, several previous plans to build a concrete bridge next to the dam had died during evaluation; as recently as the early nineties, a study declared a concrete bridge in this location to be marginally viable, at best.

“Almost every one of my trusted mentors and advisors told me not to take this job,” Zanetell laughs. “They said the engineering problems couldn’t be solved, the funds would never come, the agencies would never work together, the project would stall out and it would ruin my career. I saw it the opposite way—great things aren’t supposed to come easy.”

His friend and former football coach Marv Kay ’63 isn’t surprised to hear this from the former linebacker. “Dave was always at his best when the odds were in question,” says Kay, who recently attended the bridge opening as a personal guest of Zanetell’s. “The success he had was due to a great deal of effort and plain old hard work.”

Craig Schurig ’87 who played alongside Zanetell for Mines from 1982 until 1986 echoes Kay’s remarks. “Dave was an outstanding leader,” Schurig says. “Sometimes we were on the wrong side of the score, but Dave always played like we were about to win and demanded that everyone else do the same. He’s a winner, and he motivates those who work with him to be winners,” adds Shurig, who is now head football coach at Washburn University in Topeka, Kansas.

After receiving the assignment in 2001, his first act was to reorganize the team of primary stakeholders: the Federal Highway Administration; the U.S. Bureau of Reclamation, which operates Hoover Dam; the National Park Service, which administers the recreational lands directly behind the dam as well as Lake Mead; the Western Area Power Administration; and the transportation departments of the two states that the new bridge would connect—Nevada and Arizona.

“One of the first things we did when we brought the multiagency team together was to draw up a game plan that defined roles and responsibilities. That was not easy work. We were dealing with the most senior leaders of those organizations, and everybody wasn’t necessarily in the role they wanted to play,” says Zanetell.

“But it was the role and leadership structure the project needed. We got everybody’s signature on an operating agreement. Everybody bought in. And that was the beginning of creating a team with a unified vision.”

It also established the principle of team accountability. “If there’s one thing I learned playing football, it is accountability. You have to be accountable to your teammates and your assignment— every player, every position. A coach’s decisions may often be based on the input of others, but it is not subject to debate,” says Zanetell. “There comes a point when the team has to believe the coach will make the right call.”

After seeing posturing and bias pull too many projects off course, Zanetell attributes the successful management of the Bypass Bridge project to this centralized approach.

“It was amazing to see how this brought forth the best in people,” he says. “When we brought new contractors and staff on board, we didn’t just hand them the ball. We brought them into our team.”

The results speak for themselves. Since assembling pre-fabricated sections wasn’t feasible due to their weight, the entire arch was cast in place, one 25-foot section at a time. With each section formed using concrete pumped from the canyon rim, the ribs of the arch grew closer—also heavier. Until the 530-foot ribs came together, they had to be supported by elaborate arrays of steel cables strung from temporary towers constructed on either side of the canyon. “We effectively built a temporary cable-stay bridge to support the ribs during construction,” explains Zanetell.

Given the extreme temperatures experienced at the site, thermal control of the concrete curing process sometimes required elaborate measures, including cooling materials before mixing, pouring at night and, during the hottest months, even using liquid nitrogen to cool the mixed concrete before it was placed.

In August 2009, the last sections of the arch were poured, and alignment was found to be only three-eighths of an inch off center— well within the one-inch tolerance. For centuries, the completion of an arch bridge—marked by placement of the final keystones or, in the case of modern concrete bridges, a closure pour—has been a time for celebration. In the case of the Bypass Bridge, the closure-pour put the most critical and dangerous phase of the project behind them, and it was celebrated by just about everyone involved in its construction—but not Zanetell.

“I dearly wanted to be there,” he admits, “but it was a time for the crews to celebrate. For the management team, we had a year of difficult and dangerous work left. I had to make it clear to everyone that we couldn’t afford to lose focus.” David Goodyear, the design engineer for the project, who according to Zanetell is one of the world’s best long-span engineers, remarked that it was the most intensely managed project he could recall.

Now that the Bypass Bridge is open, it offers visitors a more spectacular view of Hoover Dam than ever before—so long as they take the time to walk out on the bridge. For safety reasons, the view is blocked for those driving over the bridge. And for visitors wanting to retrace the old path of Route 19, one-way traffic across the top of the dam is still permitted from the Nevada side.

As any football player can tell you, winning and losing can be contagious. Zanetell, whose 2007 promotion expanded his responsibilities to encompass administration of approximately 50 projects annually across 14 western states, hopes his team’s work on the Bypass Bridge can serve as a national model.

“The professionals who have worked on this job have been amazing in their commitment to it and their embrace of a team concept. That’s a hard thing to do, and it’s really special when you find a group of people who come together to make it happen. In civil engineering, Hoover Dam is your gold standard. But the leaders who were responsible for building it didn’t quit on that success. They built on that confidence and energy to put up Shasta Dam and other major structures. They used that momentum for the benefit of our country and our industry,” says Zanetell.

“That’s my goal—to take this success and create a sense of confidence and a sense of will so that there can be support for even greater endeavors.”

—Larry Borowsky

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One Comment to “Constructing a Landmark”

  1. John Kyffin '73 says:

    Thank you for the very informative and enjoyable article about the construction of the Hoover Dam Bypass Bridge. Mr. Zanetell and his team have provided a practical and aesthetically pleasing solution to a problem others avoided. All of the participants, the crews, the contractors, the suppliers, the designers, and the managers share the accomplishment.

    It is appropriate for Colorado School of Mines to claim some reflected admiration. Large, visible projects like this bridge can be pointed to with pride by the school and held up as an example of the best Mines can offer.

    As I look at the photos provided with the article, I see another useful and visible project completed by Mines graduates. On the Nevada side of the canyon, what looks like a big concrete silo is the surface structure of the visitor’s elevator shaft constructed by Frontier-Kemper Constructors. Frontier Constructors (which merged with Kemper construction to form FKCI) was founded by Mines graduates Dan McFadden ’63 and Dyke Howell ’63. Mines graduate Denis McInerny was also part of FKCI. Coach Marv Kay also worked for Frontier Constructors on at least two projects that I recall. There is another FKCI project hidden in this picture: the company refurbished the overflow spillways on both sides of the dam.

    I point these projects out because there are many important infrastructure projects involving Mines graduates that are not highly visible. These include highway tunnels, subways, water tunnels, storm water storage tunnels and many mining related facilities. Mining seems to be in low regard at Mines these days. Perhaps you could address that by highlighting some of these less visible projects.

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