2nd and Goal

Cardinals Stadium Nears End Zone

With more than two-thirds of its construction completed, the massive Cardinals Stadium continues its long run to an August 2006 touchdown, just in time for the 2006 football season. The 2007 Tostitos Fiesta Bowl and Super Bowl XLII in 2008 follow soon after.

The end zone is in sight for the Arizona Cardinals as construction on the new Cardinals Stadium in Glendale reaches its final months. The construction team has overcome many challenges during the project, including one of the largest roof-raisings in history.

advertisement

The $355 million project features many innovations for a sports complex. The design of the structure veers away from the generic, one-size-fits-all approach to stadium construction. It features a roll out playing field, a first for the Western Hemisphere and one of the first of its kind in the world. Most unique is the roof, with its two Brunel trusses spanning 700 feet atop four concrete super columns.

The stadium will seat 63,000 fans underneath two large retractable roof panels that will uncover the entire playing field, while a fabric 'halo' around the panels will provide shading. For special events, additional temporary seating will bring the total available seats to 72,900.

New York City-based Peter Eisenman Architects and HOK Sport of Kansas City, Mo. comprised the design team on the stadium. Eisenman, a world-renowned architect, was a unique choice for an American football stadium.

"Eisenman's design aesthetic is embedded in this building through and through," said Brent Leif, design development manager for Hunt Construction Group. "This is the best-designed stadium in the country right now. It pulls 'design' back into stadium construction. With this design team, you get

Eisenman's aesthetic and HOK's experience in stadium functionality, such as their skill with sight lines and amenities."

"One of the biggest plusses is that the Cardinals management has insisted and maintained its belief in wanting a world-class piece of architecture," said Peter Eisenman.

The design mimics the asymmetrical organic forms of desert life. Alternating sections of metal paneling and vertical glass slots echo the radiant form of a barrel cactus. At night, rays of light will pierce these slots extending the radiants outward in all directions from the stadium.

The ray pattern is layered throughout the entire design scheme, with the colors of the seating bowl coded to match the exterior's pattern. "This is not just a one-dimensional design," said Leif. "The ray pattern is three-dimensional. You'll get a new perspective from every vantage point - no two slots are the same."

The metal cladding, comprised of some 10,000 individual tongue-and-groove metal panels, hook onto the frame using adjustable clips to create the illusion of a rounded curve. The panels will reflect the predominant colors of the surrounding landscape and change its look as the sky changes.

Since the project's June 2003 groundbreaking, the retractable roof has been the center of attention. "The raising of the roof on schedule in February was the single most critical milestone we achieved," said Tab Baker, business manager for Hunt Construction Group. "Once the roof was successfully placed, it allowed subcontractors to begin working on the bowl area and the rest of the building, because the roof occupied the field while it was being assembled."

The roof can retract to provide an opening approximately 240-ft. wide by 360-ft. long over the playing field. Two massive trusses spanning 700 feet support the 5,500 tons of steel. Each truss, known as a Brunel truss, is 87-ft. tall and resembles an airplane wing. However, these 'wings' hold up the equivalent weight of 14 Boeing 747's and are three times as long.

Schuff Steel fabricated and erected the massive amounts of steel. "One of the most interesting features of this project is the erection," said Ed Carroll, a Schuff Steel senior project manager. "We will be putting lifting towers on the super-columns and lifting the trusses with cables to the bearing points."

The four super columns were specifically engineered to support both the roof and the lifting procedure. Each were formed using 1,050-cu.-yds. of 7,000 psi concrete.

"Each super column has a long vertical notch built in for the cables running down from the jacking frames," said Baker. The jacks attach to pick points in the trusses corners using 432 strand cables. Mammoet, a Dutch firm specializing in challenging lifts, handled the slow and careful hoisting of the trusses to a height of 171 feet.

"Once the roof reached that height, a 6-ft. wide by 17.5-ft. long by 5-ft. deep girder, called a transfer girder, was swung into place in a horizontal notch at the 156-ft. level in each of the four super columns," said Baker. "Then the roof was lowered back down to its final location, attached atop the transfer girders."

Incredibly, the entire procedure was completed over four days, with nearly constant rain the entire time. Nearly a million gallons of rainwater was pumped out during the lift.

Once the lift was complete, contractors began stretching a translucent fabric, known as Birdair, across the retractable panels and around the circumference, creating the asymmetrical halo, allowing light to pass through with a soft glow.

With the roof out of the way, workers could start on another innovative feature of the stadium, the roll-out, natural grass playing field.

"The field is built on a steel frame with 2" of metal decking and 2" of concrete on top," said Leif. "On top of the concrete is a waterproof liner, with a drainage mat and geo-textile fabric underneath the dirt and grass. Drainage is aided by a 2% pitch, crowned in the center so water runs east and west."

This 234-ft. by 404-ft. tray will ride to and from the stadium bowl on 13 rails, similar to railroad tracks, which run 1,100 ft. Each rail sits on its own concrete footer, with a high-strength concrete mix poured on either side of the rail to hold the lateral load. The wheels are essentially 'dumb', riding on top of the rails with only the center rail having any kind of guidance system to keep it on track.

"The two outer rails have the drive wheelbox system, which are powered by 76 one-horsepower motors," said Baker. "They are just enough power to overcome the static load of the tray's weight." The 12 million-pound tray takes about an hour to travel the 695-ft. distance from the stadium bowl to a below-grade flat recess outside of the stadium which houses the field tray when not in use.

When the field is moved out, a utility grid embedded in the 152,000-sq.-ft. stadium floor becomes accessible in order to host a variety of events such as trade shows, conventions and concerts. The grass can grow outside in the sun while inside all manner of events can take place without trampling the green.

As construction nears its summer 2006 completion date, the finishing touches are being applied throughout. At its peak, there were over 600 workers active on the 1.7 million-sq.-ft. project.

Fast Facts

Key Players

Click here for next Sports Construction Feature Story