Bird's Eye View

by Tony Illia

A new glass pedestrian "Skywalk" that loops 3,800 ft. above the Colorado River will give visitors a new look at the Grand Canyon.

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The $8 million, cantilevered, U-shaped structure and accompanying visitor center are being built by the Hualapai Nation as part of the larger Grand Canyon West development in northwestern Arizona. The privately financed undertaking, estimated to cost more than $30 million, also includes a Western ranch and village on the rim of the canyon.

But it's the Skywalk that steals the show by giving visitors a floating sensation over the canyon floor.

"The whole idea is to make the Grand Canyon experience like nothing else in the world," said David Jin, a tribal business partner and creator of the Skywalk concept. "The Skywalk will have what I call a 720-degree view: 360 degrees around and 360 degrees up and down. And disabled people will be able go to the middle of the canyon."

The 65-ft.-wide pedestrian structure will extend 65 ft. from the canyon's edge.

The 10.2-ft.-wide, 2.2-in.-thick glass deck is supported by outer and inner steel-plate, welded-box beams that are 2 in. thick, 32 in. wide and 72 in. deep.

The beams are anchored to eight 32-in.-square steel columns tied to 2.5-in.-diameter, 46-ft.-long rebar embedded into solid limestone. Ninety-four pieces of rebar will be used in the foundation's four footings, which extend 46 ft. down into 16,000-psi rated rock.
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Designed by MRJ Architects of Las Vegas, the tempered, five-layer composite glass attaches to the beams using special swivel hardware that enables it to flex during harsh climate changes without cracking. A 5-ft. high, .82-in.-thick laminated glass wall railing will skirt the structure and give it a transparent appearance.

The structure is designed to withstand 100-per-sq.-ft. live loads as well as 100 mph winds from all directions - up, down and sideways. It uses three tuned-mass dampers located inside the box beams at the center of the radius to counteract vibration.

"The walkway can carry 164,500 lbs. of working load from center to center," said Bill Karren, a principal with Las Vegas-based Lochsa Engineering, LLC, the structural engineer. "Its ultimate load, however, is approximately 324,000 lbs., which is about one-third the weight of a Boeing 747."

APCO Construction Inc., the project's Las Vegas design-build contractor, is building the walkway alongside the cliff before sliding it into place. "The box beams will be cribbed above the columns then jacked and rolled into place," said Cliff Rogers, APCO's project manager. "We have a 700,000-lb. counterweight to secure it in place during the operation."

The Skywalk will have 85 lin. ft. of full-penetration welds securing it to the pile caps. That will result in a sturdy, rigid structure designed to withstand seismic forces.

A service trolley is being added under the crescent-shaped walk for cleaning and maintenance. The Skywalk extends over the canyon from a three-story, 25,000-sq.-ft. visitor center. The steel-framed structure will be clad with a combination of stone veneer, glass and EIFS. It will contain a museum, three restaurants and bars, a movie theater, VIP lounge, gift shop and meeting space.

The Skywalk, which began conceptual design in June 2004, is now scheduled to open by early 2007. APCO is self-forming the concrete work.

"Our Skywalk experience will be quiet and personal and compliment the canyon," said Sheri Yellowhawk, a tribal member and project spokesperson.

"The economic impact to the people of the Hualapai will be enormous."

Key Players

Owner: Hualapai Nation
General Contractor: APCO Construction
Architect:MRJ Architects
Structural Engineer: Lochsa Engineering
Steel: Century Steel/ Mark Steel
Glass: Accuracy Glass
Drilling:D.J. Scheffler
Crane/Rigging: Dielco Crane

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