A Cliff-Hanger

by Graham Murdoch An artist's rendering of the Skywalk, perched 3,800 feet above the Colorado River. Graham Murdoch

step out onto the new Skywalk, and only a few sheets of glass will stand between you and a 15-second free-fall to the bottom of the Grand Canyon. Set to open late this year, this horseshoe-shaped footbridge (commissioned by the Hualapai Indian tribe, which owns the land) will jut 65 feet from the cliff edge and suspend 3,800 feet above the canyon floor, a height more than twice that of the world´s tallest skyscraper.

If you´re a bridge, the Grand Canyon is probably the last place you´d want to be: 90mph vertical winds whip upward with tornado-like force, a condition endured by no other bridge in the world. To secure the Skywalk, Lochsa Engineering in Las Vegas has cantilevered it atop the cliff with 94 steel rods that bore 46 feet into the limestone rock. As a result, it can support 70 tons of weight, equivalent to roughly 700 hefty men, although the maximum occupancy is set at 120 people. Three oscillating dampers-steel plates, each 3,200 pounds-inside the hollow bridge beams act as shock absorbers, moving up and down to neutralize the vibrations from foot traffic and wind gusts. For further support, the walkway itself will be constructed of three-inch-thick, heat-strengthened glass and enclosed by five-foot-tall glass walls.

Too tame for you? Lochsa hints at future plans to ratchet up the thrill
factor by turning a maintenance car designed to run on a track along the bottom of the Skywalk into a trolley ride for visitors.