Against The Wind

The working environment at the Grand Canyon can be summed up in one word –harsh. There’s blistering heat in the summer and freezing nighttime temperatures in the winter. And…wind. Not just a breezy, little wind. Giant, raging gusts of it – 85+ mph. Now, try building a 65-foot glass and steel skywalk over the canyon in those blustery conditions.

“We wanted to find out what happens to wind at these speeds when it hits the side of a huge cliff,” says Contractor Cliff Rogers of APCO Construction. “We had wind measurements from airports in the vicinity, but not on the canyon edge.”

The skywalk construction team worked with RWDI Consultants from Guelph, Ontario, to determine how wind pressures would guide design and construction to avoid vibrations on the walkway. Rogers also performed an experiment himself, creating his own version of an anemometer – an instrument that measures and displays wind speed and other wind-related conditions – to gauge actual speeds.

“We constructed a vertical, metal tube and put an anemometer in it and hung it over` the side of the canyon,” Rogers said. “Using this, we deduced that when the wind came from the east and hit the sheerwall, it velocitized to a 13 percent increase over wind speed with an updraft, clocking in at 100 mph. So we designed things to accommodate this extreme factor.”

Contractors placed three tuned mass dampers specifically calibrated to meet the wind and weight requirements inside the walkway’s horseshoe frame to make it structurally sound by distributing the weight on the glass bridge. This keeps the walkway from “galloping” and vibrating underneath visitors’ feet during windy conditions.