How to build a good halfpipe
ASPEN, Colo. (AP) — When properly prepared, a halfpipe is as much a snowboarder's canvas as the work of art itself — a 600-foot-long sculpture of smooth, icy symmetry designed to bring out each daredevil's talent and courage.
And when that halfpipe isn't made well, you end up with the sort of trouble we witnessed four years ago at the Sochi Olympics, where no snowboarder or freeskier seemed safe, and hardly any of the best riders got the chance to exhibit their best stuff.
Take American Arielle Gold. She was the defending world champion and a medal contender. But on her last practice run, her board wedged ever so slightly into a small bump toward the bottom of a mushy, misshapen Olympic halfpipe, and she went tumbling . She separated her shoulder and was out for the contest.
"That pipe was pretty bad," said Gold, who will be back at the Olympics this year on what she hopes is a better halfpipe in Pyeongchang. "Part of it, though, was I could've done more in terms of preparation, made more out of the practices we had. When we finally got to contest day, I hadn't really done much yet. It's kind of my fault, too. It's a learning experience."
Danny Davis called the Sochi halfpipe "garbage." Torah Bright, the 2010 gold medalist, said it was "brutal, and all you can kind of do is laugh." And though Shaun White wouldn't blame this, clearly the inferior pipe did not help him on the way to his fourth-place performance.
"We've all seen what winning the Olympics did for his career," said Chris Gunnarson, the president of Snow Park Tech (SPT), who spends his life making halfpipes, including those at Winter X Games, Dew Tour and the Burton U.S. Open. "It's a bummer when athletes don't have the opportunity to shine on the world's biggest stage."
Gunnarson has never reached a deal to build an Olympic halfpipe, in part because he's never come to an agreement with the IOC to provide the resources he feels are necessary to do it the right way.
He gave The Associated Press a rundown on the basics of how a pipe is constructed, and what makes the difference between a halfpipe the riders will love and one they'll fear:
As much as the actual shaping of the pipe, Gunnarson insists the quality of the snow — virtually all of which is manmade — will set the tone for how good the halfpipe will be. He equates making the snow to baking a cake. "You create a mixing bowl full of snow, and you have to make sure all the batter is really, really consistent. No lumps, dry spots, heavy wet spots," Gunnarson said. Architects will use between 13 million and 15 million gallons of water to produce between 400,000 and 600,000 cubic feet of snow (That's assuming there's an earthen halfpipe-shaped substructure to build upon, as is the case at most venues). Once the wall of the 22-foot-high halfpipe is built, it's pretty much set and there's no way to make big changes. The consistency of the snow is crucial because, Gunnarson says, unlike a slopestyle course or regular downhill run, "you can never go back up and add snow once it's up on a vertical surface."
Once the snow is made, workers start layering it in to build the decks — the flat top outside the pipe where often you'll see cameramen and fans standing. They constantly measure the height from the floor to the edge of the deck. The deck needs to be 22 feet high from the bottom of the halfpipe, and keeping exact measurements is crucial because the pipe is built at a steady 18 degree pitch from top to bottom. They work the snow down the pipe using winchcats — snowcats with large steel cables attached to help move big amounts of snow on steep angles — to layer the deck.
Measuring the Wall
After the decks are made, workers lay out a rope line from the top to the bottom of the run to determine where the lip (top) of the halfpipe and the top edge of the transitions (where it starts angling off into the bottom) are going to meet. Then, they take a chainsaw and follow that rope line down and make a 2 to 3 foot cut into the wall. They fill in the crevasse they've made with snow, then start filling in the halfpipe with snow. This is where the halfpipe cutter comes in. It's a huge tractor with blades and augers and blowers attached to elliptically shaped arms that help the builders push snow around and give the halfpipe its shape.
Once the walls are built, it's a matter of dishing out the bottom of the halfpipe to make it as smooth and seamless as possible as it flows into the transitions. If there are any imperfections, this is the time to fix them. Gunnarson compares it to doing a patch on drywall at home. "You do it by hand, patch it in and it freezes and bonds itself," Gunnarson said. In the end, they'll know whether they've built a quality pipe via the feedback from the riders — and the show those riders put on.
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