http://www.post-gazette.com/pg/06271/725831-100.stm
The Superpipe, shaped like the letter U, will be 450 feet long and 56 feet wide. The 18-foot-high walls will enable skiers and snowboarders to drop in from either side and gain enough momentum to jump above the lip of the wall on the other side. They can land there or do a 180-degree turn in mid-air and return to the other side.