For safe deceleration, you can only decelerate at a constant rate of about 3 Gs before things automatically become dangerous for the average person. They’d be moving at about 120-150 mph. Let’s say 135 mph, or 200 feet per second. Decelerating at 3 Gs, they’d need a half pipe with a smooth curve about 7 seconds, or 840 feet per quarter circle (half-halfpipe).

Now this is where I’m not sure, are half pipes smooth half circles? If they are, then you’d want a half pipe with a radius of like 535 feet. If not, then I’m stumped. Any skaters with input?