I'm reminded of this water slide at the Gold Coast's Wet and Wild - you end up going upside down - but in order to attain the velocity required to make the loop, you need to be dropped from a particular height, only some people don't make it - so they have a single access point into the tube where people who haven't made it, can get out, but I'm sure it wouldn't be a fun experience, so I opted for not going on that slide, even though my kids were pleading with me to do it. No thanks.
The hyperloop looks amazing, but my heart rate went up reading that document, and it wasn't out of excitement