"But here's the question--if you have these things in scenic parks, what happens when one person stops, and the person behind them keeps pedaling?"
Easy. run a parallel track and place optional track switchers every 30 feet or so.
this is an Awesome idea. I have visions of these being installed between the roofs of buildings, parking garages, shopping malls that way you don't have to ride the elevator all the way down to street level and then all the way back up.