Moosh, I built one of those out of Knex, actually! It even worked too, a chain took it all the way to the top of one tower, where it was dropped and then traveled up the next one. I built it out of the original Knex roller coaster, so I had to fashion a system to keep the car on the track. It worked quite well for an original design.
I'm sure I could find pics if anyone was interested...