Although I'm aware of the fact that brick direction would interfere, possibly a set of modded bricks that set direction, with a basic vehicle model that rides along them at a speed of which is controlled by events.
Sounds a tad complex, but it'd actually allow for basic rollercoaster rides, and basic train builds, to be developed.
And, yes, I am COMPLETELY aware of the fact that this has been suggested several times before. However, it seems that we have more things to help out with such addon. Ex: events.