Track-based movement, ideas on implementation?

I have a few ideas I want to work on, some of which require track-based movement. A good example of this kind of movement would be a roller coaster (although I'm not building that myself).

I'm relatively new to LSL, but the language isn't an issue (I pick up new programming languages on a regular basis). It's more an understanding of how to make the scripts interact with the world, that is with physical (or non-phys) objects, sensors, communications, etc. I don't (yet) know the best ways of accomplishing everything in SL.

Any ideas? The thought of creating lots and lots of prims all sensoring or messaging or similar sounds like it might hurt sim performance..... Trying to do the necessary mathematics on prims like an long thin cylinder might also be painful and still requires some form of communication to move along the cylinder and jump to the next.

I thought being able to read/write a texture (per-pixel) in game would be great, but no such thing exists as far as I see.

Your thoughts...

Oh, and I know of course I could come up with mathematical models (perhaps parameterized in a note) to implement the movement, and probably rather cheaply, and then make the geometry to match.

But I'm hoping for something a little more dynamic than that, since changing the geometry around to match algorithms could get painful in itself.

Two examples of track-based movement are the tram Luna/the city and the ski lifts in the snow sims.

I believe both are implemented as vehicles, and rely on the track for direction.