Should be more possible with Res now I would think?
For example, in the first campaign mission you can find your motorcycle to get to Lipany (or whatever) or you could catch the bus.
Maybe a train can be made using the bus model (enough passengers, arranged in the right way, etc) and then a new road system could be made that's exactly like normal road segments but textured like tracks. Then you use the busstop system in REs for you train station stops. If you make the tracks realistically straight and on flat land, there shouldn't be too many problems.
Finally you could make the tracks actual objects to ensure the effect that one portion of track is destroyed for one reason or another, the train will spin out of control when it nears. (could do a domove random position type command) and then it could explode, or at least crumple after it derails for a few seconds.
Wouldn't look entirely realistic but it may work.
If I knew how to do all this I would and maybe you addon people know why such an idea may not be possible. Just thought I throw a few ideas into the arena...
M