The other day I came across Hmmsim in the apple app store, it is a free driving simulator and I have tried it on an ipad mini retina, the graphics are excellent and it runs very smoothly.
It only comes with a fairly short route(another line coming soon) but gives you enough chance to see what it can do, there are no other moving trains and I think the signalling is fixed so every run will be the same, there is not a timetable(though there will be in a later version) so it's a case of arriving at a station, opening doors, close doors and depart when you want, there is no external view yet(coming soon).
You can add bve routes into it, these have to be converted first with a utility, I have tried a few but did not have very good results, maybe I was not converting properly, may have another go soon.
If you want to give it a go look here-
http://jeminie.kr/hmmsim/eng/intro.html