My first thought is two stairways angled, in a pyramid fashion, the station capping it. Dramatic, but a hazard for folks to cross the rails, etc.
Inside the loop(s) looks clear enough for a "switchback" or square staircase and maybe an elevator. (Gotta have stairs first 
)
Charlie's Glass Elevator do anything for you ? (Willy Wonka)
An operating elevator? Wouldn't be too hard, the door action would be the biggest challenge imo. Up & down; easier.
Premade wood dollhouse stairs. Hobby Lobby, etc. No detail, just zig zag cut wood. They come in different scales. (I think we made this set though)
