It was going clockwise so, circle->square->triangle,
the blue train was going anti-clockwise, also circle->square->triangle,
and the green one clockwise, star->square->triangle
Unfortunately, by the time I realised that it wasn't picking up passengers it was game over. I'd seen the station overcrowding and just allowed the train to get there in it's own time, so when it failed to pick up it just went over the threshold...