Also I wonder how does the train movement affect ventilation. I recall the mountain train tunnels in Italy. Since the tunnels are just wide enough, the trains act as pistons, pushing and pulling air in and out of the tunnels. I recall experiencing pretty strong wind coming out of the tunnel prior to the train emerging out of it. I wonder if this is enough to circulate enough air. I'm not expecting an answer, just wanted to share this shower thought. 😄