What are the roads like? Tire size would be my 1st criteria. I think you will endo on a Carryme.
If the trains aren't crowded then a 20" fat tired bike would probably be best since it will ride better; Tern, Dahon, BF, etc.
If the train is packed then a Brompton rides like a lawn chair, but its small fold and the frame is steel/durability. Birdy, side folders, and 20" are too wide for a crowded train IMO; you can't stand over the folded bike so it's like a piece of luggage that others don't want to rub against and you become the jerk taking up the space of 2 people. You can easily stand over a folded Brompton. Strida is good for trains but a weird riding posture. Possibly a Helix can be straddled in a train, but I have no experience with it.
Last edited by ttakata73; 07-20-19 at 01:40 PM.