I've heard from another post that there wont be any air vehicles exept if a dlc to another island is made.

I know, but standing on a moving train is still dangerous even if it's computer controlled. At least i think so.

Ok, i didnt expect that.

I think train surfing would be a great thing to be able to do. If you train surf you don't have to pay for tickets, but it comes with a risk, if you get spotted or fall of the train that you can get arrested, major injuries or even death.