I've noticed in the recent patch for dayz that some of the tracks where updated to a point where most of the lines are cleared and that train cars that used to be on the main line now are on side tracks. I know it sounds crazy to wonder about but is it possible trains could be coming in a much later update to the game? Like even if they are not the ones we see in game, say like steam trains that require coal and water for them to run on. This way parts and fuel would be probably easier to work with and find in game? Idk, this is just an idea that me and my friends cooked up, hope the devs at least take the idea in a little.
