I think the devs will only make it easy for modders to put I.E. new train models in the game.
To change the behaviour of trains you need to mess about with the code I think. I doubt it that the devs will make it ‘easy’ for someone to change the code, just because they probably don’t expect anyone to change the AI’s behaviour.
I think that, if you’d really want what you just said, you’ll have to ask the devs themselves to make difficulty levels just like SM RailRoads has for example. It had an ”easy” mode, a ”medium” mode and a ”hard” mode.
In easy trains would just become ghosts and go trough each other,
in medium one train would stop and the other would go trough the stopped train,
on hard trains couldn’t go trough each other and you’d need to make sidings (which was kind of impossible due to the moronic and old AI system [”Oh, there’s a train on that track, but not on this track. Let’s go to the track with the train on it :DDDD”]).
A ”Super-Hard” mode in TF would be nice. I’m not a big fan of trains just doing a 180 and going the other way, just like you’d like a very complex shutter system.
And maybe if you want a super complex and complicated AI system you could try A-Train. I literaly gave up on that game. It was so complex that I didn’t even understand it, but on the other hand, I loved it how train drove backwards and you could place them on sidings.
But as I said,I think it’s best to ask the devs for a complex system instead of a modder, since they know how the code works (I hope :P).