Hi John
Thanks for the suggestion about a delay, but my trains are not being emitted from a portal, they all exist on the layout somewhere at startup, and then have their own session rules to allow them to go around the layout realistically. In addition, I have a (now and finally fully automated) 8 train fiddle yard where most of the other trains come through at some point on their travels, and this triggers the relevant consist ahead of it to go out and do its stuff, so that the consits running are changing regularly.
I could not sleep the other night, (not the fault of TS12 I don't think!) and got to thinking about the Priorities system in TS12, so decided to bite the bullet, take out a bunch of track marks, and then set up the two station up and down main lines with suitable priorities.
Guess what, so far it is working a treat !!!!!!!
Not quite sure about the whys and wherefores of it all, but trains seem to adapt very well if they cannot get their selected priority route, but mostly they seem to manage to get it all OK, and now they only need the stopping point for each platform as a track marker to achieve the long sought after and required results.
I hope this may help others trying to do what I have been fighting with. I would certainly advise playing with priorities, especially as you can change them on the fly using the provided "Priorities" rule in the sessions. It is just a shame you do not have more than 1,2 or 3, but hey, they are behaving well right now.
Cheers
Ian