I recently finished laying out the signals for AI traffic on the main lines. I used dozens of "Trigger Multiple Signal Rule".
By the way . . . THANK YOU MAGGS for this Rule !! (***** five stars)
I found this signal tutorial to be extremely helpful.
http://www.trains.0catch.com/Signalling Crossing Tracks and Double Track Junctions.pdf
My route is split in 3 pieces. I started signaling the main route which has trains coming and going through 5 double track Portals on the route. 4 of the 5 Portals are sending 50% of their roster of trains to one portal. So a 6 track exchange area where all the AI trains sort themselves out to their destination tracks gets very congested. A train comes through every few minutes. It took a few weeks to get all the AI trains to behave. Now it runs for hours without any AI on a "stand-still" or any of them backing up for miles. AIs are impatient . . . but will behave if the signals are set up properly.
In working on signaling here are some snags that I ran into that needed to be solved.
1. Setting up train priority : 2 methods.
Method 1 - Use TMS Rule
In the interest more prototypical train movement, you will need to set lots of triggers.
The Trigger spacing is dependent on the SHORTEST train to be driven on the route under AI operation. In my case, that is a commuter train with 6 cars and a loco. I used the 6 car length as my trigger spacing.
Remember that while if ANY of the triggers attached to a signal(s) is under a train, the signal is RED. BUT, if the Triggers are too far apart, there will be short instances when the signal will turn green. The AI train will USUALLY stop about a car length before the red signal . . . but not always. The instance of green signal might be enough to pass the signal and cause a collision. Its happened to me.
Example: A user driven train is coming out of an industry onto the Mainline. The Mainline speed is 60mph. You want any approaching AI train to give you enough advance notice of his approach. So my signal is controlled by many Triggers on the main line. The actual number depends of the shortest train on the main line. So, if I don't have a yellow or green on my signal, there is an approaching train on the main line close enough to hold me back. The signal will change to proceed after the train has passed.
Method 2 : not so reliable
AI train can HOLD a junction for his use from a very long distance away. You can just use an "invisible junction" in his path to limit WHERE he is allowed to HOLD his NEXT junction. In the example above, the AI's NEXT junction is the one you need to get on the main line.
It is "not so reliable" because, if you already started to proceed on to the main line with a heavy train, but the signal turns red just as you past it, can you stop your train? If you place your signal too far from the junction, An AI train can seize the junction before you are over it. Potential for collision.
2. You may run into a situation where you want ONE signal to be activated more than one TMS Rule . . . which can't be done.
A work-around solution is to place a dwarf signal in the same place as a standard "04" signal. The signals are supposed to be a certain minimum distance apart. I found out that the second signal works with the TMS rule, AND the AI will not proceed until BOTH signals are clear.
It took a lot of "trial and error" and "experiments" to get the AIs behaving.
Hope this helps someone.
