Thanks for the replies. I do realize that this is sort of a “much ado about very little” situation. The problem only shows up when I am running a train continuously on the main line (my outer loop) AND at the same time moving a loco across the reversing diagonal that connects the two sides of my inner loop. I had RailPro for a year and a half before I tried this situation, so it is not common to my operations.
By far the easiest solution is to have the loco on the reversing diagonal stop briefly, while I flip the existing DPDT directional switch for the reversing diagonal, then resume its motion. It will continue to go forward because RailPro direction is determined by the setting on the HC-2, not by the track polarity.
This is actually a prototypically realistic solution. The diagonal track has several yard spurs coming off of it. It is realistic that one of those yard turnouts might need to be switched before proceeding through the yard.
BUT, I like to know precisely how things work, and I would like to know how to allow continuous motion of both locos in this situation – even if I decide not to build the fix.
SO, I have been playing with wiring diagrams and switch position situations, and I may post something here when I think I have got it figured out.
BUT, FIRST I HAVE A QUESTION. (I put this in all caps so that you can find the question among my ramblings.) I want to be sure that I understand exactly how the AR-1 works.
When a loco enters or exits an AR-1 isolated block and finds that the polarities of the two blocks are opposite, it quickly flips the polarity of one of the blocks. Am I correct that it always (whenever needed) flips the polarity of the AR-1 block, regardless of whether the loco is entering or leaving the AR-1 block?