Barry,
Thanks much for the info, and now that I do not use any AIU's any more for my switches, I do believe I can get away with powering dual TIU's from the one RS 18/24 power supply, if the emergency stop will carry thru both TIU's, when powered from the same RS power supply. I did have to give up the scenes and the routes not having any AIU's, but on my smaller Christmas layouts I was will to eliminate them also.
Thanks again Barry I appreciate the education once again.
PCRR/Dave