I printed this out for further study tomorrow. Sounds doable, but will have to do a bit of thinking about it.
One question, have you considered using something like GRJ's train detection relays? That might be a good input to the Arduino for train detection. I have some I am going to use for similar stuff on my layout. If not did you have something else in mind? Apologies if this has already been discussed here.
Also, I am not sure what a Lionel 152 is, will have to look that one up and see.
Maybe I should also just go back and read the whole thread here. Play a little catch up.
As Arnold said, "I'll be back"!