I hadn't looked at the Silverton Railway maps too much until you mentioned it. The loop at Chattanooga is interesting and something that I didn't know about. It will certainly be something new to check out on my next trip. The one long spur is also interesting. It seems like that would have been a significant grade if I remember the lay of the land correctly. I would have though that it would have to be angled further east for a more gentle grade.
These maps for the Silverton are something that I have wanted for a few years now. Up until this point I had only found small scale maps that weren't very accurate and rather useless for overlays. Unfortunately they were done in the later years and there isn't coverage beyond Red Mountain.
Dave