I have spent a few days wandering around the Flagstaff and also the stretch between Ash Fork and Prescott exploring "lost" rights of way. Some great information here, and also contained in the follow ups.
I have enjoyed the "bridges" that were built by the logging rail roads, sometimes a pile of rocks, other times rough wooden structures. If any of you are interested in my photos in a somewhat unorganized state, my flickr album is here: [
www.flickr.com]
It contains some Peavine shots south of Ash Fork, current BNSF, and lots of shots of railroad grades around the national forests. Thanks for the various maps, they are great!