Link to Bob Redman's article "Politics in the Union Army at the Battle of Chattanooga," (with maps, photos). Also, Google Map.

Bob Redman has some long articles on the Battle of Chattanooga, including some interesting comments on Sherman's comment about poor maps of the tunnel area on Lightfoot Mill Road. His theory is that the maps weren't poor at all (he gives examples), and that Sherman was covering for his own incompetence in stopping short of his objective, the tunnel.

Politics in the Union Army at the Battle for Chattanooga (Link)
Bob Redman article, "Politics in the Union Army at the Battle for Chattanooga: George H. Thomas - the consumate anti-politician," at AOTC.net (includes historic maps, modern map with diagram, and modern photos of the general battle area (unable to get close view due to private-property restrictions) and rather neglected park:
http://www.aotc.net/article1.htm

Google Map: Battle of Chattanooga; Lightfoot Mill Road and Tunnel Area
My Short URL to Google Map: http://bit.ly/GoogleMap-Lightfoot-Mill-Rd-Tunnel-Area

GOOGLE'S SHORT URL TO SAME MAP
https://goo.gl/maps/L71hQsZoW292

Same Redman article on another site:
American Civil War: George H. Thomas and Politics in the Union Army at the Battle for Chattanooga
Bob Redman
http://www.americancivilwar.com/authors/BobRedman/article1.htm