Tennessee Code Title 65. Public Utilities and Carriers § 65-6-205

(a) The minimum distance between the center lines of parallel standard gauge tracks shall be fourteen feet (14′) except as provided in this section.

(b) The center line of any standard gauge ladder track, constructed parallel to any other adjacent track, shall have a clearance of not less than eighteen feet (18′) from the center line of such other track.

(c) The minimum distance between the center lines of parallel team, house and industry tracks shall be thirteen feet (13′).

(d) Tracks constructed prior to April 13, 1949, may be maintained at such clearance as was lawful at the time of construction.