Tennessee Code Title 65. Public Utilities and Carriers § 65-6-202

(1) “Height” of a freight car is the distance between the top of the rail and the top of the running board;

(2) “Overhead clearance” is the vertical distance between the two (2) rails from the level of the top of the highest rail to a structure or obstruction above on tangent track and from the mean level of the two (2) rails on curved track;

(3) “Side” of a freight car is that part or appurtenance of the car at the maximum distance measured at right angles from the center line of the car;

(4) “Side clearance” is the shortest distance from the center line of track to a structure or obstruction at the side of track up to a distance of fifteen feet (15′) and six inches (6″) from the top of the rail; and

(5) “Width” of a freight car is twice the distance from the center line to the side of a car as defined in this section.