The most common rail currently used is 141 AREMA with a height of 7-7/16". There are over 20 rails still used in the US (9 still in production) Outside of the Class 1 railroads 115 AREMA is very...
there is track width (measured from mid rail to mid rail) and track gauge (measured from inside rail to inside rail. As that is the most important size of track, that is normally the distances...