(c) Pilots are not required if the movement is on a section of track with an average grade of less than 1% over 3 continuous miles, and

(1) The track is other than a main track;

or

(2) The maximum distance the locomotive or train will be operated does not exceed one mile;

or

(3) The maximum authorized speed for any operation on the track does not exceed 20 miles per hour;

or

(4) Operations are conducted under operating rules that require every locomotive and train to proceed at a speed that permits stopping within one half the range of vision of the locomotive engineer.