(b) The provisions of subdivision (a) or (e) do not apply to a commercial vehicle if a variation from the requirements of subdivision (a) or (e) is reasonably necessary to accomplish the loading or unloading of merchandise or passengers on, or from, such vehicle and while anything connected with such loading, or unloading, is being executed.

This subdivision shall not be construed to permit any vehicle to stop or park upon a roadway in a direction opposite to that in which traffic normally moves upon that half of the roadway on which such vehicle is stopped or parked.

(c) Notwithstanding the provisions of subdivision (b), local authorities may, by ordinance, prohibit commercial vehicles from stopping, parking, or standing on one side of a roadway in a business district with the wheels of such vehicle more than 18 inches from the curb. The ordinance shall be effective only if signs are placed in the areas to which it is applicable clearly indicating the prohibition.

(d) This section does not apply to vehicles of a public utility when such vehicles are being used in connection with the operation, maintenance, or repair of facilities of the public utility or are being used in connection with providing public utility service.

(e) Upon a one-way roadway, vehicles may be stopped or parked as provided in subdivision (a) or with the left-hand wheels parallel to and within 18 inches of the left-hand curb, except that motorcycles, if parked on the left-hand side, shall have either one wheel or one fender touching such curb. Where no curb or barriers bound any such one-way roadway, parallel parking on either side is required unless otherwise indicated.

The provisions of this subdivision shall not apply upon the roadways of a divided highway.