(1) Unless the Arkansas Department of Transportation otherwise orders, no public utility shall make any change in any rate duly established under this act except after thirty (30) days' notice to the department. This notice shall plainly state the change proposed to be made in the rates then in force and the time when the changed rates will go into effect.
(2) The utility shall also give notice of the proposed changes to other interested parties as the department in its discretion may direct.
(3) The department, for good cause shown, may allow changes in rates without requiring the thirty (30) days' notice, under such conditions as it may prescribe. All allowed changes shall be immediately indicated upon its schedules by the public utility.