No motor carrier subject to this chapter shall change, suspend, or annul any individual rate, joint rate, fare, charge, or classification for the transportation of passengers or property except after thirty days' notice to the commission and the public, which notice shall plainly state the changes proposed to be made in the schedule then in force and the time when the changed rates or charges shall go into effect. The commission may enter an order suspending the proposed rate and prohibiting such motor carrier from putting such proposed new rate into effect pending the hearing and final decision of the matter, in which case the proposed new rate shall stand suspended until it is determined by the commission whether or not the same is just or reasonable. The proposed changes shall be shown by printing new schedules, or shall be plainly indicated upon the schedules in force at the time, and kept open to public inspection: Provided, however, That the commission may, in its discretion, and for good cause shown, allow changes upon less time than the notice herein specified, or may modify the requirements of this section in respect to publishing, posting and filing of tariffs, either by particular instructions or by general order.
Whenever there shall be filed with the commission any schedule stating a change in the rates or charges, or joint rates or charges, or stating a new individual or joint rate or charge or joint classification or any new individual or joint regulation or practice affecting any rate or charge, the commission shall have authority, either upon complaint or upon its own initiative without complaint, to enter upon a hearing concerning the propriety of such rate, charge, classification, regulation or practice; and, if the commission so orders, it may proceed without answer or other form of pleading by the interested parties, but upon reasonable notice, and pending such hearing and the decision thereon the commission, upon filing with such schedule and delivering to the motor carrier affected thereby a statement in writing of its reasons for such suspension, may suspend the operation of such schedule and defer the use of such rate, charge, classification, regulation or practice, but not for a longer period than one hundred and twenty days beyond the time when such rate, charge, classification, regulation or practice would otherwise go into effect; and after full hearing, whether completed before or after the rate, charge, classification, regulation, or practice goes into effect, the commission may make such order in reference to such rate, charge, classification, regulation or practice as would be proper in a proceeding initiated after the rate, charge, classification, regulation or practice had become effective: Provided, That if any such hearing cannot be conducted within the period of suspension, as above stated, the commission may in its discretion extend the time of suspension for a further period, not exceeding six months. At any hearing involving a rate sought to be increased or involving the change of any fare, charge, classification, regulation or practice, the burden of proof to show that the increased rate or proposed increased rate, or the proposed change of fare, charge, classification, regulation or practice, is just and reasonable, shall be upon the motor carrier making application for such change. When in any case pending before the commission all evidence shall have been taken, and the hearing completed, the commission shall, within three months, render a decision in such case.
The commission shall prescribe such rules and regulations as to the giving of notice of a change in rates as are reasonable and are deemed proper in the public interest.