Section 157 - Rates, fares and charges; common carriers1. It shall be the duty of every common carrier of passengers to establish, observe and enforce just and reasonable rates, fares and charges, and just and reasonable regulations and practices relating thereto.2. Common carriers of passengers by motor vehicle may establish through routes and joint rates, fares and charges with other such carriers and once established it shall be the duty of all such carrier parties to establish just and reasonable rates, fares, charges, regulations and practices and equitable divisions of revenue.3. All such charges made for any service rendered, or to be rendered by any common carrier of passengers by motor vehicle, shall be just and reasonable, and every unjust and unreasonable charge for such service or any part thereof, is prohibited and declared to be unlawful. It shall be unlawful for any common carrier to make, give or cause any undue or unreasonable preference or advantage to any particular person or to subject any particular person to any unjust discrimination or any undue or unreasonable prejudice or disadvantage in any respect whatsoever.4. Whenever, after a hearing, upon complaint, or in an investigation on the commissioner's own initiative, the commissioner shall determine that any individual or joint rate, fare or charge in effect or proposed to be put into effect by any common carrier or group of common carriers of passengers by motor vehicle or any rule, regulation or practice whatsoever affecting such rate, fare or charge or the value of the service thereunder, is or will be unjust or unreasonable, or unjustly discriminatory, unduly preferential or unduly prejudicial, the commissioner shall determine and prescribe the lawful rate, fare or charge, or the lawful rule, regulation or practice thereafter to be observed.5. The commissioner shall, whenever deemed necessary or desirable in the public interest, after a hearing, upon complaint or upon the commissioner's own initiative, establish through routes and joint rates, fares, charges, regulations or practices, applicable to the transportation of passengers by common carriers and the terms and conditions under which such through routes shall be operated.6. Whenever, after a hearing, upon complaint or upon the commissioner's own initiative, the commissioner shall determine that the divisions of joint rates, fares or charges applicable to the transportation of passengers by common carriers are or will be unjust, unreasonable, inequitable, or unduly preferential or prejudicial as between the carrier parties, the commissioner shall by order prescribe the just, reasonable and equitable divisions thereof. The order of the commissioner may require the adjustment of divisions between the carriers, in accordance with the order, from the date of filing the complaint or entry of order of investigation, or such other date subsequent as the commissioner finds justified and, in the case of joint rates or fares prescribed by the commissioner, the order as to divisions may be made effective as a part of the original order.7. In proceedings to determine the reasonableness of rate or fare levels for a common carrier of passengers or group of common carriers of passengers, the commissioner shall authorize revenue levels that are adequate under efficient management to cover total operating expenses, plus a reasonable profit as determined by the commissioner.