R.I. Gen. Laws § 24-12-27
Tolls shall be so fixed and adjusted in respect of the aggregate of tolls from the project or projects or the portion or portions thereof in connection with which bonds shall have been issued under the provisions of this chapter as to provide a fund sufficient with other revenues, if any, to pay (1) the cost of maintaining, repairing, and operating the project or projects or portion or portions thereof and (2) the principal of and the interest on the bonds as the principal and interest shall become due and payable, and to create reserves for such purposes; provided, however, that the authority shall establish commutation rates for traffic over the Mount Hope Bridge by all vehicles, which rates shall not be in excess of the commutation rates in effect for vehicles on January 1, 1960. Tolls shall not be subject to supervision or regulation by any commission, board, bureau or agency of the state or of any municipality or other political subdivision of the state.
R.I. Gen. Laws § 24-12-27