49 U.S.C. § 11122

(a) The regulations of the Board on car service shall encourage the purchase, acquisition, and efficient use of freight cars. The regulations may include— (1) the compensation to be paid for the use of a locomotive, freight car, or other vehicle; (2) the other terms of any arrangement for the use by a rail carrier of a locomotive, freight car, or other vehicle not owned by the rail carrier using the locomotive, freight car, or other vehicle, whether or not owned by another carrier, shipper, or third person; and (3) sanctions for nonobservance. (b) The rate of compensation to be paid for each type of freight car shall be determined by the expense of owning and maintaining that type of freight car, including a fair return on its cost giving consideration to current costs of capital, repairs, materials, parts, and labor. In determining the rate of compensation, the Board shall consider the transportation use of each type of freight car, the national level of ownership of each type of freight car, and other factors that affect the adequacy of the national freight car supply.