(a) If the commission determines that the provision of rail transportation services would be most efficiently and economically met by jointly operating two or more rail facilities as one operational and financial enterprise, it may create a system composed of those facilities.
(b) The commission may create more than one system and may combine two or more systems into one system.

(c) The department may finance, acquire, construct, and operate additional rail facilities as additions to and expansions of the system if the commission determines that the facility would most efficiently and economically be acquired and constructed if it were a part of the system and that the addition will benefit the system.
(d) The revenue of a system shall be accounted for separately and may not be commingled with the revenue of a rail facility that is not part of the system.