(a) If the commission determines that the mobility needs of a region of this state could be most efficiently and economically met by jointly operating two or more toll projects in that region as one operational and financial enterprise, it may create a system composed of those projects. The commission may create more than one system in a region and may combine two or more systems in a region into one system. The department may finance, acquire, construct, and operate additional toll projects in the region as additions to or expansions of a system if the commission determines that the toll project could most efficiently and economically be acquired or constructed if it were part of the system and that the addition will benefit the system.(b) The revenue of a system shall be accounted for separately and may not be commingled with the revenue of a toll project that is not part of the system or with the revenue of another system. Added by Acts 2005, 79th Leg., Ch. 281 (H.B. 2702), Sec. 2.39, eff. June 14, 2005.