(a) The principal of, interest on, and any redemption premium on bonds issued by an authority are payable solely from:
(1) the revenue of the turnpike project or system for which the bonds are issued, including tolls pledged to pay the bonds;
(2) payments made under an agreement with the commission or a local governmental entity as provided by Subchapter G;
(3) money derived from any other source available to the authority, other than money derived from a turnpike project that is not part of the same system or money derived from a different system, except to the extent that the surplus revenue of a turnpike project or system has been pledged for that purpose; and
(4) amounts received under a credit agreement relating to the turnpike project or system for which the bonds are issued.
(b) Bonds issued under this chapter do not constitute a debt of the state or any of the counties of an authority or a pledge of the faith and credit of the state or any of the counties. Each bond must contain on its face a statement to the effect that the state, the authority, and the counties of the authority are not obligated to pay the bond or the interest on the bond from a source other than the amount pledged to pay the bond and the interest on the bond, and neither the faith and credit and taxing power of the state or the counties of the authority are pledged to the payment of the principal of or interest on the bond.
(c) An authority may not incur financial obligations that cannot be paid from revenue derived from owning or operating the authority’s turnpike projects and systems or from other revenue provided by law.