(a) For the purpose of providing funds to enable the authority to pay at their respective maturities and due dates the principal of and interest on the obligations that may be issued by it under this article at any time after March 1, 2014, there hereby is irrevocably pledged and appropriated so much as shall be necessary for the purpose of the state's share of net gasoline tax proceeds.

(b) In addition, for the purpose of providing funds to enable the authority to pay at their respective maturities and due dates the principal of and interest on the obligations that may be issued by it under this article, there hereby is irrevocably pledged and appropriated each year all federal aid funds for federal aid projects to be received by the State Department of Transportation from the United States government to the extent that such funds may be required to pay the principal of and interest on such obligations. All federal aid funds for federal aid projects received by the State Department of Transportation from the United States government during each such federal fiscal year shall be held in trust by the state and applied to the extent required to the payment of the principal of and interest on the obligations authorized to be issued under this article.

(c) All moneys hereby appropriated and pledged shall be paid into the State Treasury and shall constitute a sinking fund which shall be held in trust to be used to pay the principal of and interest on the obligations; provided, however, that the pledge of the state’s share of net gasoline tax proceeds shall be on parity with the pledge contained in Section 23-1-181 to secure obligations issued by the Alabama Highway Finance Corporation. As security for the payment of the principal of and interest on the obligations issued under this article, the authority is authorized to pledge the proceeds of the appropriation and pledge provided for in this section. All pledges made by the authority shall take precedence among themselves in the order of the adoption of the resolutions making such pledges, except as may be otherwise provided in such resolutions. The State Department of Transportation is hereby authorized and directed to set aside the first moneys received out of the revenues pledged hereunder in each fiscal year and deposit the same in the sinking fund provided for in this subsection until there shall have been accumulated therein an amount at least sufficient to pay the principal of and interest on the obligations issued by the authority hereunder which mature, are subject to mandatory redemption or otherwise become due during such fiscal year.