Subject to the restrictions on expenditures imposed by Code Section 32-5-23, the State Public Transportation Fund shall be expended by the department in the following order:

(1) To pay the rentals on lease contracts entered into pursuant to the authority of the Constitution of Georgia;

(2) To pay into the State of Georgia Guaranteed Revenue Debt Common Reserve Fund the amount of the highest annual debt service requirements for an issue of guaranteed revenue debt for public road projects initiated pursuant to Code Section 32-10-67, upon its issuance, when the guarantee of the specific issue has been authorized by an appropriation of moneys governed by Article III, Section IX, Paragraph VI(b) of the Constitution and the appropriation meets the requirements for such debt as provided by Article VII, Section IV, Paragraph III(b) of the Constitution;

(3) To pay the costs of operating the department and for any emergencies or unusual situations;

(4) To pay the costs necessary to comply with the conditions of federal-aid apportionments to the state for the planning, surveying, constructing, paving, and improving of the public roads in Georgia;

(5) Next, a sum equal to at least 15 percent of the State Public Transportation Fund, said sum to be used as follows:

(A) One-third to pay all or part of the costs of the planning, surveying, constructing, improving, paving, and completing public roads not on the state highway system;

(B) One-third to pay all or part of the costs of planning, surveying, constructing, improving, and paving public roads on the state highway system; and

(C) The remaining one-third to pay all or part of the costs of planning, surveying, constructing, reconstructing, paving, and improving the public roads of Georgia determined by the department to be most in need of such work; and

(6) After the requirements set out in the foregoing provisions of this Code section have been met, the remainder of the State Public Transportation Fund to be expended to pay the costs of maintaining, improving, constructing, and reconstructing the public roads of the state highway system, for maintaining roads within and leading to state parks, and for constructing public roads by department forces.