Ga. Code § 32-10-30
The authority shall have the power and is authorized, at one time or from time to time, to provide by resolution for the issuance of negotiable bonds in a sum not to exceed $484 million in principal amount outstanding at any one time for the purpose of paying all or any part of the cost of any one or a combination of projects; provided, however, that of such authorized amount not more than $150 million of bonds may be issued to finance county road projects, not more than $234 million of bonds may be issued to finance state road projects, and not more than $100 million of bonds may be issued to finance urban road projects. The bonds of each issue shall be dated, shall bear interest as provided for in Code Section 32-10-31, shall be payable in such manner of payment as to both principal and interest as may be determined by the authority from the special funds provided in this article for such payment, shall mature not later than 30 years from the date of issuance, and may be made redeemable before maturity, at the option of the authority, at such price or prices and under such terms and conditions as may be fixed by the authority in the resolution providing for the issuance of the bonds. For the purpose of this Code section, bonds shall not be considered to be outstanding if there shall have been deposited into the sinking fund created for the payment of such bonds amounts sufficient to pay the same, together with the interest thereon as the bonds mature.
OCGA § 32-10-30