The agency is authorized to enter into agreements with federal agencies for financial assistance for highway purposes, and to award contracts for the construction of these highways whenever the federal funds are available as stated in section 1508 of this title, and any expenditures made shall be chargeable against the advances authorized in section 1508. Provided, however, that as soon as any regular appropriated funds become available, to which the expenditures may properly be charged, the commissioner of finance and management shall charge the expenditures to the regular appropriations thereby restoring the amount of the advance so that it will again become available for future use. (Added 1985, No. 269 (Adj. Sess.), § 1.)