Except with the approval of the State Fiscal Accountability Authority, the Department of Transportation shall not let any highway construction contracts unless reserves for such contracts shall have been provided for out of either (a) current balances in the state highway fund, (b) federal aid obligated for such contracts or (c) estimated revenue balances accruing during the period in which payments are to become due on such contracts; it being the intention of the General Assembly by the enactment of the section that the department shall not let any highway construction contracts which are contingent upon additional tax revenue legislation or upon receipt of the proceeds of anticipated bond sales for the payment of such contracts, unless the amount of highway construction contracts proposed to be let shall receive the approval of the State Fiscal Accountability Authority.