From the money deposited in the acquisition and construction fund, the treasurer shall transfer to the place or places of payment named in the bonds such sums as are required to pay the interest as it becomes due on all bonds sold and outstanding for the construction of the toll tunnel during the period of actual construction and during the period of six months immediately thereafter. The treasurer shall thereafter transfer from the toll revenue fund to the place or places of payment named in the bonds such sums as are required to pay the interest on the bonds and to redeem the principal thereof as such interest payments and bond redemptions fall due for all bonds issued and sold for the construction or acquisition of the toll tunnel. All funds transferred for the payment of principal or interest on bonds issued for the toll tunnel shall be segregated and applied solely for the payment of such principal and interest.