The governing body of any such county or counties issuing bonds under the provisions of this article is hereby authorized to fix and to revise from time to time tolls for transit over such bridges, to charge and collect the same, and to contract with any person, partnership, association, or corporation desiring the use of any bridge, its approaches, appurtenances, or any part thereof for placing thereon water, gas, oil pipelines, telephone, telegraph, electric light or power lines, railroad or street railway tracks, or for any other purpose, and to fix the terms, conditions, rates, and charges for such use. Such tolls shall be so fixed and adjusted, in respect of the aggregate of tolls from the bridge or bridges for which a single issue of bonds is issued, as to provide a fund sufficient with other revenues of the bridge or bridges, if any, to pay (a) the cost of maintaining, repairing, operating such bridge or bridges, and collecting tolls, and (b) the bonds and the interest thereon as the same become due. Such tolls shall not be subject to supervision or regulation by any state commission, board, bureau, or agency, except such bureau or agency that might participate in the financing of the cost of any such bridge. The tolls from the bridge or bridges for which a single issue of bonds is issued, except such part thereof as may be required to pay the cost of maintaining, repairing, and operating the bridge or bridges and to provide such reserves therefor as may be provided in the resolution authorizing the issuance of the bonds or in the trust indenture, shall be set aside at such regular intervals as may be provided in such resolution or such trust indenture, in a sinking fund which is hereby pledged to, and charged with, the payment of (1) the interest upon such bonds as such interest shall fall due, (2) the principal of the bonds as the same shall fall due, (3) the necessary fiscal agency charges for paying principal and interest, and (4) any premium upon bonds retired by call or purchase as herein provided. The use and disposition of such sinking fund shall be subject to such regulations as may be provided in the resolution authorizing the issuance of bonds, or in the trust indenture, but, except as may otherwise be provided in such resolution or trust indenture, such sinking fund shall be a fund for the benefit of all bonds without distinction or priority of one over another. Subject to the provisions of the resolution authorizing the issuance of bonds or of the trust indenture, any moneys in such sinking fund in excess of an amount equal to one year’s interest on all bonds then outstanding may be applied to the purchase or redemption of bonds. All bonds so purchased or redeemed shall forthwith be cancelled and shall not again be issued.