The governing body of any county is authorized to provide by resolution for the issuance of bridge revenue refunding bonds of such county for the purpose of refunding any bridge revenue bonds or any other indebtedness of said bridge of the county which were issued before April 22, 1941, or may be issued under the provisions of sections 39-860 to 39-866, and amendments thereto, and may be outstanding. The issuance of such bridge revenue refunding bonds, the maturities, and other details thereof, the rights of the holders thereof, and the duties of the county in respect to the same, shall be governed by the provisions of said sections, insofar as the same may be applicable, and by the following provisions: (1) That no bridge revenue refunding bonds shall be delivered in an amount exceeding the amount necessary to provide funds sufficient for refunding the principal amount of outstanding bridge revenue bonds and accrued interest thereon, together with an amount required to produce the sum necessary to provide the redemption premium on any outstanding bonds to be refunded and any expenses incidental thereto; and (2) the rates of tolls, to be charged for the use of the bridge or bridges acquired from the proceeds of the bridge revenue bonds to be refunded, shall be so fixed and adjusted as to provide a fund sufficient to pay the interest on and the principal of such bridge revenue refunding bonds as the same shall become due, and to provide an additional fund to pay the cost of maintaining, repairing, and operating such bridge or bridges. Any such tolls shall be continued until such bridge revenue refunding bonds and the interest thereon shall be paid, or provision made for their payment.