No limitation imposed by this act shall in any wise apply to or in any way limit any levy which is authorized by statute for the purpose of creating sinking and interest funds necessary to liquidate at maturity the principal and interest of any indebtedness authorized by law or for the payment of any final judgment; nor shall any provision of this act apply to or in any way limit special taxes levied by ordinance in any city. And nothing in this act shall be construed to limit the levy provided by any special act heretofore passed for the construction of roads, and under which any county is now operating.