The Board of Commissioners determines that it is necessary to limit the weight load of all vehicles using the public highways and bridges, and to provide for posting load limits on the public highways and bridges and to prohibit the use of the roads and bridges to all vehicles which exceed the posted limits unless prior approval of routes and protection for roads and bridges is specifically given by the Superintendent of the Jasper County Highway Department, or other officials who may be designated by the Board of Commissioners. [Code 1988 § 116.01.]