The Council is authorized, by published resolution, to prohibit the operation of trucks or other commercial vehicles or to impose limitations as to weight thereof on any highway, street, alley or roadway within the city whenever any such highway, street, alley or roadway, by reason of deterioration, rain, frost, snow or other climactic conditions, will be seriously damaged or destroyed, unless the use of vehicles thereon is prohibited or the permissible weights thereof reduced. Prohibitions or restrictions shall not be effective unless and until signs are posted on the designated highways, streets, alleys or roadways.
(`89 Code, § 122.040)