It is unlawful for any person to drive any traction engine, heavy truck load, other machinery, or heavy vehicles upon or across any bridge or culvert or upon the streets of the city, loaded or otherwise weighing, including such load, to exceed an H-20 loading or as posted on the bridge or culvert by order of the mayor, without first ascertaining the carrying capacity of such bridge or culvert, and taking such action as may be necessary to adequately protect such bridge or culvert so as to carry such unusual weight. (1989 Code: prior code § 15-2-9)