All restricted vehicles shall be driven only upon the state highways, including the interstate system, within the city limits, deviating therefrom only when necessary to traverse another street or streets when necessary for loading, unloading or servicing, and then only departing from the state highway route at the nearest reasonable and practical point; provided, however, that no such vehicle shall be loaded, unloaded or serviced upon any street or part of a street if there is usable off-street loading, unloading or servicing space available. In so doing, no vehicle may be positioned upon the roadway so as to constitute a hazard to vehicular or pedestrian traffic. (Ord. 2-21-84A (part); Code 1975 § 11-307(2))