It shall be unlawful for any person to ride, or for the owner or operator of any motor vehicle being operated on a street, alley or other public way or place to permit any person to ride on any portion of such vehicle not designated or intended for the use of passengers. This section shall not apply to persons engaged in the necessary discharge of lawful duties nor to persons riding in the load-carrying space of trucks.
(`83 Code, § 9-121) Penalty, see § 10.99