It shall be unlawful for the operator of a vehicle to stop, stand or park a vehicle in any place marked as a loading zone other than for the expeditious loading or unloading of passengers, and in no case for a period of more than three (3) minutes, or for the unloading and delivery or pick up and loading of materials, and in no case shall the stop for loading and unloading of materials exceed thirty (30) minutes. The Director of Public Works may determine the location of loading zones, and also the hours when the provisions of this section shall be applicable, subject to the approval of the Village Board. (1976 Code § 41.14)