It shall be unlawful for the driver of a vehicle to stop, stand or park said vehicle for a period of time longer than is necessary for the expeditious loading or unloading of passengers or the unloading and delivery or picking up and loading of materials in designated loading zones. In no case shall the stop for loading and unloading of materials exceed thirty (30) minutes. The members of the Woodridge Police Department may direct the manner of taking up or setting down passengers or loading or unloading of materials in designated loading zones. (1976 Code §19-295)