No person shall stop, stand or park a vehicle for any purpose of length of time other than for the expeditious unloading and delivery or pickup and loading of materials, freight or passengers in any place designed as a loading zone during the hours when the provisions applicable to loading zones are in effect. In no case shall the stop for loading and unloading of passengers and personal baggage exceed five minutes, nor the loading or unloading of materials exceed fifteen (15) minutes. (Prior code § 6.060)