(1) No vehicle may stop or park for any purpose or length of time other than for the loading or unloading of passengers in any place marked as a passenger curb loading zone during the hours when the regulations applicable to such loading zones are effective, and then only for a period not to exceed three minutes, provided the driver remains with the vehicle, and the vehicle's engine remains running.

(2) No vehicle may stop or park for any purpose or length of time other than for the expeditious loading or unloading of materials in any place marked as a freight curb-loading zone during hours when the provisions applicable to such zones are in effect. In no case shall the stop for loading and unloading of materials exceed thirty (30) minutes.

(3) The driver of a passenger vehicle may stop at a place marked as a freight curb loading zone for the purpose of and while actually engaged in loading or unloading passengers when such stopping does not interfere with any vehicle which is waiting to enter or about to enter such zone for the purpose of loading or unloading freight, provided that the driver remains with the vehicle, and the vehicle's engine remains running.