No person shall stop, stand, or park a vehicle other than a bus in a bus stop, or other than a taxicab in a taxicab stand when any such stop or stand has been officially designated and appropriately signed, except the driver of a passenger vehicle may temporarily stop there for the purpose of, or while actually engaged in, loading or unloading passengers when such stopping does not interfere with any bus, or taxicab waiting to enter or about to enter such stop or stand.