The City Council, may, by resolution, set aside and post any street, alley, public way or portion thereof for the parking of any particular kind or class of vehicle, and where the parking of vehicles has been prohibited by resolution, no vehicle prohibited from parking thereon shall stand or be parked adjacent to the curb of said street, alley, public way or portion thereof, longer than a period of time necessary to load and unload freight or passengers. The placement of no parking or restricted parking signs shall be prima facie evidence of the restricting resolution.