(A)   In the central business district,  when insufficient space is available in the parking lane to accommodate the vehicle preventing parking on the curb, commercial trucks, excluding three-fourths-ton and smaller pickup trucks, may park in the traffic lane adjacent to the parking lane for the sole purpose of immediate and expeditious loading or unloading of merchandise. Such trucks shall be parked in such manner that they will not impede or unreasonably disrupt or interfere with the normal flow of traffic,  nor  shall  such  trucks  be left  unattended  for more than any five-minute period.  Furthermore, such trucks are required to move immediately to allow any vehicle parked on the curb to leave.
   (B)   This privilege of parking in the traffic lane  shall not be exercised in an arbitrary manner and shall not be abused.  Such privilege shall be exercised under the supervision of the Chief of Public Safety and other traffic officers of the city.  Parking in the traffic lane as herein described, for any period of time in excess of 15 minutes in any one location shall constitute a violation of this article and shall be punishable as provided in §§ 72.70 through §§ 72.81. ('84 Code, § 16-107)