The driver of any commercial vehicle, including a truck or tractor with a registered gross weight in excess of 7,000 pounds, or any semitrailer, tractor, or trailer, is prohibited from parking such vehicle on a street in a residence district except in an emergency such as delivery of construction equipment and materials to a building site, or temporarily during such time as such vehicle is being loaded or unloaded.
('75 Code, § 15-126) Penalty, see § 72.99(A)