If any fence, wall or hedge shall have been required for any parking area under subparagraph d of this subsection, then the fence, wall or hedge shall be protected by a concrete curb or bumper guard, or the equivalent, which shall run parallel to the fence, wall or hedge, be at least five (5") inches in height above the paved surface adjacent to the fence, wall or hedge, and be sufficient distance therefor to protect the fence, wall or hedge from the impact of motor vehicles. Utility poles or railroad ties shall not be used to meet required curbing or bumper guards;