It shall be unlawful for any person to operate a motor vehicle on any street, drive, alley, parking lot, playground, or other place on property owned by any school system of the city or county in violation of any posted traffic or parking regulations. Provided, however, that the provisions of this section shall only be in force and effect during that period of time when the school upon which said violation occurs is in regular session and from thirty minutes prior to the beginning of said regular session until thirty minutes after the end of said regular session. Provided further, however, that the provisions of this section shall not prohibit such other and additional regulations as may be provided under the provisions of 9-117 which from time to time may be in force and effect (Ord. #662, 06/04/87).