On a school day when school children are present and so close thereto that a potential hazard exists because of the close proximity of the motorized traffic, no person shall drive a motor vehicle at a speed in excess of 20 miles per hour while passing a school zone or while traveling on a local, county, or State roadway on public school property or upon any public thoroughfare where children pass going to and from school.
For the purpose of this Section, a school day begins at 6:30 a.m. and concludes at 4 p.m.
This Section shall not be applicable unless appropriate signs are posted upon streets and highways under their respective jurisdiction and maintained by the Department, township, county, park district, city, village or incorporated town wherein the school zone is located. With regard to the special speed limit while passing schools, such signs shall give proper due warning that a school zone is being approached and shall indicate the school zone and the maximum speed limit in effect during school days when school children are present.
625 ILCS 5/11-605