(A) For the purpose of this section,
SCHOOL means the following entities:
(1) A public or private primary or secondary school.
(2) A primary or secondary school operated by a religious institution.
(3) A public, private, or religious nursery school.
(B) For the purpose of this section, a SCHOOL DAY begins at 6:30 a.m. and concludes at 4:00 p.m.
(C) 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 upon any public thoroughfare where children pass going to and from school.
(D) This section shall not be applicable unless appropriate signs are posted upon streets wherein the school zone is located. With regard to the special speed limit while passing schools, 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. Nothing in this chapter shall prohibit the use of electronic speed-detecting devices within 500 feet of signs within a special school speed zone indicating the zone, as defined in this section, nor shall evidence obtained thereby be inadmissible in any prosecution for speed, provided the use of the device shall apply only to the enforcement of the speed limit in the special school speed zone.
(625 ILCS 5/11-605(a)) Penalty, see § 70.99