(a) Whenever an illuminated red or yellow signal is used in a traffic
sign or signal it shall require obedience by vehicular traffic as
1. Flashing red (stop signal). When a red lens is illuminated with
rapid intermittent flashes, drivers of vehicles shall stop before
entering the nearest crosswalk at an intersection or at a limit line
when marked, or, if none, then before entering the intersection, and
the right to proceed shall be subject to the rules applicable after
making a stop at a stop sign.
2. Flashing yellow (caution signal). When a yellow lens is illuminated
with rapid intermittent flashes, drivers of vehicles may proceed
through the intersection or past such signal only with caution.
(b) This section shall not apply at railroad grade crossings. Conduct
of drivers of vehicles approaching railroad grade crossings shall be
governed by the rules as set forth in Section 11-701 of this act.