Missouri Laws 300.165 – Flashing signals
1. Whenever an illuminated flashing red or yellow signal is used in a traffic sign or signal it shall require obedience by vehicular traffic as follows:
(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.
2. 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 300.295 of this ordinance.