Any religious organization bus may be equipped with a 4-lamp flashing signal system having unison flashing amber lamps, 2 at the front and 2 at the rear of the bus, mounted as high and as widely spaced laterally on the same level as is practicable. If this equipment is installed, each lamp must be a sealed beam at least 5-1/2 inches in diameter and have sufficient intensity to be visible at 500 feet in normal sunlight; the system shall be actuated only by means of a manual switch; and there shall be a device for indicating to the driver that the system is operating properly or is inoperative.
(ILCS Ch. 625, Act 5, § 12-901) Penalty, see § 70.999