Every bus used for the principal purpose of transporting school children shall be equipped with a warning device of such type as may be prescribed by the State Board of Education after consultation with the Superintendent of State Police. Such a warning device shall indicate when such bus is either (i) stopped or about to stop to take on or discharge children, elderly individuals, or individuals with mental or physical disabilities or (ii) stopped or about to stop for another such bus, when approaching from any direction, that is stopped or about to stop to take on or discharge any such individual. Such warning device shall be used and in operation for at least 100 feet before any proposed stop of such bus if the lawful speed limit is less than 35 miles per hour, and for at least 200 feet before any proposed stop of such bus if the lawful speed limit is 35 miles per hour or more. For any new bus placed into service on or after July 1, 2007, such warning devices, at a minimum, shall include a nonsequential system of red traffic warning lights, a warning sign with flashing lights, and a crossing control arm such that when the bus door is opened, the red warning lights, warning sign with flashing lights, and crossing control arm are automatically activated. Failure of a warning device to function on any school bus shall not relieve any person operating a motor vehicle from his duty to stop as provided in §§ 46.2-844 and 46.2-859. Any person operating such bus who fails or refuses to equip such vehicle being driven by him with such equipment, or who fails to use such warning devices in the operation of such vehicle is guilty of a Class 3 misdemeanor. Transit buses used to transport school children in the City of Hampton may be equipped with an advisory sign that extends from the left side of the bus and displays the words: “CAUTION-STUDENTS.” Such sign may be equipped with not more than two warning lights of a type approved for use by the Superintendent of State Police.