A. Whenever any commercial motor vehicle as defined in § 46.2-341.4 is stopped on any roadway or on the shoulder of any highway in the Commonwealth at any time for any cause other than stops necessary to comply with traffic control devices, lawfully installed signs, or signals of law-enforcement officers, the operator of such vehicle shall immediately activate the vehicular hazard warning signal flashers and as soon as possible, but in any event within 10 minutes of stopping, place or cause to be placed on the roadway or shoulder three red reflectorized triangular warning devices of a type approved by the Superintendent. One of the red reflectorized triangular warning devices shall be placed in the center of the lane of traffic or shoulder occupied by the stopped vehicle and not less than 100 feet therefrom in the direction of traffic approaching in that lane, a second not less than 100 feet from such vehicle in the opposite direction and a third at the traffic side of such vehicle not closer than 10 feet from its front or rear. However, if such vehicle is stopped within 500 feet of a curve or crest of a hill, or other obstruction to view, the red reflectorized triangular warning devices in that direction shall be so placed as to afford ample warning to other users of the highway, but in no case less than 500 feet from the stopped vehicle. Vehicular hazard warning signal flashers shall continue to flash until the operator has placed the three red reflectorized triangular warning devices required in this subsection. The placement of red reflectorized triangular warning devices is not required within the corporate limits of cities unless, during the time which lights are required to be illuminated on motor vehicles by § 46.2-1030, the street or highway lighting is insufficient to make such vehicle clearly discernable at a distance of 500 feet to a person on the highway. Flares or torches of a type approved by the Superintendent may be used in lieu of red reflectorized warning devices. In the event that the operator of the stopped vehicle elects to use flares or torches in lieu of red reflectorized triangular warning devices, the operator shall ensure that at least one flare or torch remains lighted at each of the prescribed locations as long as the vehicle is stopped. If gasoline or any other flammable liquid or combustible liquid or gas seeps or leaks from a fuel container or a commercial motor vehicle stopped upon a highway, no emergency warning signal producing a flame shall be lighted or placed except at such a distance from any such liquid or gas as will ensure the prevention of a fire or explosion. The exception provided in this subsection with respect to highways within the corporate limits of cities shall not apply to any portion of any interstate highway within the corporate limits of any city. The provisions of this section shall not apply to any vehicle in a work zone protected by flagmen or approved temporary traffic control channeling devices, as required by the Virginia Work Area Protection Manual or to any vehicle displaying a flashing amber light authorized by § 46.2-1025 when such vehicle is (i) used for the principal purpose of towing or servicing disabled vehicles, or (ii) engaged in road or utility construction or maintenance.