Every motor truck having an unladen weight of 4,000 pounds or more, and every truck tractor irrespective of weight, when operated upon any street or highway during darkness shall be equipped with and carry at least two flares or two red lanterns or two warning lights or reflectors, which reflectors shall be of a type approved by the Department of California Highway Patrol. When any vehicle above-mentioned or any trailer or semitrailer is disabled upon streets or highways within this City and upon which street or highway there is insufficient street lighting to reveal a vehicle at a distance of 200 feet during darkness, a warning signal of the character indicated in this Section shall be immediately placed at a distance of approximately 100 feet in advance of, and 100 feet to the rear of, such disabled vehicle by the driver thereof. The continuous flashing of at least four approved Class A-Type I turn signal lamps, at least two toward the front and at least two toward the rear of the vehicle, shall be considered to meet the requirements of this Section until the devices mentioned above can be placed in the required locations. The warning signals herein mentioned shall be displayed continuously during darkness while such vehicle remains disabled upon such street or highway. Any trailer, semitrailer, dolly, fifth wheel or special mobile equipment not attached or connected to an operating tractor shall be considered a disabled vehicle for the purpose of this Section.