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 three pot torches or three red electric lanterns or three red emergency reflectors, which reflectors shall be of a type approved by the California Highway Patrol. When any vehicle above mentioned or any trailer or semi-trailer 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 above shall be immediately placed as follows: one at the traffic site of the disabled vehicle not more than 10 feet to the front or rear thereof, one at a distance of approximately 100 feet to the rear of the disabled vehicle in the center of the traffic lane occupied by said vehicle, and one at a distance of approximately 100 feet to the front of the disabled vehicle in the center of the traffic lane occupied by such 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.