1. It indicates that the flashing yellow light is about to appear. You should drive faster and clear the intersection immediately.
  2. It indicates that the flashing green light is about to appear. You should drive faster and clear the intersection immediately.
  3. It indicates that the red light is about to appear. You should prepare to stop or clear the intersection immediately.
  4. It indicates that the stable (not flashing) green light is about to appear and you would be able to continue driving.