Three-aspect traffic lights for vehicles

The image shows ordinary traffic lights for vehicles, with red, amber and green aspects. They normally control vehicles at junctions: red requires drivers to stop before the stop line; green permits them to proceed with due care; steady amber requires them to stop if this can be done safely, or to clear the junction if they have already entered it. Flashing amber allows traffic to proceed with particular caution and at a moderate speed. If the signals are switched off or out of order, drivers must proceed very carefully and comply with the applicable signs and priority rules. A red light does not permit a turn or crossing merely because the road appears clear.