Traffic Signals, Controller Signals and Priority of Signals
Signal meanings
A round green light means go if the way is clear; a green arrow means go in the indicated direction. A flashing green light warns that the phase is ending. A yellow light means stop unless stopping would be unsafe; a flashing yellow means proceed with caution. A red light means stop. A red light with a green arrow allows movement in the arrow direction after yielding to other traffic. A tram has priority when its signal and the vehicle signal both allow movement, unless a sign says otherwise.
Controller signals
A traffic controller's signals override all lights and signs. Arm raised vertically: all traffic must stop. Arm extended forward or to the side: traffic may proceed from the controller's side, but must stop from the chest and back. The controller's baton or hand position tells you which direction is open, so read the body orientation, not just the arm.
Traps in questions
A classic trap is the yellow light: the correct answer is 'stop, unless you cannot stop safely', not 'speed up'. Another is the red light with a green arrow: you may turn, but you must yield to traffic already in the intersection. Questions also test the flashing yellow, which never grants priority. Finally, remember that a green light does not guarantee a clear path - you must still yield to pedestrians and to vehicles finishing their manoeuvre.
Rule of thumb
Order of authority: controller, then traffic light, then sign, then marking. When in doubt, yield.
Worked example
A driver faces a red light with a green left arrow. The correct action is to turn left after giving way to oncoming traffic and pedestrians, not to wait for the full green.