You approach an intersection where the traffic light is green, but a police officer standing in the middle of the junction is signalling you to stop. What must you do?

Why B is correct

When a traffic officer is directing traffic, the officer's instructions replace the signals and signs for everyone at that junction. The reason is practical: an officer is standing in the middle of a situation that the fixed signals cannot see, such as a crash, a signal malfunction, a parade or a flooded lane, and the officer can read the whole scene while you can read only your own approach. Disobeying the human controller because a light is green puts you into whatever the light cannot see, which is usually the very hazard the officer is managing.

Why the other options are wrong

A. Follow the green light, because signals always take precedence over gestures

Signals run on timers and detectors; they have no knowledge of what is happening in the junction at this minute. A green light that conflicts with an officer's direction is a light that does not know about the crash, the flooded lane or the fallen wires the officer is standing in front of.

C. Stop, then proceed on the green regardless of further gestures

Stopping and then proceeding on green anyway defeats the entire purpose of manual control. The officer's direction is not a pause before the signal resumes authority; it is the authority for as long as the officer is directing.

D. Sound your horn and wait for the officer to wave you through

Honking at the person controlling the junction adds noise to a scene that is already abnormal, and it misreads the situation as a negotiation. The officer is not going to change the direction because a driver requests it; the direction reflects the state of the whole intersection.

On the road

A signal has failed after a storm at a four-way junction near your office, and an officer is waving batches of cars through from alternating directions. Your approach shows green, which means nothing now. The officer's palm faces you: you stop, wait through two full waves of cross traffic, and move only when the wave includes you. It costs ninety seconds and the junction keeps flowing.

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