The red car will drive through the intersection:

Explanation

First.

The traffic light is green and the green car in the foreground has switched on its left indicator; that is, it wants to turn left at the junction. The rule is clear: a driver turning left on a green light is obliged to give priority to vehicles coming from the opposite direction going straight or turning right. The red car comes from exactly the opposite direction, so it is the one that passes through the junction first, and the green car must wait inside the junction.

The yellow diamond "priority road" and the direction plate beneath it, posted on the right of the picture, are the trap of this very question. When a junction is controlled by a traffic light, priority signs do not determine the order of passage; those signs mean something only when the light is switched off or in flashing amber. Nor does a green light mean "the way is clear"; it merely permits entry into the junction.

The safety reason for this rule is the geometry of the left turn: a car turning left cuts across the full width of the opposing path, and at that very moment the bodies of the oncoming cars and the junction's pillars block its view. A left-turn crash with an oncoming car is one of the most frequent and most lethal urban collisions, because the impact occurs head-on at a high relative speed.

• This option looks right if you take the priority-road sign beside the light as a mark of the green car's advantage, or think the red car must wait for the left turn to be completed; but on a green light it is the turning car that gives priority to oncoming traffic.

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