I been driving for more than a decade. This question is always on my mind...
At junctions where there are left turn arrows, the left turn arrow will always coming up when the round lights are red. See below.
When the left turn arrow blinks and disappears, the round lights will carry on being red for 2 secs before turning green. Happens at all junctions.
Question is this. In that 2 secs, can I turn left?