Specifically, this is about driving your car or truck when making left turns at an intersection with a traffic light.
Of course, you don't want to make a left turn until incoming traffic comes to a full stop. Of course.
Often, in the past, this was when your light goes from green to yellow. Then you turn.
That no longer works, however.
Now, you have to wait until all the incoming traffic completes running the red light. This may take several vehicles.
After all the incoming traffic runs the red light, now it will be safe for you to complete the left turn.
I hope this helps. Drive safe!
