This is a traffic signal on the Jeffrey off-ramp from the northbound 5 in Irvine. The ramp is 3 lanes wide, and the middle lane can go either way. It’s not often that you actually see a double arrow like this, though.
It’s times like this that make me wish I’d taken a picture of the “U-Turn Only” sign I saw a few years ago. The street it was on has since been extended, and the sign is long gone.
