I think the underlying problem is that Collingwood north of GR is coming in at an angle, and for left turning vehicles coming from the south (not the South) it is difficult to recognize. In addition, there are two lanes going straight. Since the intersection is very busy and it is difficult enough for drivers to figure out even where the lanes are, I am very doubtful that an additional sign would help any. I once had a car turn left in front of me going into the wrong separated lane on GR. That's how confused some drivers are at this intersection.