Driving home from work there was a broken down car half parked on the verge with the driver attempting to direct traffic. Completely pointless as there was plenty of room for vehicles to pass in both directions. The driver was getting quite annoyed that he was being virtually ignored, but what if there was a collision after someone did ignore him?
I know builders stop traffic to let lorries out but to my knowledge the public and even banksmen have no authority to stop traffic.