A guide dog cannot read traffic lights or walk signs. Their blind or visually impaired handler must listen to the sounds of the traffic and decide when it is safe to cross. The dog serves as a safety net. If the handler makes a mistake or misjudges the traffic, the dog should refuse the command to move forward. However, once they are in the intersection, the dog should guide their handler safely to the opposite side. Cars turning a corner can be especially hazardous. There have been many instances when a guide dog has physically pulled their handler out of the street and out of harm's way.