When is it time for a senior citizen to quit driving?

Ruth realized that she had better turn in the keys when her and Martha were riding down the road and chatting. As they were riding they were approaching a red light. Martha realized that her sister Ruth didn’t slow down but ran right through the red light. Martha said, “Wooh, that was a close one!” They approached a second red light and went through that one full speed. Martha gripped the seat of her chair as they went through a 3rd red light. Martha yelled out, “Stop Ruth you just ran through 3 red lights!” Ruth looked at her with a confused look and said, “Oh I thought you were driving!”