It seems that traffic flow problems are becoming more and more common these days. In fact, despite the most noble efforts of city planners, even when there is very little traffic on the road, waiting seems to be a fact of life. So what is the probability that you will have to wait at a particular traffic signal, or perhaps more appropriately, what is the average amount of time you can plan on waiting? Let's look at a simple probability analysis related to traffic lights to find out.