I'm guessing here that the statement was made in the context of driving. Apparently, something has been added to traffic intersections to make them safer. It could be some law, or more probably, they could be talking about some device. What it seems to be saying is that each time the add the device (or enforce this law) at a single traffic intersection, it becomes safer. It's a dramatic way of saying that they are improving traffic safety. [If this doesn't have anything to do with driving, I humbly apologize]

You really have to state the context when you ask these questions. I, too, am guessing the context is driving. Look up the word "intersection" and I'm sure you'll understand this sentence.