Let's say you're driving around town and you come to a traffic light that should be directing traffic, but all the lights are off, just like the intersection of 4th Avenue and Main Street in Royersford on Friday morning? If that happens, how are you supposed to drive through that intersection?

According to chapter 2 of the Pennsylvania Driver's Manual:

"A non-functioning traffic signal should be treated as though it were a four-way STOP sign."

So, if you come to a broken traffic light - pay attention and drive carefully!