Crossing communicating.(Chicago Perspective)

Over the years, I've been drawn into many discussions about grade crossings and grade-crossing safety. But how much do we really know about them? How did they come to be? Who is responsible for deciding where different types of grade-crossing warning systems are to be installed? Who decides when a grade separation will be put in place?

I thought I knew the answers to these questions, but I wasn't exactly right. And if some one like me, who has spent decades in the railroad industry, doesn't know, how can we expect the average journalist or just plain motorist to know?