I've been up there many times, for various reasons (railfan related), and can't see how in the world you could get hit by a train. Those diesels are so loud, you'd have to be deaf to get hit.
If you stay away from the tracks, the CSX crews don't mind you being there. They've always given me warm waves.
I have noticed that security has tightened around there. I decided to roam around on a Sunday when there's no activity, and saw a CSA security guy hop in his SUV in hot pursuit (of me?). I was gone before he reached my area, but I suspect they're trying to crack down on the large number of kids on ATV's who think the ex-Reading yard is their playground.
Incidently, anyone who wants to railfan there, Monday is a great day. There are always freight moves in the evening. The NS concrete train comes through a few times a month too, and you can get great shots of it over on Allegheny, on public property.