Well, here's some news about the Plainfield "diamond"!
I was talking to a friend who has worked for the P&W for 4 - 5 years, and asked him about Plainfield.
Turns out that the diamond has interlocking protection by confirmed dispatcher authorization.
The dispatcher determines the sequence of train movements, and no train enters the interlocking without obtaining confirmed clearance from the dispatcher!
"Jest cuz you don't see it, don't mean it's not there!"
--- a quote from one of my favorite movies!
So, next time you see a diamond without some form of physical hardware for interlocking, it doesn't mean that the diamond is not interlocked!
Sorry to rain on your parade!