Anyone know what this is?

Because it is train related, this came from my dad. He built his collection that ranged from H/O scale trains, small sections of track, other random things and now apparently a key.
That's exactly why I have mine. when I moved here, I became obsessed with anything American with wheels and I got into the model railroading scene even though I was really out of my normal realm. It was all old guys and me at the model railroad events. LoL

I met an older gentleman who kinda became my mentor and he worked for the union pacific at the time. He gave me that key and said two things about it: 1. Never attempt to use it (good way to go to jail) 2. Never tell anyone where I got it from lol. He has since passed away but I'm still not talking lol.

Its sentimental to me now because what it is and who gave it to me. I have since given up on model railroading because the mopars are an all consuming hobby that leaves no room or money for other hobbies. I still like to go train watching on cold winter days when no one else is around and the noises from the locomotives really resonate as the gentle clouds of steam surround them from the heat of operation.

It's really something and the history of the American rail industry is like no other in the world.