You aren't the first person that has had that idea, tho. We even caught someone doing this quite a few years ago. We began to hear some strange conversations on the road channel (NS) as if someone who didn't know the radio phone procedures was trying to hail trains on the Charlotte (NC) District, but the train crews seemed to ignore them. i went to something called a "hamfest" (a gathering of Radio Amateurs) and a guy in a Southern RR hat noticed my SR "greenlighter" jacket.
He began to brag about how he could talk to the trains as if he had special privileges, yet he was simply an overwrought foamer. He was using his modified ham radio to talk to the trains and pointedly showed me he could do it. He was the guy we were hearing on the road channel at times! I didn't say a word back. I quietly went to a phone (before cellphones) and called the Railroad dicks! They were there in minutes. They siezed the handie talkie for evidence and, I assume, turned the matter over to FCC. We never heard anybody "bootlegging" anymore.
If you want to listen to the trains, get a scanner. Listening is perfectly fine in
most states. Look on the internet to find states who have prohibitions on scanners in cars or portables. Transmitting on the RR frequencies causes safety and interference issues.
Gadfly