Actually when I rode the Amtrak Pacific Surfliner from Santa Barabra to San Diego, CA I paled around with the conductor and on the little radio thing he always said something like:
"Looks like we got everyone on. Highball Amtrak 7-7-4!" and then you hear to blasts of the horn in acknowledgement and ur off.
I believe riding the Regional I have heard it a few times too.
Davis