2001, Kathie Weir, A Parent's Guide to Los Angeles: Friendly Advice for Touring Los Angeles with Children[1], Mars Publishing, Inc., →ISBN, page 29:
The Lomita Railroad Museum was once a regular stop on our shopping trips, a little reward for my trainiac.
2006, James B. Twitchell, Where Men Hide, Columbia University Press, →ISBN, page 77:
There are still trainiacs, for sure — approximately 300,000 hardcore train hobbyists in the United States, who spend about $500 million on their passion.
2011 September 29, “The Pulled Groin Extrapolation” (00:10:27-00:10:32 from the start), in The Big Bang Theory, season 5, episode 3, Chuck Lorre, Eric Kaplan, and Jim Reynolds (actors):
Sheldon Cooper: It's official. I'm an HO trainiac.