augmented train whistle

I just heard, for the first time in my life, a train whistle that was actually an augmented chord. Culturally, the augmented chord is the audio symbol of the train whistle: in music and movies that's how it's portrayed. But in real life, most train whistles are something else, usually major chords in various states of nearly-in-tune. And of course there's the Doppler effect, which swerves the sound of a moving thing, to help destabilize the sound. But I've never ever heard a real train that made a real augmented chord. Until just now.