Ask Haighteration: What's With the Mysterious Train Whistle?

Last week, a Haighteration reader emailed us the following:

I've lived in the neighborhood for a few years and I swear, every once in a while I hear a pretty loud train whistle. I heard it again tonight around 10pm. As far as I know there aren't any train tracks anywhere around here!! Do you know what that sound is, or am I going crazy?????

No, reader, you're not going crazy.

We've heard that whistle too. And we've been similarly perplexed.

A little googling turned up a couple of threads on Yelp, with folks speculating that it's everything from foghorns, to a ghost diesel locomotive in the Sunset, to a modified car horn, to echoes of Caltrain, to a siren letting folks know Golden Gate Park is closed — but no definitive conclusion seems to have been reached.

So, readers, we'll leave it to you. Have you heard the train whistle? If so, do you know what it is? Let's get to the bottom of this, once and for all!