As someone who lived in El Presidio Neighborhood for most of the ’90s, I got used to the blare of the train horns (and enjoyed them for the most part, except when they drowned out the dialogue in my pre-TiVo days). But it never occurred to me to find out exactly what the horns meant, other than "get the hell off the tracks."
But Mike Powell, who is more curious than I, did some investigation for Deadspin:
My wife and I recently moved to a house in the Dunbar/Spring neighborhood of Tucson, Ariz. Because we had never visited the house in the middle of the night, we didn't realize quite how loud the freight-train horns were. We have adjusted, in part with the help of earplugs. (To spoil another potential list, let me recommend Hearos Xtreme Protection, which at 33NRR not only offer the highest protection recognized by OSHA, but also come in a very handsome blue color.)
As a child, I loved the sound of trains. They seemed spectral and romantic. I also liked the reminder that work was still being done at a time when most people were sleeping. It connoted progress—like night was just preparation for day, and day for night. But like many things that were romantic to me as a child, the reality of the train horn has set in like a rude and bitter light.
My call to the media office of Union Pacific was met with friendly curiosity. I can't say I've ever gotten that question before, they basically said—the question being, "How can I find out exactly what train horns are blowing in my neighborhood?" (I regret not asking what kinds of questions they do get.) In any case, I have ventured to make of my circumstances what I can. With some relevant history and musicological dissection, here is a speculative list of my favorites.