high frequency intermittent noise

I live in a neighborhood where we have the oldest electrical system in the city.  A few years back, an underground power transformer blew up and caused quite a stir in the neighborhood - black smoke from the electrical fire coming out of a manhole from the street. 🔥 

Nothing gets replaced unless it fails, so it would seem for my neighborhood.  I don't think the electrical company would even give me any time considering the issues they are dealing with. 😊

I am afraid the US are sometimes a third world country, and this is one of those areas. Hope you can figure this one out. Can you find someone with a mobile phone to stand next to the subway line, or can you hear the trains when the windows are open, to confirm or refute your hypothesis?

If I listen carefully, I can hear the train go by underneath my building,  There is a low frequency buildup when this occurs looking at a real time analyzer, and I can actually hear the subway cars on the rails, so today I am listening carefully in between records to see if there is a correlation.

This issue is a low level issue, the noise I hear is just beneath the noise floor of the room.  So I'm chasing out the-last-bit of noise in my system. It's always that last 5% that is difficult. 🤓

Actually the new hot spot is Hudson Yards, that is where new construction is happening.  But I hear you, our infrastructure is falling apart.