About a month ago I noticed Con Edison workers building a giant wooden box in the middle of the street in my neighborhood. It was long enough to park maybe 2 cars in.

The box on 47th Avenue.

The work to bury and activate the box (sorry for the trees, most of the juicy visual is behind them).
Naturally I was curious so I asked one of the guys working the site what it was. He explained that it was an "underground monitoring facility". I guess the idea was to build this giant box, populate it with all the ports needed for wiring and plumbing, then drop it in the ground and cover it all up. Workers would somehow get into it from above ground when they needed to, perhaps via manhole. It all struck me as kind of a neat thing and a neat way to do the job.
Oddly, though, the box suddenly disappeared one day. It was as if they just carted it off rather than drop it in the ground after all. It looked almost done and quite habitable, so I was surprised. I was under the impression they were building the box on the very spot they intended to bury it, but alas, I was obviously mistaken. Or so I thought.
Yesterday on the way into my building, I noticed the box was back. Right there in the middle of the street again along with orange pylons and flag wavers all doing their best to direct traffic around it. This time there seemed to be a lot more workers and a lot more urgency in the ongoing activity. The workers continued working through the night, lighting the entire block with high beams that turned night into day. My feeling is they are now putting the final touches on the box and preparing to lower it into the ground.
So just what is this "underground monitoring facility" for exactly? A few seconds at Google and some choice query words quickly revealed this project. Kewl. Apparently I'm dead smack in the center of the Sunnyside component to this experiment.