Gravesend Street Sign is Confusing

This warning sign on Ave R and East 8 St in Gravesend appears to be quite official, but does not indicate any city agency in charge. If it’s a local homeowners association that placed it, there’s no identification as such.

I have a few questions about this bold, but ambiguous, sign and would appreciate any answers local residents may have.

What is the sprinkler system that the sign is referring to and how does it get activated? Why would the sign identify this small grass-covered median as a boulevard? Has there been some problem with people rushing to the median during emergencies?

It seems to me, that if there was a raging fire in the buildings nearby or other dangerous situation on the sidewalk, I might want to rush to the median. If you look just past the sign, you can see the brick footpath, but pedestrians are warned to keep off of the boulevard. How are they supposed to get to the other side of the road?