In my area, many of the outdoor warning sirens are placed directly next to these small buildings. They all seem to be around the same size and have exhaust vents.
I would guess that they are tornado shelters. If your in a tornado prone area, it makes sense. That and it wouldn’t be the first time sirens were next to or near shelters as, from what I have seen, some of Hawaii’s air raid shelters have the Thunderbolts on site.
The generator thing would make sense. Do you think the generators could also be powering the sirens? Most of the sirens in my area have no battery backup.
Those are public works buildings, pump houses, FD or PD storage, etc.
They put sirens on already city-owned property so it can be easily maintained and doesn’t take up extra space.
Here are the siren models in order of photo: #1: Federal Signal 2001-130 #2: Federal Signal 2001-SRNB #3: Federal Signal XT22 (unsure if it is a 3T22 or 2T22) #4: Federal Signal 2001-SRNB(?)
I agree with @TS_Sirens-And-EAS
Probably public works buildings. Could be sewage/waste water, communications, or electricity. Pretty difficult to find out what’s inside without going inside.
The city probably puts their sirens at These city buildings because they are city property. I would highly doubt any sort of shelter would be in there. Near my house there’s a similar looking building and it’s used for the sewer/wastewater.