Runs on a Siratone according to a 2011 streetview. Probably has been upgraded to a Ultravoice, but we cannot see as the road leading to this siren has been fenced off.
So, I got bored and decided to surf Google Patents, and stumbled upon a odd-looking Thunderbeam and 2001 expired siren patent. I'm guessing they are second generation designs or new designs. I haven't seen any photos or videos related to these sirens at all. After reading the description, it is said...