I've decided to start documenting the history and evolution of ACA and ASC siren controllers, in order to hopefully clear up confusion and present this information in an easily digestible format. Feel free to contribute any information or corrections if my information is incorrect. First up, the AS...

I hope someone captures this event on camera, so those of us who live too far away (like me, down in Georgia) will have a chance to experience it.

https://www.google.com/maps/@41.876102,-87.7146275,54633m/data=!3m1!1e3!4m2!6m1!1s1cncIMTft_wigSetoMlblNct74BXKTn4 I have created a map to keep track of these replacements because I am now sure there are more. If anyone notices any new ones, please let me know! I know it's off-topic but how did you...

Oops! Forgot to make the map public. Here is the new link: https://www.google.com/maps/@41.8689162,-87.8082858,36900m/data=!3m1!1e3!4m2!6m1!1s1cncIMTft_wigSetoMlblNct74BXKTn4 Here's the link if you open with Google My Maps. https://www.google.com/maps/d/u/0/viewer?hl=en&mid=1cncIMTft_wigSetoMlb...

Wow!! If you go into the alley, you can see the new pole installed next to the old siren in the August 2022 street view. Looks like Chicago is replacing quite a few sirens. Looks like my initial speculation might come true, at least partially in some form. ↓ ↓ ↓ ↓ ↓ ↓ Yeah, Chicago's system is from...

Well, at least they're upgrading/replacing them with good sirens and not doing away with sirens altogether.

4. A 2001-DC on an obscenely thick pole. There's a few others like this scattered around. https://www.google.com/maps/@44.832105,-93.3934399,3a,15.4y,71.74h,96.91t/data=!3m7!1e1!3m5!1sDTpMF4PlLL5EiSxCMbU22A!2e0!6shttps:%2F%2Fstreetviewpixels-pa.googleapis.com%2Fv1%2Fthumbnail%3Fpanoid%3DDTpMF4PlLL5...

The ASC T-128 that replaced the Sentry Defender in Argos, Indiana has a different horn design that appears to use less fiberglass. ------------------------------------------------------------------------------------------- T-128 new horn.png ----------------------------------------------------------...

Here's this ASC T-128 located next to the outdoor track at Plainview High School in Ardmore, Oklahoma:

It's hard to tell from this image, but that looks like it is one solid object. It might possibly be a distribution transformer of some sort, as it's on a pole with power lines running nearby.

It does have the Thunderbeam shape to it, though.