Mobile Sirens?

[MaineCivilDefense]

A while back I was looking at local Emergency Planning documents, and I found something intriguing I've never seen before. In areas that aren't served by A Fixed Siren, Emergency Vehicles would be driving with their sirens producing A Steady "Alert" tone.
I've never seen a vehicle siren with an Alert tone feature before, and after doing some research, I can't find any units with it. Has anyone else seen this?

I have scanned several pages that mention this from the Emergency Planning documents. If you would like to see them, i'll post them.

[Synther]

That signal can be achieved by holding down the manual button on almost any vehicular siren.

[MaineCivilDefense]

I know, but there was a dedicated button for it on the siren units themselves.

[Unit of Civil Defense]

I cannot provide any documented proof other than what I know to be factually true.....
I can give you 3 different instances that I am aware of where an alert (for a Tornado warning) was given, but not by means of a conventional outdoor warning device....a siren.

1) Although they are not mobile , the shift change steam whistles at a couple of local industrial plants back in the 60's would sound their whistles in the event of a Tornado warning.....both where located adjacent to neighborhoods.

2) In a story that I have read about the devastating Udall, Ks. Tornado which occurred aprox. 10:30 at night, an engineer of a train approaching Udall saw the monster Tornado in the flashes of lighting and "Laid into the trains horn to try and warn of the approaching Tornado"

3) I recall seeing television video of LEO's using wail in their patrol cars to warn a mobile home park of an approaching Tornado in either Butler or Sedgwick County Kansas back in the early 90's ...... I'm assuming that the wail sound of a police car siren most closely resembles a Tornado siren to some instead of wail/yelp, Hi-LO, yelp, air horn, etc etc. that you are more likely to hear when a unit is responding to an emergency call verses warming of an approaching Tornado. A Federal Q siren would be a good audio example of this.
Getting back to the video that I saw, there was at least one officer on his patrol car P.A more or less pleading with the residence of the park to find the mobile home park shelter or flee the path of the oncoming Tornado....and believe it or not there where some who did not heed the warnings and paid the ultimate price.

[SoundOff]

The Federal Signal PA-20 Interceptor had a version with an "Alert" signal in place of the Hi-Lo signal

[MaineCivilDefense]

After doing some research I had found that the GE Powercall siren had the Alert feature as well. Was the Alert signal dedicated for emergency alerting? Or was it used for other purposes?

[Unit of Civil Defense]

The ‘alert’ tone is just a steady tone that plays at a constant pitch......that's all.....I have heard it before...It doesn't sound like what you are hoping it sounds like rather just an early 60's electronic siren found in use in Police Cars , Ambulances, etc. It has absolutely nothing to do with Civil Defense or mimicking the sound produced by a Thunderbolt as an example. I'm sure that if you do some looking that you might stumble across an audio sample of either the Federal PA 15 or PA 20 alert tone.

Source: https://www.professionalcar.org/federalsirens-447

[SirensOfNewYork]

I'm sorry to bump but I do have something to contribute here. European companies like Telegrafia, Klaxon, and Kockum Sonics all manufacture mobile sirens that are not classic police sirens, but are full on, super loud sirens. These are meant to be driven through a city to warn a large area.