On the first Tuesday of every month, 112 sirens
are switched on around the city of Chicago.
They are part of the our Emergency Warning
System, designed to warn people of immanent
danger. Today, that mainly consist of natural
disasters, however, the reason they were installed
in the first place is far more ominous
When America was thrust into WW2 with the
bombing of Pearl Harbor the office of civilian
defense was formed to prepare the country
for other possible attacks. The main threat
would be an air attack, so major air raid
siren networks were installed throughout the
country. Chicago started by installing 5 sirens,
two of which were Chrysler Bell Sirens. Weighing
in at 5 and half thousand pound, the Chrysler
Air Raid Siren is the loudest sound signaling
device ever built. It produced 138 dBC at
100 feet away. The sound of a commercial airplane
taking off at the same distance is about 110
dBC. The siren would spin on its axis providing
a two and one-half mile radius coverage area.
1000’s of people gathered in the loop for
what would be the first public testing of
the system in April 1942. However, they were
would be disappointed as all they could hear
would be distant wail. To fix the problem
and create an effective system Chicago would
install 20 Chrysler Air Raid Siren and additional
smaller steam sirens. Soon we would amass
a system of nearly 100 sirens strategically
located around the City of Chicago
During the war, the system was only tested
sporadically, mainly for the purpose of training
operations. Given the time the siren system
couldn’t be beaten as you had the ability
to warn the whole city almost instantly of
imminent danger.
The sirens would give off a 2 minute fluctuating
sound to alert for imminent danger, civilians
would then find refuge they could then tune
into the radio for further updates or wait
for the sirens gave a 2 min continuos pitch
sound to announce the all clear.
As would be expected, the sound of any siren
could create panic, so during the war Chicago’s
emergency vehicles were banned from using
their sirens, they had to rely on bells, whistles
and rattles instead. After the war Chicago
kept its system around as new treats were
brewing from the cold war and the possibility
of an atomic attack.
In 1952 Chicago’s civil defense testing
the system weekly, 10:30am every Tuesday.
It was time of great tension and children
were learning the whole “duck and cover”
in School. In 1959 after the White Sox won
the american pennant the Fire commissioner
Robert Quinn ordered a celebratory five-minute
sounding of the air-raid sirens. People were
not very happy as it caused quite the panic.
With the treat of the cold war fading away
Chicago continued the weekly test of its system.
All the way up until 1989 as far as I’m
aware. Even though at that time the system
was in disrepair with only 17 of the sirens
actually working. While most major cities
decided to decommission their systems, Chicago
elected to revamp it and in the late 90’s
installed a new 2.2 million dollar system.
Today the system will sound for 3 minutes
at variable pitch to signify a major emergency
or disaster, this includes severe storms,
tornado warnings, earthquakes, chemical hazard
or hazardous material incident, extreme winds
and biological hazards or event. While some
sirens have the tradition air raid sound,
other use a variable pitch. The combination
of these along which the weather can create
quite the spooky other worldly experience.
Today we have the ability to send alerts to
mobile devices and with technology even more
accessible than before people are starting
to question the effectiveness of the siren
system. However, the main reason for keeping
it around is to alert those who are outdoors
and for those who are not exactly technologically
able. So for the time being the monthly tests
will continue and Chicagoans will go on without
even noticing.
If you want to learn more about the technical
specification of the siren you can do so by
watching the video here. I wanted to thank
Alex The Chicagoan for suggesting this video,
if you want to suggest your own you can do
so in the comments or in link in the description.
