Civil defense siren

 ( Civil Defense ) 

Switzerland currently has 8,500 mobile and stationary civil defense sirens, which can alert 99% of the population. Federal Office for Civil Protection (FOCP) – Visited on Wednesday, 10 February 2010 There are also 700 sirens located near dams. Every year on the first Wednesday of February, Switzerland's sirens are tested to see if they are functioning properly. During this test, general alert sirens as well as sirens near dams are checked. The population is informed of the test in the days leading up to the tests by radio, television, teletext, and newspapers, and the siren tests do not require the population to take any special measures.

The tones of the different sirens are provided on the last page of all phone books as well as on the Internet.

• General alert: a one-minute regularly ascending and descending tone, followed by a two-minute interval of silence before repeating. The 'general alert' siren goes off when there is a possible threat to the population. The population is instructed to inform those around them to proceed inside. Once inside, people are instructed to listen to emergency broadcasts made by the broadcasting networks SRF, RTS, RSI and RSR.
• Flood alert: 12 continuous low-pitched tones, each lasting 20 seconds. The flood alert is activated once the general siren is sounding. If heard by the population in danger zones (such as near dams), they must leave the dangerous area immediately or find shelter.

The observed use of sirens in Ukraine has been the following:

• Danger threat: Repeated long bursts
• All Clear: Final Short burstAudio from Ukraine Live feed sources

Air Alert is an air raid warning app developed by Ukrainian company Ajax Systems and web development company Stfalcon. In early 2022, at the beginning of the Russian-Ukrainian war, the app was quickly launched and integrated government data to provide real-time air raid alerts. As of July 2023, the app has been downloaded more than 15 million times. According to research, the app can reduce civilian casualties by 35%-45%.

Since the Russian invasion of Ukraine in 2022, air raid sirens have sounded more than 40,000 times, and these alert citizens to seek shelter. However, the frequency is so high that many residents no longer choose asylum. This usually depends on the time, place and personal situation, and some people give up because it is too late to seek asylum. The continued attacks pose a serious threat to the physical and psychological health of the residents.

• Red warning: attack in progress or imminent (attack/wail)
• All clear: attack over (steady alert)

These tones would be initiated by the Royal Observer Corps after spotting Luftwaffe aircraft coming toward Britain, with the help of coastal radar stations. The red warning would be sounded when the Royal Observer Corps spotted enemy aircraft in the immediate area. The sirens were tested periodically by emitting the tones in reverse order, with the all clear tone followed by the red warning tone. This ensured the public would not confuse a test with a real warning.

Every village, town, and city in the United Kingdom used to have a network of dual-tone sirens to warn of incoming air raids during World WarII. The operation of the sirens was coordinated by a wire broadcast system via police stations. In towns and cities with a population of over 3,000, powered sirens were used, whereas in rural areas hand-operated sirens were used (which were later put to use as warnings for nuclear attack during the Cold War). At the end of the Cold War in 1992, the siren network was decommissioned, and very few remain. These sirens, mostly built by Carter, Gents, Castle Castings, and Secomak (now Klaxon Signal Co.), have 10 and 12 ports to create a Minor third (B and D notes) and are probably the world's most recognised World WarII air raid siren sound. Recordings of British sirens are often dubbed into movies set in countries which never used this type of siren.

Around 1,200 sirens remain, mostly used to warn the public of severe flooding. They are also used for public warning near gas or nuclear power plants, nuclear submarine bases, Oil refinery and . The remaining sirens are a mix of older motor driven models (usually from World WarII), such as the Carter siren manufactured by Carter's of Nelson or the "syren" manufactured by Gent's of Leicester, and Cold War like Castle Castings and Secomak (now Klaxon Signal Co.) and newer electronic sirens like Hormann ECN, Whelen, Federal Signal Modulator, ATI HPSS and COOPER WAVES. Most of them usually tested annually between August and September if they're not in a siren system. They are also used to start and finish silences on /ref>

There was a siren system consisted mainly of Castle Castings and two Secomak GP3s for their flood warning system sector. When MoD was decommissioning these systems across the country, Norfolk kept their sector back for flood warning. With the advent of digital services and mobile technology, many local authorities are now retiring their siren networks in favour of contacting people by telephone. In January 2007, proposals to retire a network of sirens in Norfolk were made by the Norfolk Resilience Forum. In November 2007, residents were angered after the sirens had not sounded following a Storm surge in Walcott. In 2008, a review of the current and future role of flood warning sirens was undertaken by Norfolk County Council, after plans to retire them were halted following concerns from nearby residents. Although some of the sirens were initially withdrawn, 40 out of the 57 were eventually temporarily reinstated. Despite this, in July 2010 the flood warning sirens were finally retired in favour of alerting people by telephone, SMS or Email. After three years of consultations, the council had failed to demonstrate that refurbishing the sirens would be a worthwhile investment. The whole siren system was completely gone by late 2013, with only two sirens remaining, which are both inactive with one of them refurbished and put on display on a beach not far from its original location, and another, in Mundesley Fire Station, just standing there, extremely unlikely to ever sound again.

Lincolnshire, which had one of the largest siren systems in the country consisting of Carters, had 46 sirens based in North Somercotes, Mablethorpe, Boston, Skegness, Spalding and Sutton Bridge, as well as inland at Louth, Horncastle, Middle Rasen and Gainsborough, the areas most at risk of being hit by floods. Following serious flooding in the summer of 2007, investigations took place into how the flood warning system could be improved. The Environment Agency admitted that the warning system in Louth had not sounded early enough. In April 2008, Lincolnshire County Council began to investigate the possibility of replacing the flood warning sirens with mobile phone alerts. A council report in November 2009 described the sirens as being "outdated, in the wrong places and difficult to repair". The sirens were eventually decommissioned in November 2011 and replaced with Floodline.

In January 2010, 13 public warning sirens on the island of Guernsey that had first been installed in 1937 were due to be retired and replaced by text messages. This followed claims by the Home Office that the sirens had "reached the end of their useful working life". The sirens had previously been used to warn of major incidents. From 1950 to 2010, the Civil Defence Committee took responsibility for the sirens, and had tested them annually since 9 May 1979. Members of the public had criticised the decision, and Deputy Janine Le Sauvage claimed that sirens were the only way everyone knew there was an emergency. In February 2010, 40 islanders formed a protest march opposing the proposal to retire the sirens. The campaigners accused the government of not listening to them, as an online petition calling for the sirens to be saved was signed by more than 2,000 people. In April 2010, it was decided to dismantle the public warning system. Emergency planners had proposed to use a new warning system that would contact residents by telephone; however, this was abandoned due to technical limitations and local media and other communication methods are used instead. Only two remain in Guernsey, one in Victoria Tower, which sounded off once at around 2017, and another, active for a quarry.

Following severe flooding in Upper Calder Valley in June 2000, the Environment Agency replaced its network of sirens, with eight being placed around Walsden, Todmorden, Hebden Bridge and Mytholmroyd. The network was designed to complement the agency's Floodline service. These sirens became what is now known as the Todmorden Flood Warning System. There are nine sirens that are part of the system, five of them being Secomak, three of them being Klaxon and one of them being Carter (which was recently confirmed to be inactive according to the local environment agency).

In November 2010, 36 flood warning sirens in Essex, including nine on Canvey Island, were retired following concerns from the county council that the system was "no longer fit for purpose". The sirens were due to become obsolete in 2014. Only five sirens from the entire system remain, two of them in Canvey Island.

In September 2012, new flood warning sirens were installed in the Dunhills Estate in Leeds, as part of flood defence work at Wykebeck. In January 2014, flood sirens sounded for the first time in 30 years on the Isle of Portland.

Broadmoor Hospital used Broadmoor Sirens installed in 1952, which were tested weekly. These were consisted of Secomak CS8s, which were similar to a Secomak GP8 except the CS8 had coded shutters which could do an alternating hi-lo signal, and if designed to do so, could also do a pulse signal. For emergencies, they sounded the hi-lo and for all clear, they sounded a steady tone. In tests, they would sound the all-clear. In July 2014, plans were put forward to retire seven of the thirteen alarms, which had last been properly activated in 1993. The alarms are located in areas such as Sandhurst, Wokingham, Bracknell, Camberley and Bagshot. In June 2016, the West London Mental Health Trust, who manages the hospital, proposed decommissioning the sirens altogether and replacing them with social media alerts through websites such as Twitter. In December 2019, this entire system was decommissioned, in favour of a new Electronic siren located at the hospital. This siren is tested silently; however, on occasion (with prior notice from the hospital) it is audibly tested, but not at full volume.

A similar siren system in Carstairs, Scotland, called the Carstairs Hospital Siren System, uses nine sirens, seven of them being Secomak CS8, one being a Klaxon GP8 and one being Secomak GP12. The hi-lo signal is rarely used since during emergencies they sound a continuous tone for eight minutes, and in all clear they sound a long wail, consisting of thirty seconds of startup and alert and a thirty-second wind-down, three times. The test schedule is the third Thursday of every month at 1PM with the all clear.

There are several sirens in use around Avonmouth near Bristol to warn of chemical incidents from industry in the area. These are known as the Severnside Sirens. These sirens consist of Federal Signal Modulators and two DSAs, which were installed in 1997 for the public. The system is tested every third day of every month at 3PM. This consists of rising tones and a steady pulsing tone, followed by a steady tone for all clear. In emergencies, they will run for as long as the batteries can allow since they are off-grid powered.

• Dundas Street West and Shaw Street
• York Quay, Harbourfront

Sirens have recently been built within three kilometers (two miles) of the Darlington and Pickering Nuclear power in the province of Ontario. (Both plants are within 30 kilometers; 20 miles of each other.) These sirens will sound in the event of a nuclear emergency that could result in a release of radioactivity. Sirens have also been placed (and are tested weekly) in Sarnia, Ontario due to the large number of chemical plants in the vicinity. These consist mainly of ATI HPSS sirens, as well as a Federal Signal Modulator in the rail yards and three Thunderbolt 1003s located at the Suncor plant. Sirens have also been installed in and around the Grey Bruce Nuclear Generating Station. The sirens are on the plant and in the surrounding communities such as Tiverton, Ontario. One notable siren is a Federal Signal Modulator at the Bruce Nuclear Visitor's Centre. The Public Siren network as it is called, consists of mostly Whelens, Modulators, and Model 2s. One of the sirens in this network (a Model 2) is at Tiverton, which is about 10 km (6 miles) from the plant.

Many warning sirens in Ontario, Manitoba, Saskatchewan and Alberta are now used as tornado warning instruments. Smithers, British Columbia uses an old air raid siren as a noon-day whistle. New Waterford, Nova Scotia uses a siren to signal the daily curfew. One of the warning sirens was even used as a goal horn for the Quebec Nordiques between the mid-1980s and 1991. Caledonia, Ontario routinely uses an air raid siren to call in their local volunteer firefighters to the fire hall. NOAA Weather Radios in Canada are often used for advance warnings about future severe storms whenever people are at home, at a business or in a car.

Beginning in 1952, the Bell and Lights Air Raid Warning System, developed by AT&T, was made available to provide automated transmission of an expanded set of alert signals:

• Red alert: Attack imminent
• Yellow alert: Attack likely
• White alert: All clear
• Blue alert: High–low (Different warning, such as a local warning)

The yellow alert and red alert signals correspond to the earlier alert signal and attack signal, respectively, and the early Federal Signal AR timer siren control units featured the take cover button labeled with a red background and the alert button labeled with a yellow background. Later AF timers changed the color-coding, coloring the alert button blue, the take cover button yellow, and the fire button red (used to call out volunteer firefighters), thus confusing the color-coding of the alerts. In 1955, the Federal Civil Defense Administration again revised the warning signals, altering them to deal with concern over nuclear fallout. The new set of signals were the alert signal (unchanged) and the take cover signal (previously the attack signal). The all clear signal was removed because leaving a shelter while fallout was present would prove hazardous.

Sirens began to replace bells for municipal warning in the early 1900s, but became commonplace following America's entry into World WarII. Most siren models of this time were single-tone models which often sounded almost an octave higher in pitch than their European counterparts. Dual-tone sirens became more common in the 1950s, but had been used in some areas since about 1915. During the Cold War, standard signals were used throughout the country for civil defense purposes, referred to as alert and attack. Volunteer fire departments generally used a different siren signal. Many towns, especially in California and New England, used coded air horns or for fire calls and reserved sirens for civil defense use.

Today, signals are determined by state and local authorities, and can vary from one region to another. The most common tones produced by sirens in the United States are alert (steady) and attack (wail). Other tones include Westminster Chimes (commonly used for the testing of electronic sirens), hi-lo (high-low), whoop, pulse (pulsing), air horn, and fast wail.

The U.S. federal standard regarding emergency warning signals is defined in FEMA Outdoor Warning Systems Guide, CPG 1–17, published on March 1, 1980, which describes the Civil Defense Warning System (CDWS) and its warning signals. The language was slightly revised by FEMA's National Warning System Operations Manual, Manual 1550.2 published 03-30-2001:

• Attack warning: a three-to-five-minute wavering tone on sirens or a series of short blasts on horns or other devices. The attack warning signal means an actual attack or accidental missile launch was detected, and people should take protective action immediately. The signal will be repeated as often as deemed necessary by local government authorities to get the required response from the population, including taking protective action from the arrival of fallout. This signal will have no other meaning and will be used for no other purpose. (However, sometimes the attack signals are used for tornado warnings.)
• Attention or alert warning: a three-to-five-minute steady signal from sirens, horns, or other devices. Local government officials may authorize use of this signal to alert the public of peacetime emergencies, normally tornadoes, flash floods, and tsunamis. With the exception of any other meaning or requirement for action as determined by local governments, the attention or alert signal will indicate that all persons in the United States should "turn on their radio or television and listen for essential emergency information".
• A third distinctive signal may be used for other purposes, such as a local fire signal.
• All clear: no all clear signal is defined by either document.

The most common tone, alert, is widely used by municipalities to warn citizens of impending severe weather, particularly which have earmarked the sirens as tornado sirens. This practice is nearly universal in the Midwest and parts of the Deep South, where intense and fast-moving thunderstorms that can produce tornadoes occur frequently. The alert sound is a steady, continuous note. In seaside towns, alert may also be used to warn of a tsunami. Sirens that rotate will have a rising-and-falling tone as the direction of the horn changes. The attack tone is the rising and falling sound of an air raid or nuclear attack, frequently heard in war movies. It was once reserved for imminent enemy attack, but is today sometimes used to warn of severe weather, tsunamis, or even fire calls, depending on local ordinance. Criteria to sound sirens during severe weather events are established by regional National Weather Service offices and do not have an all clear signal.

There is no standard fire signal in the United States, and while the use of sirens by volunteer fire departments is still common, it is diminishing. In the dry areas of the American West, residents may be required to shut off outdoor water systems to ensure adequate pressure at fire hydrants upon hearing the signal. The fire signal can vary from one community to another. Three long blasts on a siren is one common signal, similar to the signal used by volunteer brigades in Germany and other countries, while other locales use the hi-lo (high-low) signal described above. Some communities, particularly in New England and northern California, make use of coded blasts over a diaphone or air horn for fire signals, reserving the use of sirens for more serious situations. Still others use the attack tone as their fire call. Some communities make use of an all clear signal, or sound separate signals for fire calls and ambulance runs. Some fire signals in the U.S. are often blasted at least once a day, mostly at noon, to test the system, and are often referred to as noon sirens or noon whistles. These also function as a time tick for setting clocks.

CPG 1-17 recommends that a monthly test be conducted, consisting of the steady attention signal for no more than one minute, one minute of silence, and the attack signal for no more than one minute. A growl test signal is also described by CPG 1–17, when a siren must be tested more than once a month. This is typically a one-second burst of sound to verify the proper operation of the siren without causing a significant number of people to interpret the test as an actual alert. Many cities in the U.S. periodically sound their sirens as a test, either weekly, monthly, or yearly, at a day and hour set by each individual city.

In the United States, there is no national level alert system. Normally, sirens are controlled on a county or local level, but some are controlled on a state level, such as in Hawaii. Sirens are usually used to warn of impending natural disaster; while they are also used to warn of threats of military attacks, these rarely occur in the United States. Throughout the Great Plains, Midwest, and South, they are typically used to warn the public to take cover when a tornado warning is issued, sometimes even for severe thunderstorm warnings, and very rarely used for anything else. They are generally required in areas within a ten-mile radius of nuclear power plants. In the South and on the East Coast (except for Texas, Maine, Florida and New Hampshire), sirens are used to inform people about approaching Tropical cyclone.

In Pierce County, Washington there is a system of sirens set up along the Puyallup and Carbon River valleys to warn residents of volcanic eruptions and lahars (giant mudslides) from Mount Rainier.

Coastal communities, especially those in northern California, Oregon, Washington, Alaska, and Hawaii, use siren systems to warn of incoming . In 2011, the city of Honolulu created an Adopt-a-Siren website for its tsunami sirens. The site is modeled after Code for America's Adopt-a-Hydrant, which helps volunteers in Boston sign up to shovel out fire hydrants after storms.

Some U.S. volunteer fire departments, particularly in rural areas, use sirens to call volunteers to assemble at the firehouse. This method is being used less frequently as technology advances and local residents within earshot often file complaints with their town boards. Some areas utilize their sirens as a last resort, relying more on cellular and Pager technology; however, a decreasing number of rural departments are still outside the range of wireless communications and rely on sirens to activate the local volunteer departments.

Many college campuses in the U.S., especially in the wake of the Virginia Tech shooting, have begun installing sirens to warn students in the event of dangerous incidents. Sirens in the United States have been replaced by NOAA Weather Radios for advance warnings about future severe storms whenever people are inside cars or buildings.

Around mainly suburban areas of big cities like Bahia Blanca, Mar De Plata, Rosario, Cordoba and Comodoro Rivadavia, in police stations, fire stations, factories, weather stations, city halls and amongst common public neighbourhoods, warning sirens can be found. Most of the common models are a special model which isn't completely identified yet as of now, which however, looks like a vertical Klaxon GP6/10, a Mechtric MS22 or a vertically installed mechanical or electro-mechanical eight-, nine-, eleven-, or twelve-port single-tone siren, most of which have six rectangular horns and are most often identified as a Kingvox. They sound off for terrorism attacks, bushfires, dam leakages, chemical plant issues, life-threatening/extremely severe weather alerts which are certain to happen, incoming enemy attack and any other common natural disasters. Other models present in the country's warning system include Federal Signal, Elektror/Siemens, Whelen, Telegrafia, Klaxon and Hörmann. In extremely urban areas like Buenos Aires, most of the mechanical sirens which used to operate in a large amount were decommissioned and replaced with a smaller amount of electronic sirens, SMS alerts to phones and in some cases, as EAS alerts to TV. In some areas around the suburban areas of the big cities, over the years and since the 2010s, some sirens were decommissioned due to maintenance upkeep even though most of them remain active.

Two signals are commonly used. Here are the signals:

• General warning: Thirteen-second wind-up and alert with a six-second wind-down, which repeats three times. This signal is used if a public emergency is imminent.
• All clear: A 100-second alert to be used after a public emergency has been dealt with.

The all clear signal is mainly used during the nationwide siren testing in Argentine Volunteer Firefighters' Day on 2 June, and sometimes, in some sirens, the general warning is tested after the all-clear.

Some large-scale sirens are also deployed, like the Grifco Model 888, Grifco Model 777, and Klaxon SO4, which are used at fire stations for call-outs and at Sydney's beaches for shark alarms. Alarms are also used around prisons for breakouts and at many factories and schools to announce start and finish times.

A siren is located at the Kwinana BP plant south of Perth; this siren is tested every Monday. It is used to evacuate the plant in case of an emergency and can be heard in Kwinana and certain parts of Rockingham. It can also be used to warn of severe weather and potentially dangerous emergencies on the Kwinana Industrial Strip.

In South Australia, a number of Country Fire Service stations have sirens on or near the stations. These are only activated when the brigade are responding to bushfire or grassfire events and for testing. They are not activated for every call, only as a public alert for the presence of bushfires.

There are electronic sirens that include Whelen, Telegrafia, SiRcom, Klaxon and Grifco.

In Victoria, many Country Fire Authority stations have sirens installed that are used to summon volunteers to an emergency callout, as well as consequently alerting the local community of brigade activity. Due to a variety of siren models in use across the state, there are two signals that are used, differentiated by length:

• Emergency callout: Siren sounds for no longer than 90 seconds.
• Community alert: Siren sounds for no less than five minutes.

In Melbourne's CBD, there is a set of sirens installed to warn of attack and extreme flooding. These became necessary after the Bourke and Flinders St. attacks, where people were killed as a result of a person intentionally driving a vehicle into pedestrians. In Queensland, Whelen Vortex-R4 sirens have been installed as part of the Somerset Regional Council Flood Warning System. At nearby Grantham, Queensland, a Whelen WPS-2906, which features both warning tones and pre-recorded messages provides early warning in the event of flooding. As well, Cairns Regional Council have installed nine Whelen WPS-2900 series sirens to alert to a dam breach of the nearby Copperlode Falls Dam. A map of the system can be found here, as well as additional information. Other Whelen WPS-2900 series sirens can be found in a few towns around Queensland as well.

Warning sounds vary from area to area, including rising and falling notes and Morse code sirens. Communities with volunteer fire brigades use a continuous note on all sirens for civil defense, and a warbling siren on the fire station siren only for fire callouts. Civil defense uses a distinctive "sting" siren that is used by all radio stations nationwide, but is currently only used for civil defense sirens in Wanganui.

• List of civil defense sirens
• Emergency Alert System
• Fire alarm system
• Long Range Acoustic Device
• Rotary woofer

• target="_blank" rel="nofollow"> Air Raid Sirens – outdoor warning siren website (archived)
• Civil Defense Museum – Overview of sirens since their inception (archived)
• Los Angeles air raid sirens – Pictures of unused nuclear-era civil defense sirens still extant in Los Angeles, California. .
• The Siren Archive – Over 1,000 siren photographs coupled with a few recordings from around the world
• The world's loudest and largest sirens ever
• "Tocsin B", Canada's dry run of its Nuclear Warning System from 1961 (CBC Radio News Special, 13 Nov 1961)
• Toronto Star – The mystery of the air raid sirens
• Michigan Civil Defense Museum
• Old German World WarII Air Raid Siren YouTube
• British World WarII Air Raid Siren with all-clear YouTube
• Federal Thunderbolt 1000T air raid siren in alert signal YouTube