For the general warning of the population, the safety and civil protection authorities resort in particular to the following means:
- Official danger announcements and danger notifications via radio,
- sirens, which can also be used to broadcast the signal "switch on radio and listen for announcement",
- Public address vehicles,
- Warning apps.
In the event of disasters, other damage events below the disaster threshold and large-scale hazard situations, as well as in the event of siren false alarms, it may be necessary to warn or inform the population on a supra-local basis. For this reason, the security and disaster control authorities as well as the police can arrange for announcements to be made via radio using a defined procedure; subtitling on television is also possible.
In the case of radio announcements, a distinction is made between official danger announcements, which are broadcast immediately and in wording by the radio stations, and danger notifications, which provide information at the next possible opportunity (e.g. in the news) about expected dangers, damage situations and, if applicable, expected consequences.
Official danger announcements or danger notifications are usually passed on to the radio stations connected to the traffic warning service via the police operations centers. In the case of warnings about forest fires or severe weather, these are given directly to the radio stations by the German Meteorological Service.
Sirens are also used to warn the population, primarily in areas or in the vicinity of facilities with a particular risk potential.
Bavaria has defined the meaning of the siren signals used in Bavaria with the Ordinance on Public Acoustic Signals. The most important siren signals are
- the alarm in case of fire and other emergencies, which serves to alert the emergency forces of the fire departments.
Signal: three times in the height constant tone (continuous tone) of twelve seconds duration, with twelve seconds pause between each tone.
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- the alarm intended to prompt the population to pay attention to radio announcements on the occasion of serious threats to public safety.
Signal: rising and falling wailing tone of one minute duration.
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In areas where sirens are available to warn the population, the public is usually informed from time to time about the siren signals and their meaning in brochures or on the Internet sites of the competent authorities. In addition, a nationwide siren rehearsal takes place twice a year, in which every municipality that has appropriate sirens can participate. This siren test alarm serves not only to test the function of the siren, but also to inform the population about the significance of the siren signal in preparation for broadcast announcements.
In addition to radio announcements and sirens, loudspeaker vehicles and increasingly smartphone apps are also used to warn the population.