Switzerland's siren network
Switzerland has a nationwide siren network designed to alert people in danger. Flood alarms are used in areas downstream of dams and mean you should leave the danger zone immediately. In all other cases, the general alarm is triggered.
There are currently around 5,000 fixed sirens across the country to warn the public in the event of a general alarm. Close to 600 of them also serve as flood alarms. In addition to the fixed sirens, there are around 2,200 mobile sirens, which are used particularly in sparsely populated areas or where fixed sirens have failed.
In the past, sirens were operated mechanically or with compressed air; today they are electronic. Sirens must be able to continue operating during a power outage. In the case of a general alarm, stored energy must be sufficient for at least four signals (including repetitions) after three days without mains power. For the flood alarm, at least two signals must be possible.
Remote control enables centralised activation
Fixed sirens are generally triggered remotely (via Polyalert) by the cantonal police, but they can also be activated locally if needed. Switzerland’s federal structure means the system is not designed for all sirens to be triggered nationwide at the push of a single button – and in any case, a situation that would require this is considered highly unlikely. In the event of a large-scale incident, however, the National Emergency Operations Centre (NEOC) would be able to coordinate alerts quickly and effectively.
Two types of alarm signals
General alarm: a consistent rising and falling tone lasting one minute, repeated after five minutes. This alarm is used when there is potential danger to the population. It indicates that official instructions or announcements will follow via radio or the Alertswiss app. When the general alarm sounds, you should:
- Listen to the radio or check the Alertswiss app.
- Follow the authorities' instructions.
- Inform your neighbours.
Flood alarm: only used in areas downstream of dams. It consists of twelve deep, continuous tones, each lasting twenty seconds, with ten-second pauses between them. When the flood alarm sounds, you should:
- Leave the danger zone immediately.
- Follow local information leaflets and official instructions.
Further Information
Contact
Polyalert
Guisanplatz 1B
CH - 3003 Bern