Around 8,200 sirens in Switzerland
There are currently arround 7,500 (P&S) sirens in Switzerland today. Distributed throughout the country, they are sounded when the General Alarm is raised. 4,700 are stationary (positioned on rooftops) and 2,800 are mobile. These can be mounted on cars and are for use in remote areas. Areas close to hydroelectric dams have special Water Alarm sirens, which are fed by emergency generators. There is a wide range of approved sirens; some of the new models can be used to sound both alarm signals.
The older sirens are powered mechanically or using compressed air. The new siren systems are electronic. According to the system specifications, there must be a sufficient store of energy five days after a network interruption to emit at least four General Alarm signals (including a repeat). For the Water Alarm, there must be sufficient energy to emit at least six signals.