SirenWallonia
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103. Siren
A siren is a loud warning device used to attract attention and warn people that an emergency or priority vehicle is approaching. Sirens are commonly fitted to vehicles such as ambulances, fire engines and police vehicles and may produce alternating or changing tones so they can be recognised quickly.
When an emergency vehicle approaches with its siren operating, road users should remain alert, identify where the vehicle is coming from and safely make room for it to pass. The exact priority rules and permitted use of sirens vary between countries.
Wikimedia.org • David R. Tribble • CC BY-SA
When may an emergency vehicle use its siren in Belgium?
A priority vehicle may use its special audible warning device only when carrying out an urgent mission.
What must you do when you hear an approaching emergency siren in Belgium?
You must immediately clear the way and give priority to the approaching priority vehicle. If necessary, you must stop.
Is an emergency siren the same as an ordinary vehicle horn in Belgium?
No. The special audible warning device of a priority vehicle is subject to specific emergency-vehicle rules. Ordinary sound signals must be kept as short as possible and are generally permitted only when necessary to prevent an accident or, outside built-up areas, to warn a driver who is about to be overtaken.

Traffic rules
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