Mystery horns

[Conky 2000]

http://www.youtube.com/watch?v=9vUmKYq39NU
Can anyone tell what kind of horns those are? Yes, they are horns, not sirens.

[JasonC]

Sounds electronic. At many of these, they just sound the siren on a police car. I believe there is a law requiring the sounding of a siren, horn, or whistle anytime something is blown up with explosives. This goes for many things, not just building implosions.

[Jim_Ferer]

From the OSHA regulation at 1926.909:

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1926.909(e)

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TABLE U-1
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WARNING SIGNAL - A 1-minute series of long blasts 5 minutes prior to
blast signal.
BLAST SIGNAL - A series of short blasts 1 minute prior to the shot.
ALL CLEAR SIGNAL - A prolonged blast following the inspection of blast
area.
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