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UPDATED: March 15, 2012 11:29:18 AM EDT
About the Sirens

About the Sirens

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When the Sirens Will Sound

The sirens will only sound if the University issues an Emergency Warning because of a significant emergency or dangerous situation involving an immediate threat to health or safety:

  • An armed and dangerous person on or near campus;
  • A major chemical spill or hazard;
  • A tornado warning for Chapel Hill and Carrboro; or
  • A different emergency, as determined by the Department of Public Safety.

What to do

Be prepared to:

  • Seek shelter inside now.
  • Close windows and doors.
  • Stay until further notice.

In the case of a tornado warning:

  • Seek shelter immediately.
  • Move to an interior room on the lowest floor of a sturdy building.
  • Avoid windows.
  • If no shelter is available, lie down in a low-lying area.
  • Protect yourself from flying debris.

The sirens also broadcast short pre-recorded voice messages. When the threat is over, the sirens will sound again with a different tone to announce along with the voice message:  "All clear. Resume normal activities." The timing will depend on how fast emergency responders can determine that a threat is over.

What the sirens sound like

People on or near campus can expect to hear two different sounds - one to signal immediate action (such as go or remain inside) and another to indicate all clear.

Listen to an audio sample of the siren tone.
Listen to an audio sample of the siren "all clear" tone.  

Siren locations

People outside on or near campus may hear the sirens at six locations:  Hinton James Residence Hall off Manning Drive; the Gary R. Tomkins Chilled Water Operations Center behind the Dogwood Parking Deck; Winston Residence Hall at the corner of Raleigh Street and South Road; near Hill Hall behind University Methodist Church; University buildings and support facilities near the Giles Horney Building off Martin Luther King Boulevard; and near the William and Ida Friday Continuing Education Center about three miles east of the central campus.  If you are inside a building or driving in a car, don't expect to hear the sirens.

Siren technology

The University's siren system was purchased in spring 2007 from Federal Signal Corp., following about two years of discussion and planning. The system was designed to deliver high-intensity warning signals over a large area using omni-directional speakers. Those speakers are capable of producing a high sound level while making moderate demands on the battery power source. Activation is by dedicated radio frequency and the sirens run on batteries that are continuously charged by a solar panel on each siren pole. The sirens are mounted on poles that are 40 feet from the ground. These characteristics ensure continuous operation regardless of power outages.

Distance for the siren tones

Federal Signal Corp.'s product specifications indicated that the signal from each of the five siren locations could be expected to carry approximately one-quarter to one-half a mile. The system is designed to be most effective for people outside. Most people inside buildings or in cars or vehicles likely will not hear the siren sound. The product specifications also indicate that the sirens would be heard at a 121 decibel level at 100 feet away. The minimum sound level is 80 decibels.


The UNC Department of Public Safety will activate the sirens when an Emergency Warning is issued based on conditions on campus or that emergency officials believe will affect campus. The Information Technology Services Control Center can also activate the siren on behalf of public safety if conditions warrant. The siren will only sound if the University issues an Emergency Warning because of a significant emergency or dangerous situation involving an immediate threat to health or safety, or during testing.

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