Redundancy in an Emergency

Emergency sirens begin to blare from atop poles scattered across a city or a university campus.  No doubt there is an emergency.  But is it an approaching tornado?  A flash flood?  A toxic chemical spill?   A terrorist attack?  It may be one of...


Emergency sirens begin to blare from atop poles scattered across a city or a university campus.  No doubt there is an emergency.  But is it an approaching tornado?  A flash flood?  A toxic chemical spill?   A terrorist attack?  It may be one of dozens of other scenarios, each of which might require a different response from citizens or students.

According to Mark Nelson, manager of business development for ADT Security Services, sirens are very good for one thing – gaining a person’s attention.  But without more information, a siren may do more harm than good.

“That’s where mass notification systems play a major role,” he said.  “And rather than relay on one single technology, it’s best to take advantage of redundant systems that increase the likelihood that information will reach people when they most need it.”

Nelson said a Web-based system can simultaneously send thousands of messages to people’s cell phones, landlines, PDAs, laptop and desktop computers, giving residents and students immediate information and instructions on what protective action to take. 

But during an emergency, both wired and cellular phone lines may become overloaded and temporarily crash.  That’s when other systems continue to provide vital instructions.

Outdoor voice communications systems utilizing specialized speaker technology provide intelligible voice commands that can be clearly heard up to a quarter-mile away, Nelson said.  These speakers can be permanently mounted on poles or buildings or on a trailer for portability. 

Nelson said there are other ways to inform people during an emergency.  LED signage can be used to alert drivers about to enter a dangerous zone.  Many college and university campuses have their own radio and/or television stations that can be called upon to broadcast emergency announcements.  On a city or county level, broadcast and cable-based television and radio stations could be asked to help disseminate information.

“In an emergency, when people are in danger, information is extremely critical,” he said.  “By using redundant systems and outlets, lives may be saved and property damage limited.”

-- PSW staff