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The Buzz: Installation Spotlight: Advanced Mass-notification System, Arlington County and City of Alexandria, Va.

Nov 1, 2007 12:00 PM, By Charles Conte

Emergency Response

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Pilot Program Background

The County of Arlington, Va., and the City of Alexandria tested part of their pilot program outdoor emergency warning system on the streets of Alexandria on May 18, 2007. The outdoor warning system is from MadahCom, and it is integrated into Arlington’s emergency warning systems. MadahCom chose CJ46 horns from Atlas Sound as best suited for three fixed tower locations, out of 10 tower locations in the program.

The Sept. 11 tragedy, hurricanes Katrina and Rita, and the recent Southern California wildfires suggest that there may very well be a need for a loudspeaker broadcast system to reach people who might not receive emergency warnings from other sources. This is the premise that Arlington County, Va., and the City of Alexandria have been testing in recent months in a pilot program that Arlington is managing on behalf of the National Capital Region.

The outdoor warning system is from MadahCom of Sarasota, Fla., an established supplier of mass-notification systems to the U.S. government. The outdoor warning system is one component of the region's integrated indoor and outdoor warning system, known as MadahCom's Wireless Audio Visual Emergency System (WAVES), and it will supplement the region's many other emergency-notification systems.


The most recent demonstration of the system in May of this year involved five loudspeaker tower locations out of 10 locations in the pilot program.

“Three of these locations have six horns in various stacking options,” says Alan Avidan, senior VP of MadahCom. “These were the more ‘urban canyon’-style locations, and required more directivity control of the loudspeakers.”

MadahCom chose the wide-dispersion CJ46 reflex sound horn from Atlas Sound for its “nice combination of directivity pattern control, good fidelity, and price,” according to Avidan. The other seven tower locations in the program have MadahCom omnidirectional loudspeakers. The system can be tested silently as well, without disturbing residents.

“Installing a system in the middle of a busy urban area required good coordination and caution,” Avidan says. “Arlington County and the City of Alexandria provided excellent assistance.” Selecting the exact loudspeaker array type and location that would work best with the acoustic environment required expertise that both MadahCom and John Fuoto (consultant to Arlington County) provided with excellent results. MadahCom RF engineers worked hard to overcome some terrain difficulties. Cooperation from both the county and private institutions was a necessity for the sake of improving the safety of Arlington County's and Alexandria's citizens and visitors.

The National Capital Region's emergency managers wanted to see how effective the outdoor warning system was in reaching people who are away from television, radio, computers, and telephones and do not have mobile devices, as well as people in transit, attending outdoor special events, or visiting the National Capital Region. Sound tests by Arlington County's emergency managers (performed on May 18) indicated intelligible sound reproduction from tower speakers, Avidan says, with some fluctuations as the result of transient ambient noise such as aircraft and buses. “Test listeners reported hearing the alerting tone and the test messages quite clearly,” he says. Both random word sequences and coherent sentences were played in English and in Spanish. A group of volunteers spread around the county recorded the results.

“We have a robust ‘system of systems,’” says Robert Griffin, director of Arlington's Office of Emergency Management (OEM), “including Arlington Alert [which sends emergency alerts and notifications to participants by email and text and voice messages] and 1700AM Arlington [an emergency radio station], that allows us to get important information quickly to those who live and work here, as well as visit.”

The WAVES system can be activated in specific neighborhoods only, enabling police to help look for a lost child, for example. “This outdoor warning system is another important tool in our emergency communications arsenal,” Griffin says.

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