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Law enforcement officers often use flares to point out an accident location or other traffic hazard and increase visibility.
However, the magnesium-based highway flares traditionally used by law enforcement can create great risks for officers and the surrounding area. These flares burn at high temperatures for 15 to 30 minutes, creating smoke and fumes that can overwhelm the user. Once the flare has finished burning, the officer is left to dispose of the hot, melted remains. Besides the immediate risks, there are potential long-term effects on the surrounding environment. For example, the byproducts of burning flares can poison a nearby water supply.
"Most agencies do not have policies about the disposal of flares," said Charlie Mesloh, director of the Weapons and Equipment Research Institute at Florida Gulf Coast University. "It's completely discretionary. Officers frequently kick them to the side of the road, leaving sharp metal spikes that can create a future road hazard."
With funding from NIJ, Mesloh and his colleagues assessed alternative highway flares that use chemical or electric sources of energy, thus reducing the risks posed by traditional flares.
The research team found the chemical and electric flares tested were less visible than the traditional flare when placed at ground level. Sometimes, minor depressions in the roadway were enough to obscure the alternative flares. However, when researchers lifted these flares off the ground — even by just a few inches — visibility increased by one-fourth of a mile. When placed on a cone, the alternative flares were visible at one mile or more.
"When you increase the ability of people to see at greater distances, you give them more time to react," Mesloh said. "The most dangerous time for officers at an incident scene is when they are setting up the flares and cones.
Officers need to be able to set up the flares quickly, efficiently and in such a fashion that drivers understand what to do."
In addition, the researchers found that basic, uncomplicated designs for cones and flares were the most effective and visible. Arrangements using multiple flare types disoriented and confused other drivers.
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