"Energy-Efficient Traffic Lights Can't Melt Snow," with the subhead, "Traffic accidents are blamed on energy-efficient traffic lights getting covered with snow."

The report noted that during an Illinois snowstorm last April, one motorist, Lisa Richter, could see she had a green light and began making a left turn. A driver coming from the opposite direction did not realize the stoplight was obscured by snow and plowed into Richter's vehicle, killing her.

The severity of a storm is a factor, said Lonnie Tebow, director of the Newark, N.Y.-based International Municipal Signal Association's (IMSA) Transportation & Traffic Programs Office. "I spoke with IMSA-certified traffic signal maintenance supervisors and managers in the Denver, Colo.; Toronto, Ontario; and the Indianapolis, Ind., metropolitan areas of the U.S. and Canada. They told me, frankly, that it was really not much of a problem in any but the most severe snowstorms," Tebow said.

Traffic signal crews take a variety of steps to clear LED signals, added Tebow. "On those rare occasions and at those few locations where snow drifted over LED signal indications, several agency personnel told me that they used Super Soaker-type squirt guns filled with anti-freeze or some similar-acting chemical to melt the snow from the lens without ever needing to leave the ground. Most of the others simply wiped the lenses clean with a rag or brush from an aerial truck. And as a preventative measure some agencies were applying a chemical compound like Rain-X to the signal lenses."

Manufacturers are developing products that melt snow on LED signals, said Tom Griffiths, publisher of LIGHTimes Online and Solid State Lighting Design. "If you put in the heating elements that would then remove the occasional snow situation, then you start to get rid of the power advantage of LED signals compared to incandescent signals."

That power advantage can be huge, Griffiths said: "Typically, you see 90 percent energy efficiency in LEDs compared to incandescent." LEDs are also more dependable, Griffiths said: "The LED traffic signals seem to have an incredible ability not to fail (seven-plus years and counting for many). Incandescents failed regularly."

Fama Traffic, of www.ledtrafficlight.cn, offered this traffic safety tip for motorists: "If there is a problem (with snow obscuring an LED traffic signal), then there are laws in place that say that motorists treat that non-working traffic signal as a stop sign. So, it probably is not that much of a safety concern in the long term."