Jan. 8, 2010 -- A huge swath of the country is getting snow and it's raised an unusual and potentially dangerous problem for motorists.

Communities across the country are converting to LED traffic lights, but these lights don't emit heat, so snow doesn't melt like it would with a regular incandescent bulb. In some cases, Drivers then can't see the signals.

During a snow storm last year, Lisa Richter of Oswego, Ill., had a green light and was turning left. But police say a driver in the oncoming lane blew through his red light and plowed into her, killing her instantly.

This wasn't a regular accident. Police said this traffic light, blocked by snow, contributed to the crash. The light was an LED signal, which doesn't emit heat, so snow doesn't melt like it would with a regular incandescent bulb.

Cities and states across the country that have converted to LEDs report an energy cost savings of up to 80 to 90 percent.

In Green Bay, Wisc., where all traffic lights are now LEDs, December's incredible snowfall caused many to be packed with flakes.

After their intense storm last month, some drivers in Madison, Wisc., noticed their neighborhood LED signals were hiding.

"I know that the stoplights are there, but if I didn't, it would have been very easy to fly right through them," one driver said. "And especially with the off ramp right on the interstate, it could be a very dangerous situation."

The state of Wisconsin switched to LEDs in 2002 to achieve the massive energy cost savings. Maintenance costs are also much lower because LEDs last a long time. Incandescent bulbs usually have to be replaced every 2 years.

"With LEDs, we have some of our heads that were installed in 2002 still operational today," said Wisconsin state traffic signal systems engineer Joanna Bush.

Another advantage of LEDs: Bush said the old incandescent bulbs could pose safety problems of their own.

"When they fail, they go dark, like a light bulb at your house. There's no warning and it's dark. With the LEDs, it's a string or two that starts to go out and the driving public might not even notice a change in the LEDs and we can get our crews out to change it."

Creative Solutions, Cautious Driving

To guard the lights against snowfall, Wisconsin is testing out snow shields, which give the otherwise flat LEDs more shape.

The shields run about $40 a piece. Because of the steep price, the state may initially install the covers only on its red LED lights -- the color that's most vital in preventing an accident.

In the meantime, the Department of Transportation uses big sticks to clean off the lights when it gets calls from drivers who complain.

Rather than go back to incandescent bulbs, some officials see an opportunity for creative solutions - like the snow shields and better-designed visors. Officials say cautious driving is the other part of the equation.

"You will get your green. It's just a matter of watching the cues of the vehicles around you to find it," Bush said.

It turns out the same problem can also occur with the yellow bulbs on old-fashioned incandescent traffic lights.

The yellows are up for a much shorter time than reds or greens, so they don't have as much time to heat up and melt the snow.

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