BEIJING — Cities around the country that have installed energy-efficient traffic lights are discovering a hazardous downside: The traffic signal light lens don't burn hot enough to melt snow and can become crusted over in a storm — a problem blamed for dozens of accidents and at least one death.

"I've never had to put up with this in the past," said Duane Kassens, a driver from West Bend who got into a fender-bender recently because he couldn't see the LED traffic lights. "The police officer told me the new LED traffic signal light weren't melting the snow. How is that safe?"

Many communities have switched to LED traffic light core in their traffic signal lights because they use 90 percent less energy than the old incandescent variety, last far longer and save money. Their great advantage is also their drawback: They do not waste energy by producing heat.

Authorities in several states are testing possible solutions, including installing weather shields, adding heating elements like those used in airport vehicle lights, or coating the lights with water-repellent substances.