CHICAGO (CBS) — Energy-efficient traffic lights have been creating hazards at some intersections, because blowing snow was able to cover up the signals, and prevent drivers from seeing whether it’s their turn to go.

LED traffic signals don’t emit as much heat as older incandescent lights, so they don’t as easily melt snow in winter.

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When the snow is heavy, and wind is blowing hard enough, snow can pack onto LED traffic lights and prevent drivers from seeing the signals.

A spokesman for the Chicago Department of Transportation said the city has 2,200 intersections with LED signals, out of 3,100 lighted intersections in the city.

“This phenomenon doesn’t occur often, and generally is only with heavy blowing snow like we saw last night,” CDOT spokesman Peter Scales said.

Scales said drivers should call 311 if they see a traffic signal covered by snow.

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Nicole Winslade, a visiting nurse, said she spends a lot of time on the road, and it was an adventure on Wednesday as she drove from the North Side to the South Side.

“The traffic signals that control the southbound lanes of traffic are either completely or partially obscured with this wet, sticky snow we had last night,” “I have seen a couple of close calls, with cars accidentally running red lights, and I have to admit I came awfully close myself.”

She said it makes her very nervous, and has made her a lot more defensive behind the wheel.

“Even if I’m not going southbound, and a hazard myself, if I’m going in any other direction, I don’t know that the other people are going to stop in time,” she said.

Stop signs even ended up coated in snow on Wednesday, left discernable only by their shape. Street signs were covered, too, making it difficult for the uninitiated to determine exact locations.

Many cities have replaced most of their old incandescent traffic lights with LED lights to save on money. The LED lights have been around for years, so problems with snow are not new.

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One low-tech fix involves replacing the standard sun visors on the signals with vented visors that are open on the bottom, and less likely to hold snow.