An Unforeseen Problem With LED Traffic Lights

During a snowstorm last week, the Minnesota State Patrol responded to over 1,200 crashes and spinouts around the state. Fifty people were injured, and one woman was killed.

Part of the problem, of course, was the slick roads. But there was another problem—an unexpected one. The state's Department of Transportation has been in the process of replacing the traditional incandescent traffic lights along state highways and roads with the much more energy efficient LED lights. The goal, of course, was to save money.

But that transition has come at a safety-related cost. While incandescent lights generate enough heat to melt snow, sleet and ice that might hit the traffic light covers, the LED lights do not. As a result, snow, sleet and ice can accumulate on the covers, eventually obliterating the lights that are emanating from the LEDs.

So, instead of seeing green, amber or red, motorists see white, white and white. And that has caused some problems with many motorists assuming they have green lights and moving through intersections, crashing into other vehicles whose drivers do (or also think they do) have green lights.

"This is a common issue anywhere there are LED lights and snow and ice," said Kevin Gutknecht, director of communications for the Minnesota DOT.

The problem is not unique to Minnesota. It is becoming more common in most northern regions where governmental agencies are switching from incandescent to LED traffic lights. An article published by the Canadian Broadcasting Corporation (CBC) last year reported on a school bus in Windsor, Ontario, that ran a red light and broadsided a vehicle at the intersection. Six students, a school staff member, and the drivers of the car and bus were taken to the hospital. The bus driver reported that the red LED traffic light was covered in snow.

There are a number of possible solutions, including heating the signal heads, installing shields or clear covers that prevent snow and ice buildup, or installing special circular guards around the lights to deflect ice and snow.

In the meantime, most communities experiencing problems with snow-covered LED traffic lights simply arrange for work crews to drive to each light pole, remove the snow and ice by hand, or, if possible, simply shake the poles to loosen the snow. Communities also ask motorists, if they approach a snow-covered traffic light and are unable to see the color that is in effect, to treat the intersection as a four-way stop.

As for Minnesota in specific: "We want to get this fixed as soon as possible," said Kent Barnard, a spokesperson for the Minnesota DOT.

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