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New LED Traffic Lights Too Cool.. and thats not cool December 21, 2009

Posted by Dr. Z Bulbs in Controversial information, LED Lights.
Tags: , , , , , , , , , , , , , , ,

Zoinks! LEDs have been all the rage as of lately but seems some applications are working out so smoothly. Check out this article from the Detroit Times that discusses the danger of LED traffic signal lamps.

Dr. Z


New traffic lights too cool
They save energy but emit less heat, so snow may block signal
Tom Greenwood / The Detroit News
Some northern states are reporting a problem with light-emitting diode traffic lights: The cool burning LEDs don’t generate enough heat to melt ice and snow that accumulates in front of the lenses on the signals.

Although there are no LED-related reports of crashes or deaths in Michigan, the problem has reportedly led to dozens of accidents in other states.

But the situation is still being addressed, said Utpal Dutta, professor of traffic engineering at the University of Detroit Mercy.

“We are working on the problem,” Dutta said. “We may put a longer shade on the light to shield it from ice and snow, but we’re not sure about putting a heater into the light. A heater would cost us money to run the lights, which we don’t want to do.

“But we will come up with something down the line. In terms of energy and life cycle savings of LEDs, this is a tiny problem.”

On the rare occasion when an LED signal is covered with snow, responding work crews simply clear it with a blast of compressed air.

Longer lasting lights
Road Commission for Oakland County spokesman Craig Bryson said LEDs are still better than traditional lights because they need to be replaced only once every seven years.

“There were a lot more times where there were traffic signals with burned-out bulbs than there are signals with snowy LEDs,” Bryson said.

The LEDs used in traffic signals aren’t really a single bulb but are actually arrays of hundreds of individual electronic lights about the size of a pencil eraser.

The appeal of the lights is that they use up to 90 percent less energy, last longer and burn brighter than traditional bulbs.

For Franklin residents George and Madeline Haddad, snow on LED traffic lights hasn’t been a problem.

“We’ve never encountered that problem when we’re on the road, and it really isn’t something I’m worried about,” George Haddad said. “I can’t ever remember seeing traffic signals blocked by ice and snow.”

Bryson said a number of circumstances have to merge for the LEDs to be obstructed by ice or snow.

“The wind has to blow at a certain speed and a certain angle to end up in against the lens,” he said. “Plus the snow has to be wet and heavy. This problem happened with the old bulbs as well.”

Cost only factor in switching
William Taylor, professor emeritus of civil engineering at Michigan State University, understands how the LEDs can be driving problem in snowy weather.

“It kind of makes sense that they could cause a snow problem because they’re so efficient that it doesn’t make all that much heat,” Taylor said.

“But should we switch back to the old incandescent bulbs? Only if it eventually costs more for crews to clean off the LED lights than they would save in energy costs.”

LED traffic signals are common on the MSU campus, Taylor said.

“But as a driver, I’ve never noticed any problems with them,” he said.



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