Why are there purple lights on the Triangle Expressway?

Driving You Crazy

RALEIGH, N.C. (WNCN) – A stretch of the Triangle Expressway is lit up purple and it’s driving one Raleigh driver crazy.

CBS 17’s Laura Smith reached out to the North Carolina Department of Transportation and found the color is due to a manufacturing defect.

A coating on the fixture’s bulb is causing the light to shift to purple.

More of ‘What’s driving you crazy on the roads?’

Marty Homan, spokesman for NCDOT, said they are aware of the issue and taking corrective action.

“In order to produce the white lights from LED chips, manufacturers have to add a filter to the lens of the LED. In most cases, that filter is a layer of phosphorus of varying thickness for the different colors of light. For the fixtures that have color shifted to purple, there was a manufacturing defect which causes the phosphorus layer on the LED chip to burn off,” said Homan.

A video sent to CBS 17’s Laura Smith shows at least a dozen lights shining purple at the NC-540 toll and U.S. 1 interchange in Wake County.

American Electric Lighting is providing replacement fixtures to NCDOT.

“These lights were installed by our contractor as part of our statewide LED upgrade. Fortunately, the Triangle Expressway is the only place where NCDOT owned and maintained fixtures with this identified defect were used,” said Homan.

He said a contractor has been secured to begin the replacement of the fixtures that have color shifted.

“That work should be starting relatively soon,” said Homan.

Duke Energy is also dealing with a purple lighting issue.

“With our lights, it was the result of a manufacturer defect of one batch of LED streetlights and represented less than a fraction of 1 percent of our streetlights,” said Duke Energy spokesman Jeff Brooks.

If you see a light switched to a deep purple tint report it to Duke Energy and request a light repair.

In a statement to CBS 17, a spokesperson with American Electric Lighting said, “As always, we stand behind the quality of our products, and we have been proactively working with customers who have experienced the issue to address any concerns.”

The lighting company said the purple light output is in no way harmful or unsafe.

If you have something driving you crazy on the roads and you want our Laura Smith to get you answers, email her at Lsmith@cbs17.com

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