'Hard on the eyes': Defective streetlights on some Calgary roadways have drivers blue

Why are some Calgary streetlights turning blue? Streetlights along some of Calgary’s busiest roads are turning blue. But do you know why they’re that colour? Kevin Green explains.

Parts of Stoney Trail in northwest Calgary resemble a teenager's bedroom -- bathed in black light.

Scores of streetlights along some of Calgary's biggest roads are turning a deep blue, nearly purple colour.

"They are kind of a distraction," said driver Mandir Singh.

"I have no idea why they are like that."

Calgarians have a lot of theories, ranging from blue light being used to keep drivers awake, to the lights possibly being black lights, causing road markings to fluoresce.

The real answer is more prosaic: they are defective.

"The LED is basically a blue LED, which is then covered with a phosphor material. This phosphor material is responsible for absorbing the blue light from the blue LED, and remitting some of that blue light in terms of red and green light. And then, when those three things combine -- the red, the green and the blue -- our brain tells us that it is white," said Kartikeya Murari, professor of biomedical engineering at the University of Calgary.

"The phosphor material in these lights is what is getting damaged in some way. It looks like it's sort of just physically coming off of the LEDs, and that results in the blue portion of light dominating over everything else."

Many drivers say the blue light is distracting and makes it hard to see on the roads.

"You can't see anything, especially in fog. You can't see the road. You can't see the signs," said Meagan Bos.

"It's very hard on the eyes."

Murari says that's not just a perception -- there's hard science showing we don't see as well in blue light.

"We can see blues, reds and greens, and green is in the middle, so it happens that our vision is most sensitive in that wavelength. So that is one issue, in that we don't see well in blue. The other is colour perception," Murari said.

"Under blue light, if you take something that is green or red, both of these will look like something that is black, or dark-coloured. We will not be able to separate out these colours."

Murari says that makes the defective LEDs suboptimal for on-street lighting.

Despite that, the province has no plan to fix the problem.

"In Calgary, roughly 70 of the 7,000 LED streetlights along the Calgary Ring Road and Deerfoot Trail are showing a blue colour. These lights were installed about seven years ago and are no longer under warranty," Alberta Transportation spokesperson Jesse Furber said in a written statement to CTV News.

"Transportation and Economic Corridors continues to monitor the streetlights to see how they perform. Lights are being replaced as they burn out, but at this time there are no plans to replace the blue lights."

That doesn't sit well with some Calgary drivers.

"Our province has enough money to spend what, eight million bucks on advertising in Toronto for all sorts of things? But we can't fix a few lights in our own backyard?" said Ron McMahon.

"It's like we have all sorts of money to do things but we don't have money to take care of our own home."

The province notes similar problems have happened in other jurisdictions across North America and Europe.

In 2021, streetlights in Vancouver began turning blue.

In that case, the bulbs were still under warranty and the manufacturer replaced the defective units.