Why Are Some US Street Lights Turning Purple?

I saw it for the first time in Wichita, Kansas. My coworker was driving a shuttle carrying myself and a few students from a guest speaker event, and I noticed something strange—a purple street light.

I initially brushed this off as some weird mishap, but as we drove on I noticed dozens of purple street lights throughout the city.

We started brainstorming ideas in the car. Maybe purple was the color of one of the local high schools? Maybe there was some sort of disease awareness month we were unfamiliar with? Did it have to do with environmental concerns?

We abandoned most of those ideas for a simple reason—the lights seemed too unsafe to be explained by any of those reasons. It’s possible that the purple lights were just as bright as normal lights, but the problem isn’t the brightness. Drivers aren’t used to a monochromatic purple-hued environment, and it was obviously difficult for the driver to adjust. In some ways it seemed worse than having no street lights at all.

After searching, I found reports from other cities. Lots of local news stations chronicle the mystery of the purple lights. Ultimately, the presence and pervasiveness of the new purple lights is best understood with two explanations: one technological and one political.

After doing some digging, I found the initial explanation. Adam Rogers writing for Business Insider documents how one firm, Acuity, dominates the Solid State Lighting (SSL) market. SSL systems are systems which incorporate LED light in a particular way which is often considered advantageous for things like street lamps. Rogers says, “every city with purple lights that responded to my queries or has public records on the matter bought its LED lights from Acuity.”

So what was the issue? Well, Rogers talked to a representative from the City of Vancouver who says the cause is ultimately an issue with a defect unique to LED lighting. “There's a laminate on the fixture that gives it its white color. As that laminate began to degrade, it caused the color tint to change toward purple."

In one sense, this is our answer. A company seems to have had a manufacturing defect which is causing a new technology to glitch leading to purple roadways.

But this explanation falls short of answering an important question: why does one firm have so much effect on the lighting of the US (and Canada)?

Acuity was the largest manufacturer of lighting by market share in 2017 when the bad bulbs began to be created, according to research by Rogers.

It’s unclear how much Acuity dominates access to municipal markets based on the data, but the widespread presence of this defect suggests it has a decent amount of influence as a contractor for government at local and state levels.

Why is this the case? Well, the market for government lighting is a winner-take-all discussion. Street lights tend to not be purchased individually. Rather, governments at various levels accept bids for companies to create products on a large scale.

So say a city government wants to update its old street lights with new LED technology. It’s not as if agents shop at the discount street light store. They solicit companies who will provide the street lights, and the winner gets the whole project.

This sort of environment creates a scenario where a few winners begin to dominate the market, and smaller companies simply can’t compete for these larger projects.

Compare this to your own light bulb selection criteria. Do you select one brand of light bulb to light your entire house? Most people don’t. Instead myself, and many others, buy light bulbs one pack at a time based on who gives us the best deal.

This doesn’t mean a single company will dominate all lighting. Competition is more robust than that. But government contracting does lead to markets which are likely more concentrated than they would be if not for the contracting.

Without contracting, perhaps individuals or neighborhoods would work with private companies to provide lighting they are willing to pay for. It’s difficult to imagine exactly what this would look like, but “less centralized” seems like an intuitive answer.

This issue is only compounded by the fact that new government regulations to ban incandescent bulbs are now in effect. Changes like this further harm competition by preferencing companies more able to adapt to arbitrary energy efficiency criteria.

So if you’re driving along at night and your vision is obscured by a strange, purple hue, remember that, although the light was the result of a manufacturing mistake, the impact of the mistake is predictable when you consider the incentives at play in government contracting.

Peter Jacobsen is a Writing Fellow at the Foundation for Economic Education.

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