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Bozeman, MDT address 'bright streetlight problem' in area through study

City engineers say several locations across Bozeman will be dimmed
Posted at 2:35 PM, Feb 03, 2020
and last updated 2020-02-03 16:35:27-05

As the city of Bozeman grows, so does the need for street lights. But some recently installed street lights are causing problems.

“The national standards, frankly, haven’t caught up with the technology,” says Shawn Kohtz, city engineer for the City of Bozeman.

Kohtz says issues with brightness started nearly three years ago.

“We changed our street lighting standard from high-pressure sodium-based light to an LED light and the reason why we did that was that LED lights are a lot more efficient,” Kohtz says. “It turns out we don’t need as much light with LED lights to actually see the road effectively.”

That change also saves roughly 50 percent of energy in the process.

“There was a reduction in the carbon footprint equivalent to about 18 passenger cars for a full year,” Kohtz says. “The LED lights look a lot brighter and, as it turns out, the LED light quality is very similar to the color of the moon, moonlight, and as you can imagine, our eyes adapted to nighttime vision with moonlight so we can see much more effectively with LED light.”

But then came complaints. Last September, homeowners living along Love Lane filed a petition to MDT about their own newly-installed lights.

And back in town, Kohtz says about a dozen intersections were too bright, as well.

“Some people were saying we are overlighting our streets and so, as a result, the city commission ordered a study that said, hey, let’s go take a look at our street lights and determine what we need to do with our standards going forward,” Kohtz says.

MDT has revisited the stretch of road, putting diffusers on the lights and lowering the levels to try to help the problem. But across the city, they had more than 750 lights to check with 12 sites, intersections, coming back too bright.

According to the study, engineers point out that intersections like Baxter and Ferguson were far brighter than that standard with a recommendation: turn them about 40 percent of the way down.

It’s a process, but Kohtz says it is now on paper and underway.

“We’ve heard and responded to some of the complaints that were out there and, going forward, we’re updating our standard,” Kohtz says.

Kohtz says NorthWestern Energy actually owns and maintains a majority of the city’s lights, somewhere around 1,100 of them.

He adds they plan to start converting about 500 of them to LED light and a better standard this year.