Some Mesa neighborhoods may one day get a better view of the stars as the city converts some 34,000 sodium vapor street lights to more advanced LED lights.
Officials plan to create more lighting options with four lighting zones that vary from so-called “dark sky’’ conditions in northeast Mesa to plenty of brightness in busier areas.
The conversion won’t happen overnight.
But it eventually will allow officials to dim the lights anywhere from as little as 25 percent of maximum capacity in Desert Uplands and Lehi to 45 percent in downtown and other areas with more vehicle and pedestrian traffic.
Using city crews to save money, the conversion will take about seven years.
If the City Council approves the full plan Dec. 2, the cost would be close to $17 million with the dimming option.
The plan would replicate and expand the lighting conditions that existed during a four-week pilot program in Lehi, Desert Uplands, and on Fraser Drive in central Mesa.
“I know there are a lot of residents of Desert Uplands that are passionate about lighting. I think these are great recommendations,’’ Councilman Dave Luna said.
He said many people in northeast Mesa would prefer no lights, but some are needed along major streets for public safety.
“They don’t like light pollution. They like to look up in the sky. They like the desert feel,’’ Luna said.
Luna said that Transportation Director R.J Zeder has carefully drafted an ordinance to address the needs of radically different sections for the city.
The new system will provide a lot of flexibility – but won’t resemble the kind of citywide dark sky ordinances that places like Flagstaff and Sedona have adopted to reduce light pollution.
“You might call it a darker skies ordinance in some places, but it’s not a dark skies ordinance,’’ Zeder said. “Different parts of Mesa have different characteristics.’’
Vice Mayor Mark Freeman, who represents Lehi, agreed and Mayor John Giles also said he supports the proposal.
“Some people like the light and others do not,’’ Freeman said. “I like the ability to dim.’’
Zeder said the plan started as a necessary effort to replace sodium vapor lights, which have a somewhat yellowish hue because they are getting phased out by LED technology.
The next step was developing a master plan that leverages LED technology effectively.
“This is all about pedestrian and motorist safety,’’ Zeder said.
In the latest part of an extensive infrastructure-modernization campaign, Crews would change out 4,850 fixtures per year.
The level of lighting on most major roads would be reduced to 45 percent of maximum power and down to 25 percent late at night in less busy areas of northeast Mesa and Lehi.
In Lighting Zone One, Desert Uplands and Lehi, lights on arterial streets would be dimmed to 25 percent from 10 p.m. to 5 a.m., while in Lighting Zone Three, which covers much of the city, the lights would be dimmed to 45 percent on all streets from 11 p.m. to 5 a.m.
Mesa refers to its approach as “adaptive street lighting,’’ but also says that the pilot program was intended to use an illumination level “similar to the dark sky lighting levels of other municipalities in Arizona.’’
Flagstaff and Tucson, cities near major observatories, are among Arizona’s dark sky cities, as well as Sedona, Fountain Hills and Camp Verde.
LED lights are not only brighter than sodium vapor lights but can be dimmed with “smart nodes,’’ gadgets that has added $10 million to the overall cost of the program.
“The proposed ordinance will allow us to dim but not require us to dim,’’ Zeder said, noting that right now, “The bulk of our lights cannot be dimmed.’’
“I think we have struck the right balance where we feel we are comfortable cutting power and maintaining public safety,’’ Zeder said.
Chris Luginbuhl of Flagstaff, a retired astronomer with the U.S. Naval Observatory and dark skies advocate, said Mesa’s plan has components of a dark sky ordinance but is not comprehensive enough to qualify as one.
“This is a step in the right direction,’’ he said.
A member of Flagstaff’s Dark Skies Coalition, Luginbuhl said the dimming will help compensate for the brighter LED lights in northeast Mesa but that in areas with the 45 percent power, the light pollution will be slightly worse than the present sodium vapor lights cause.
“You don’t have to use the same amount of light all the time. That’s a step forward,’’ Luginbuhl said after reviewing Mesa’s plan.
He suggested the city take further steps to reduce additional light pollution from the LED lights by using amber-colored LED lights instead of white and installing shields on light fixtures that force light downward rather than upward.
Zeder noted that his staff fabricated and installed them along Ellsworth Road after some neighbors complained about brightness.
Luginbuhl said this approach should be required throughout the city.
“It’s a quality of life issue. You want to make it as dark as possible,’’ he said. “Use what you need. Don’t use more than you need.’’
Zeder said he agrees with Luginbuhl in some ways, but that it is too early say what color light the city will select. He said Mesa already is using a less intense LED light that is not as white as the maximum.
He said the shields were successful on Ellsworth Road, where the street lights are in the median and the devices blocked “spillover’’ into people’s houses and yards. He does not rule out using them elsewhere in Mesa.
“We are not trying to over-light our streets,’’ Zeder said. “We are going to watch and see how technology changes.’’
He said that changes in technology and costs make the conversion to LED streetlights much more appealing today than in the past. Still, the consultant’s master plan says it will take Mesa about nine years to recoup its savings from LED, while the lights themselves are expected to last for about 20 years.
“Many years of research have resulted in LED luminaires that cost the same or just slightly higher,” a consultant’s report states, adding:
“LED prices are continuing to fall, life is increasing, and they are constantly becoming more energy efficient.”