Street lights–what are the issues?

53d965b51120bby Barbara Clowers

There are many issues that most of us are unaware of regarding the street lights retrofit we are installing in Davis that goes beyond simply personal preference for a certain quality of light outside our homes.

To begin, we need to understand that while we may choose to light up the night the same as we choose to use fossil fuels, there are environmental consequences to that use. Just as we strive to limit the pollution from fossil fuels, we need to understand that light at night is a form of pollution and understand the consequences of that pollution which include:

-an increase in air pollution
-an increased risk for cancer in humans
-the (often unnecessary) use of energy and money
-an increase in glare that decreases safety
-an increase in current lighting levels that hampers our night vision
-a negative impact on animals
-a loss of the wonders of the night sky for everyone

Humans have an innate fear of the dark. We equate the dark with ignorance and the unknown. Culturally, light is a symbol of enlightenment, knowledge and security. We use light metaphors to describe understanding and the good; we think of lighting as a good thing but all good things taken to extremes have their dark side.

Street lighting became widespread in this country in the 1930’s when utility companies had excess energy at night and they needed a night time base load for their thermal power plants. Street lighting was the perfect solution. Street lights were made inefficient, so they used more energy. The light bulbs were designed to burn out to maintain an income stream for the manufacturers, suppliers and salesmen. Cities were charged a flat fee so they had no incentive to conserve. We stopped having excess energy to sell at night in the 70’s but by then municipalities were spending a large portion of their energy budgets on street lighting and it had become the norm and was considered (still is considered) a necessity when in fact it is the forgotten remnant of an obsolete energy practice.

In 2012 in the United States, 19% of our electric use is for lighting and 16% is used for outdoor lighting for a total cost of 11.6 billion dollars. Experts estimate 30% of that is wasted light; lighting where it is not needed, when it is not needed or direct uplight that illuminates the heavens. This wasted light costs us about 3.5 billion dollars every year. As Everett Dirksen said, “A billion here a billion there, and pretty soon you’re talking real money.”

The wasted energy amounts to 30 million barrels of oil and 8.2 million tons of coal and releases 14.1 million tons of CO2 into the air. In an effort to reduce the money spent and the CO2 produced, cities across the world are using these two criteria to retrofit their streetlights with LED lights. Unfortunately, this is a two dimensional solution to a multi-dimensional problem.

In Davis, these were two of the three goals of our retrofit. The third was to replace burned out fixtures. An energy audit was done by Siemens, the contractor who is also doing a complete energy audit of city owned buildings. To the best of my knowledge, that audit of streetlights was an inventory of the number of fixtures we have, the type and the absence or presence of numbering on each fixture and who owns the fixture, the city or PGE. What was not done was an assessment of where we have light, where we need light, when we need light, what kind of light is needed and HOW MUCH LIGHT IS NEEDED.

How does light at night increase air pollution other than by burning fossil fuels to power them? During night time hours, a form of nitrogen oxide, the nitrate radical NO3, is formed which breaks down chemicals that would otherwise form smog and ozone. This process is destroyed by sunlight and is inhibited by light at night. Night time cleansing is slowed 7% by the sky glow above cities and can increase the chemicals for ozone pollution the next day by up to 5%. You can read more about it here:

Since when does artificial light cause cancer? Well, it may not cause cancer but it increases the risk of breast cancer, ovarian cancer, prostate cancer and colon cancer. There is an extensive body of research on breast cancer based on the theory that nocturnal disruption of circadian rhythms reduces the production of melatonin. Night shift work increases the risk, blind women are at lower risk while partly sighted are at the same risk as other women, and according to the National Institute for Health, “nighttime light level co-distributes with breast cancer incidence worldwide.” These studies have resulted in the International Agency for Research on Cancer a part of the World Health Organization classifying shift work as a probable human carcinogen. The American Cancer Society includes “night work” as a cancer risk factor. The American Medical Association unanimously passed resolution 516 supporting light pollution control efforts and glare reduction efforts in 2009. While no one is saying blue rich white light (LEDs in their current incarnation) causes cancer, there is credible research that shows exposure to 6,500 CCT (ours are 4000) streetlight for one hour is expected to show measurable effects on human melatonin production. Here is a link to further information on medical research into light at night:

There are other health problems associated with exposure to light at night including depression, obesity, diabetes and heart disease. We voluntarily expose ourselves to light at night in many forms–TV screens, computers and cell phones as well as our indoor lighting. If it concerns us, we can make lifestyle choices to minimize our exposure inside our homes UNLESS WE ARE CONSTANTLY BATHED IN LIGHT TRESPASS FROM CITY STREET LIGHTS. As a city, I believe we should make every effort to keep our lights shining where we want them (on the streets and sidewalks) and not in our homes. In case you think low levels of light are unlikely to cause problems, think again. Recent studies on mice show that chronic exposure to a dim blue/white light at night disrupts the circadian rhythms, suppresses melatonin production and increases inflammation. Turn those night lights off!

Humans have evolved with the ability to see at night in low light. The light of the full moon shines on the earth at about 1/100 foot-candles. The standard for the lowest level of light (residential) in Davis is .6 foot-candles for each of our neighborhood light fixtures. This is about 60 times brighter than a full moon emanating from every light fixture! I think a reduction in this standard is in order.

The human eye is adapted to the dark. When the levels of light are lower, our eyes dilate, we lose the ability to see color but we can see graduations of light and dark. A higher intensity of light creates a sharp contrast with shadows, making the shadows appear impenetrable, whereas with a lower level of light the shadow of a building, a tree or a bush has more definition–our ability to distinguish objects actually improves. We have a tendency to increase the levels of light to “see better” even though visual functions at night are impaired by that increase. The shadows become a black foreboding unknown shape so we add more light and make the contrast even deeper and more difficult to distinguish shapes. One of the goals of most outdoor lighting is uniformity but research shows that we see better with overlapping ovals of light which help us to judge distance and see movement.

Over 30 percent of vertebrates and 60 percent of invertebrates are nocturnal and many of the rest are crepuscular, that is, active at dawn and dusk. All are potentially impacted by our use of artificial light. Up until the advent of LED lighting, outdoor lighting has been in the warmer color ranges and we know that even those lights have negative effects on animals such as sea turtles, but the blue rich white lights are much more harmful. Every light contributes to altering ancient patterns of mating, migration, feeding, and pollination. We cannot modify light half the time without consequences.

There are special concerns related to the color temperature of our LED lights. LED lights are promoted because they are closer to the color range of sunlight than most (but not all) of the lights they are replacing, making it possible to see some color at night, however there are specific problems with this kind of light at night that aren’t found with lights that are shifted toward the yellow and red end of the spectrum.

LED lights can be made in any color but they are most energy efficient in the Blue-Rich White Light (BRWL) range. While the manufacturer of our lights tells us to ask about warmer LED lights, the answer is they do not produce them lower than 4000K. Sure, we can get them, if we want to pay for a special production run (and to the best of my knowledge, they have never fulfilled such a request, so we can ask but it really isn’t an option).

According to the International Dark Sky Association (IDA), “..the stronger blue emission produced by white light sources, such as LEDs, has been shown to have increased negative effects on astronomy and sky glow, and has a greater impact on animal behavior and circadian rhythms than other types of lights.”

Since we are putting these lights in our communities to save money and reduce CO2, it is prudent to at least be aware of the negative consequences.

The IDA information brochure continues, “Under typical outdoor environments illuminated by artificial lighting, our eyes have a mixed visual response with a complex and only partly understood combination of light-adapted and dark-adapted vision. This means the benefits BRWL sources in the real world are usually less, often much less, than predicted by the simple correction factors that have been proposed to explain response under laboratory conditions. This means much of the benefit of BRWL sources is only realized when illumination is much fainter than commonly encountered in artificially illuminated outdoor environments and when the distribution of light is tailored to take advantage of the eye’s response. Research…indicates our understanding of the effects of light at night, lags behind the development and use of new lighting technologies.” Therein lies the problem with simply switching out old fixtures for new LEDs with equivalent lumens. We are not comparing apples to apples.

In addition, glare is a problem with LED lights as we can clearly see here in Davis. The fixtures we have installed are currently IDA approved, however revisions to the IDA guidelines, are expected to be approved within two months, and these fixtures will not meet the new standards. Studies from as far back as 1995 show that BRWL causes more glare. Later studies confirm the wavelength of 420 nm to be most closely linked with discomfort glare. Any light source with the spectral output below 500 nm will increase the perception of glare, particularly for older people. The human eye has not adapted over time to deal with nighttime glare since it does not exist in natural nighttime conditions. It takes our eyes 20 to 30 minutes to fully adapt to darkness yet it takes only 5 minutes to go from complete darkness to bright light.

A note on measurements: the visible spectrum runs from about 740 nanometers (nm) to about 380 nm. Color Rendering Index (CRI) uses a scale from zero to 100 and measures light quality in relation to the eye’s ability to see colors correctly–80 to 100 is desirable; daylight is 100. Color Temperature (CT) measures light from cool to warm in units of degrees Kelvin (K).

The LED Street Light Research Project, published in September 2011, discusses glare and LEDs,
“…interviews with manufacturers and municipal agencies in cities with LED replacement projects indicate that the emphasis is being placed almost entirely on energy savings, to the exclusion of visual quality issues. The substantial glare caused by LEDs is not typically included as a measurable criteria in evaluation processes, and when it is, the tools of measurement are inadequate. As a result, glare persists as an issue. It is very difficult to use common light measuring tools and to measure LED lighting accurately especially luminance (brightness). As a result, the performance quality of LEDs is often over stated.”

LED lights produce 15% to 20% more sky glow than the lamps they replace because of the eye’s sensitivity to blue light at lower levels. While we replace some of the dropped lens HPS lights with full cut off lights we are also replacing many perfectly acceptable full cut off HPS lights with these LED lights that create more sky glow than those they replaced. I am an unfortunate home owner with 6 lights that shine in my bedroom window. In 2007, 4 of those lights were replaced with HPS full cut off fixtures that made a tremendous difference in our lives. On May 26, those 7-year-old fixtures were trashed and replaced with LEDs resulting in light trespass worse than the original fixtures. We have gone backwards with this well-intentioned but poorly researched retrofit.

I have been asked why we don’t just close our bedroom windows and use our black out curtains so we aren’t bothered by the street lights. The city is installing these lights to save money and reduce CO2. If every person bothered by these street lights in Davis closes their windows blocking out the cooling delta breezes and turns on their air conditioners, are we really saving money and reducing CO2? Or are we shifting the cost from the city to the residents? And don’t we pay for those lights with our taxes? The other reason why expecting me to close my windows is unreasonable, is unwanted light is like unwanted noise (or music) or second hand smoke that prevents me from the use and enjoyment of my property. I don’t and am not allowed to blast sound into my neighbor’s homes disturbing them. I do not see how unwanted light differs from unwanted sound.

What is the status of our retrofit program? Seventy five percent of the new cobra head fixtures have been installed. One hundred percent of the non-residential areas have been changed out and 50 percent (600 fixtures) remain to be installed in residential areas. The city staff has released its recommendations to the city council. Unless something happens to convince the city council otherwise, they are likely to act on the staff recommendations to just finish the project.

In their report they note there have been 49 complaints, 12 neutral comments and 13 comments in support of the new lights. Some tests were done to see if dimming the lights helped; there was a perception of a slight difference in glare, color and light levels when the lights were dimmed 25%. When shields were installed the California Lighting Technology Center (CLTC) staff felt they did mitigate light spill to the sides but glare and light spill across the street did not change. At least 50% of the residential lights will produce glare and light spill to the front, that is to say, across the street and there are no shields to reduce light spill from the front of the fixture.

“Glare reducing lenses and lower color temperature fixtures are not readily available,” the city staff states. “Bicycle, pedestrian, and general safety is assumed to improve under all options due primarily to more consistent lighting across the community.” I believe this last statement to be an OPINION based entirely on unsubstantiated, undefined, untested assumptions and totally without merit. My contacts in the bicycle community say they have not been contacted nor asked for their input on the new lights. The assumption that brighter whiter lighting makes a pedestrian who experiences glare each time he glances up and sees the next light bomb is not based on any study done anywhere, ever. I challenge anyone to find any credible evidence that LED lights improve pedestrian safety. I make the same challenge for bicycle safety. What you will find are statements that reflect the increased FEELING of safety when there is increased lighting.

The city staff recommends negotiating with Siemens to provide material and labor for the installation of up to 400 shields one year from the date of the last retrofit. The alleged reason for the delay of one year in installing shields is to give residents the opportunity to live with the fixtures in all seasons. It seems obvious that anyone who doesn’t like them in the summer when the trees have leaves that block some of the light and the lights come on relatively late in the evening are not going to like them any better when the trees are bare and they come on at 5 pm. The unstated reason for the delay is that installation of shields is not recommended until municipalities receive their rebate from PGE; this can take take up to a year. But it is mostly because the shields can alter the performance of the fixture and the rebate ($185,000 in our case) is contingent on certification of lamps at a certain performance level.

What are our options?

-recommend the city return these fixtures, at least the ones in residential areas
-recommend the replacements be a warmer temperature and not produce glare
-require that any LED light source not be visible to drivers, bicyclists, or pedestrians unless they are
directly under the fixture.
-recommend an audit that asks the questions, where, when and how much light do we need
-recommend the lights be dimmed by 50 percent
-demand shielding be put in place immediately or replace lights where there are complaints
-request that we save money and reduce CO2 by putting a curfew on residential lights

A curfew begins at an agreed upon time and must stay on that schedule. While the city staff says there is no cost savings if the lights are turned off that is a half truth. In fact, we do pay a fixed tariff for each light depending on the wattage and we pay whether or not the lamp is functional. However, if we decide to turn a light fixture off at 11 pm and on at 5 am we get 12 half hour reductions on the tariff for that lamp. For our residential 27 Watt lamps, the tariff is $1.113. The half hour credit is $.051. Credit for 12 half hours reduces the tariff to $.501. We just cut the electricity cost by more than 50 percent .

In order to qualify for the half hour credit, the fixture must be turned off every night for the same number of hours. This would require we install an inexpensive timer for every fixture with a curfew. Fixtures not eligible for curfew would be those at intersections and crosswalks.

Footnote on saving money. LED fixtures are not inexpensive, in fact the upfront cost is higher than other types of fixtures. Based on the number of fixtures in the Siemens bid, I believe these lamps cost us about $390 each. We paid for 50 replacement fixtures. The replacements are a very poor investment. The cost of LED lighting is plummeting like the cost of computer chips since the 1980’s. Cree recently came out with an LED fixture they are selling for $99! This $99 fixture has the same warranty (15 years) as the ones we bought and it has two levels inside each housing so they can be mounted horizontally. Ours have no levels and a quick check around town will confirm that many of them are not mounted horizontally which makes the glare from them even worse.

Finally, light pollution is only expected to get worse, worldwide. Annually, the increase in lighting at night grows between 3% and 20% with an average of 6% per year with no limits to growth. Currently, 99 percent of Americans never routinely see a true dark sky. And by 2025, experts say, Americans will be lucky to have two or three places left inside their borders where one even exists. In Davis, I could see about 250 stars on most nights and sometimes more during a new moon. After the new lights were installed on May 26th, I can see about half that.

Economists have begun using satellite pictures of the earth at night, studying the intensity of lighting to measure economic growth. Every time we add another streetlight (think The Cannery) or increase the intensity of blue lights (our 2,600 new streetlights) we increase the sky glow over Davis, diminishing the number of stars we can see. Below is a picture of the United States at night from the late 50’s with a projection of the night sky in 2025 .

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  1. Tia Will

    Thanks for the article Barbara.

    Since having this issue brought to my attention, I did some homework and can confirm on the basis of limited studies of women shift workers from 2012 and a slightly earlier meta analysis that women who work night ( or alternating day to night shifts) do have a modest increase in the risk of breast cancer. They do not however appear to have an increased risk of death from breast cancer. The fact that women with alternating shifts have the same risks as those that are solely night shift workers would appear to support the melatonin hypothesis.

    It is important to consider what we do not know as well as what we do. We do not know what amount of light for what amount of time is sufficient to cause this effect. For example, if 8 hours of exposure is needed at a high level of exposure ( such as would be the case for flight attendants, factory employees or nurses who were the primary subjects in these studies) then lighting as used in the city would not appear to pose a significant risk. However, if the amount and duration of exposure associated with increased cancer risk was much smaller, we might be putting the population at risk.

    At this point in time, what would appear prudent to me, considering the breast cancer issue only, is to minimize the amount of light especially in residential areas. This will in and of itself have some downside. Despite the studies that demonstrate better nocturnal vision with dimmer more evenly distributed light, I can personally attest from several “near misses” that some of us have night vision that is significantly improved by more light. ( I live in a relatively dark neighborhood and have nearly gone down on uneven sidewalks at night). In this regard, I may have missed it, but I have not heard mention made of the possibility of motion sensors on lights in residential neighborhoods. No need for light late when no one is out, but definite need for we older folks who are walking home after a late movie or concert. Has this been considered ?

    1. DavisBurns

      Tia, the more you look for studies the more you find about blue blight and the increased rate of cancerand other effects on health. While the risk is small, don’t we make a lot of lifestyle changes to reduce the risk of cancer?

      We can still have street light but we need to revisit the city ordinance that specifies height, spacing and foot candles. That would take a big push from residents. In fact I think the council will be inclined to follow staff suggestions.

    2. DavisBurns

      Tia, motion sensors were discussed at one of the city council meetings. One of the members (Brett or Wolk?) said the problem with them was if you want to step outside and see stars, they are the wrong option. Because these are not smart lights, a motion sensor, like a timer would be an add on. Motion sensors are not included in any of the seven options discussed in the city staff report of June 24, 2014. Motion sensors are used extensively on campus.

    3. Alan Miller

      T.W., there is a row of lights on campus on what would be an extension of Third Street as you approach the Rec Hall, next to the parking lot, where there is a row of LED lights with light sensors that brighten as people pass under them. I found them extremely annoying. They come on after you pass under them on a bike, so they do no good for seeing ahead. Perhaps if they were all dim and then all came on at once when someone approached a block of them, it might make some sense. But then there would be this weird dynamic where everytime a person entered a block, all the lights would come on and it would get bright on the block. That’s a bit creepy to me.

  2. Mr. Toad

    My usual first response to this light issue was a yawn and a dismissive reflection on how someone will complain about everything in Davis but then my daughter spoke up. She told me she didn’t like the new lights because they were too bright and she couldn’t see the stars at night. This was totally unprompted and shocked me. It also is true. Until the new lights were installed we often looked up as we left the house or came home after dark. I would show her Orion’s Belt, The Big Dipper, Little Dipper and Polaris the North Star. Cassiopeia or The Seven Sisters (AKA Subaru in Japan you can see these stars on the cars front medallion), Leo, Vega, Regulus and Sirius. We would look at the moon and the planets trying to figure out which planet without a telescope. Now this game is over, sacrificed to public safety. I would like my daughter to be able to see the stars without seeking them out. I hope there are things the city and Siemens can do to direct the light where it is needed at keep it from where it is not. We live on a major bike path but reducing power should save money and reduce CO2 without adversely impacting road safety because the lights are brighter than what it seems is needed. Also shading to keep the light where it is needed seems like a good idea to try as a start.

    It wasn’t that long ago that we enacted an ordinance about pilfering from recycling containers with not that many more complaints than the almost instantaneous 49 generated by the partial installation of these new lights. Funny how when the city wants to do something the complaints are a big problem but when the doesn’t want to do something its not that many. I guess my complaint makes 50.

  3. DavisBurns

    For your complaint to count, you need to email msears@cityof Davis .org. Thanks for your support. I’m so glad your daughter likes to see the stars. My husband took a couple of telescopes to slide hill park for a Girl Scout camp. The one girl most excited about astronomy was from Roseville where she can see the Milky Way from her back yard. Our grandchildren may never see even the Big Dipper from Davis. Places with dark skies are now tourist destinations.

    1. Matt Williams

      DB, if you want to see the stars, all you have to do is drive to Harper Junior High School or the south side of Montgomery Boulevard or in El Macero or on the Wildhorse Golf Course. There the light spacing is sufficient to provide dark skies. It is likely that all of our schools in town have dark skies with the exception of the Senior High School.

      1. darelldd

        Matt – it turns out that you don’t need to drive to any of these locations. Many could walk or ride, and reduce the OTHER cancer-causing pollution that we don’t seem to think much about while light pollution takes the spotlight.

        1. DavisBurns

          Darell, would you care to comment on the new lights from a cyclist’s perspective? Do you notice glare or darker shadows for the green waste to hide in?

          1. darelldd

            This issue is a tough one for me to comment on, though I have written an extensive note to our council members, and have discussed this with the team that is currently tasked with “fixing” the issue. Most of the complaints I have heard from the public are subjective (too bright, too intense, too glaring) and I have trouble getting over the objective part of the process. The human perception of light is a tricky one, and when the complaints are not objective nor quantitative, the fix can be quite difficult to find. The human eye is more sensitive to light in the blue-green range, than in the orange-red range. We are not concerned with the *amount* of light here – we are concerned with how bright it *appears* to the human eye. And of course we’re all different. As an example, I can’t stand the sickly yellow and horrible CRI of our old street lights. It makes me physically uncomfortable to be in that light, and I avoid it. Others find my LED lighting too “sterile” and prefer yellow incandescent lighting.

            I have been designing and building with LEDs for over 12 years. My entire house, my cars, my bikes are all lit with LED – most of them purpose-built for the application. My expertise and experience here isn’t in navigating around piles of green waste by the light of cobra heads – it is (maybe surprisingly) in LED lighting. And maybe more importantly, in designing the proper light (color temp, lumens, CRI, diffusion angle) for the application.

            The short answer is: No, I don’t find that the new LED lights make it harder to avoid green waste piles in the street as compared to the old lights. The lights and shadows are not the problem in that situation.

          2. Matt Williams

            darell, I’ve often wondered whether the “brightness” problem is one of the foot-candles of the light or the wavelength of the light. What are everyone’s thoughts on that? Are there LEDs that produce light in different wavelengths?

          3. darelldd

            Matt – Foot-candles (or intensity) is part of the equation. Lumens is another. Angle of diffusion yet a third. And finally there is color temperature. Oh, and shielding, and distance. These values are intermingled. We can’t fix the problem by adjusting just one or another. The entire package needs to be considered – and that’s what we seem to have missed.

            Understand that LEDs are natively monochromatic. They naturally produce a single wavelength. We don’t have “white” LEDs. We fake white light today by using (typically) a blue LED that’s coated with a yellow-ish phosphor. White is not a wavelength – ideally it is the combination of *all* wavelengths of visible light. Realistically, it is whatever appears white to the human eye.

            So the easy answer:
            Yes, it is the brightness, it is the intensity, and it is the wavelength that needs to be considered and adjusted to make everybody happy. Color temperature is a HUGE part of this conversation. And as much as I like higher color temps personally, I can’t imagine why we’d choose anything over about 3500k to start with when converting to LED from our astonishingly low Kelvin exiting lights.

  4. Mr. Toad

    Or go into my back yard but something was lost with these new lights. They are too bright and cast their light too broadly. The city should first try to see what adjustments can be made.

  5. Alan Miller

    The article is long and covers a lot of issues, some of which are substantiated and I agree with, while others such as the cancer issue are more extrapolations of other studies to a probably not provable connection. The problem with this approach of throwing mud at the wall is that it may confuse the issue and allow the “pro-BRWL” people to attack non-provable items while ignoring the substantial ones.

    I had commented that being in a bright area it is harder to see into the dark. The next week the staff report simply dismissed this and said it was not a problem. The approach being used is not working. Simply sending an email to the City staff responsible for a report they have already decided upon will not yield a dark sky. Also, similar to the “two lanes mean twice as many cars can get to downtown” initial thinking on 5th Street, people are equating “more light means we are more safe”. You did a pretty good job arguing that, but the arguments need to be concise and agreed upon by many.

    About 7-8 years ago I remember the City of Davis was proud to sponsor Dark Sky programs such as fixtures that focused light downward-only. The City itself made a big deal out of this, our being a “Dark Sky City”. Does any have any of these articles handy to bring to current City council? Was there not at the time an organized group of Dark Sky citizens? Does this group still exist, or does anyone have an list of members or participants?

    This issue is about to be decided, and it is currently going the way of a Davis with harsh evening light. Having all the arguments is not how this issue is won. We must be: 1) concise 2) vigilant 3) immediate 4) reasonable 5) organized. First of all, we need to focus on a few main points. They don’t have to be scientifically proven. It is OK to say we don’t like the lights. It is important now to talk directly with City Councilmembers and tell them your thoughts on this.

    The new lights are too bright, change the ambiance of our homes and neighborhoods and have a harsh glare. The difficulty of the human eye to adjust is very real. On a bicycle in neighborhoods where the lights are spaced further this is quite real. One passes under one and then you go into a dark zone quickly and it is harder to see. As well, the harsh glare when passing directly under these lights, even at my age, produces a light-dispersion similar to that through a car windshield at night, further hampering vision. I have found wearing a baseball cap when I ride at night on major streets helps, but that just shows how ridiculous the glare is.

    I am not asking for dark streets. Street lights are helpful and necessary, and most important is that we get all the burned out lights replaced, NOW. This should not be hard with all the removed lights available. Davis needs to really stop, take a pause on this issue, and consider the effects of so much bright white night light, on safety, Dark Sky (sky viewability) and ambiance. I am asking that we have pleasantly lit residential streets. As was pointed out in the article, LED prices continue to plumet. As well, the availability of new LEDs is growing all the time. There must be cities that have requested a more yellow-spectrum light that we could team up with to come up with lights that are a more pleasant light frequency, bright enough for safety, not glaring, and don’t light up the sky so much. As has been said, the shields and the lowering of the power level are not reducing the glare.

    This is something that can be compromised on. But if we finish now, the City will look a lot like Oakland, where this Cobra fixtures bath the low-land neighborhoods in a harsh, bluish-white sterile bright glow. My neighborhood is permanently scarred by the silver, industrial looking railroad fence by day, I value greatly the mellow glow of the pale yellow sodium bulb by night. That light frequency is completely replicable as an LED, just as I had to wait a few years before Philips produced a perfect replica of the incandescent bulb light: I now have my house completely retrofitted with those LEDs. The City should do the same with our street lights.

    1. DavisBurns

      Alan, I agree we need to be brief, concise and organized however there are so many different issues I want to put them out there and see where people’s passions lie.

      Tia is interested in the breast cancer aspect. The other health problems associated with suppressed melatonin secretion, are not unsubstantiated. Since 1998 there have been many studies that look at health effects and there is ongoing research. Just don’t dismiss health issues out of hand. They are significant. Deborah Burnett of Benya Burnett Consultancy speaks worldwide on the health effects of blue light at night. She has offered her services to the city as has her husband, James Benya whose field of expertise is lighting and is on the board of directors of IDA.

      I have a copy of the Dark Sky Ordinance which was passed in 1998, sponsored by Julie Partansky. You can find it at It is a part of the Davis Municipal Code chapter 35 Streets and Sidewalks. I googled key words and got the whole thing online, then copied and pasted the relevant parts.

      Julie had a friend who enjoyed astronomy and he was the inspiration for her to propose the Dark Sky Ordinance. Unfortunately, they are both deceased now. There is a chapter of the International Dark Sky Association in Sacramento. Jack Sales was the president when Julie was doing this and had a hand in drafting the ordinance. There is a couple who have public meetings about astronomy at Explorit occasionally. My husband and two or three others get called on every year to take telescopes to 3-4 events during the summer to let kids have a glimpse of the stars. I know of 3 IDA members here in Davis.

      “On a bicycle in neighborhoods where the lights are spaced further this is quite real. One passes under one and then you go into a dark zone quickly and it is harder to see.”

      We agree completely. Dimmer lights closer together and closer to the ground are better for cyclists and pedestrians. Cyclists are required to provide their own lights so I don’t know why we think we have to provide lights for them. At lease one cyclist with extensive experience commuting in the dark and riding in events that extend past midnight, says he is least visible at night with all his numerous lights on, at a brightly lit intersection. He says when he is on a dark road he can be seen from far away but when he rides in town he is much less visible.

      I don’t think pedestrians SHOULD have to carry a flashlight but I do since the new lights were put in. My eyes contract from the intense lights and I can’t see anything in the shadows.

      I am not advocating dark streets either. The community needs to understand the issues and I hope to foster discussion about what we want and can agree on. I expect that I will not get all I want but if we can begin to incorporated light pollution into our planning and try to limit the increase in the use of lights, I will feel successful.

      Santa Rosa embarked on an interesting street light reduction program that has been successful. San Diego has installed warmer colored induction lights. The change to LEDs is driving the lighting market with sales projected to reach 1.9 billion dollars in 2017. LEDs are being pushed hard and that is what most cities are choosing. It is possible to have higher standards for color temperature and glare. Right now almost all cities have criteria just like ours. Until cities start including light pollution, glare, visual comfort, color temperature in the goals of the projects, manufacturers have little incentive to improve their offerings.

      I think our current lights are already outdated, inferior and overpriced.

    2. DavisBurns

      “I had commented that being in a bright area it is harder to see into the dark. The next week the staff report simply dismissed this and said it was not a problem”

      We must have said much the same thing. The Dave Ryan wrote in the Davis Enterprise, “Whether the council picks dimmed or shielded lights, city officials believe safety is not an issue with the new LED lights, despite past comments from the public who are worried about criminals more easily hiding in the shadows.”

      I thought he was referring to a statement I made about defining safety. I wanted to know if “improves safety” means “reduces crime” or if it means “safer for people walking”. I said deeper shadows makes it easier for criminals to hide in the dark. For the record, I am not concerned with criminals hiding in the dark, but it is true that increasing the brightness of the lights, especially in the blue end of the color spectrum, causes human eyes to contract making it more difficult to see in the dark. The shadows APPEAR darker because your eye responds to increased light very fast but takes 20 to 30 minutes to dilate/adapt to the dark. Consequently, when you look at one of these glare bombs we have installed, you can see much less outside of the circle of light from the streetlight and the shadows APPEAR darker and if someone or something is in the shadow, it becomes very difficult to see.

    3. DavisBurns

      “About 7-8 years ago I remember the City of Davis was proud to sponsor Dark Sky programs such as fixtures that focused light downward-only. The City itself made a big deal out of this, our being a “Dark Sky City”. Does any have any of these articles handy to bring to current City council? Was there not at the time an organized group of Dark Sky citizens? Does this group still exist, or does anyone have an list of members or participants?”

      Alan, you may be thinking of 2009 which was the International Year of Astronomy and also the year Julie died. I will be happy to look for the articles about Julie and bring them to the city council meeting. There were many articles in national magazines about dark sky ordinances at that time and the general public had more exposure to the problem of light pollution than any other time before or since. I recently read an interview with USA Today from 1999

      which said:

      Partansky went so far as trying to get the city to turn the lights off after midnight, especially along the “greenbelt” bike and hiking paths, but the City Council balked.

      “They were against it for safety reasons, but there are areas where they do go off at 10,” she says.

      Safety issues come up often when dark-sky ordinances are discussed, although a landmark Justice Department study concluded years ago that street lighting has no effect on crime.

      “There’s no evidence that supports crime goes up when the lights go off,” Partansky says. “I think it’s people’s primal fear of the dark that supports those theories. You know, the bad guys have to see, too!”

      “It’s a natural concern,” says Robert Brucato, assistant director of the California Institute of Technology’s Palomar Observatory, near San Diego, “but if you look at the numbers, it’s just not there.”

    4. DavisBurns

      I too have remodeled my house and I have primarily LED lights installed. Some of them are whiter than I like but I am not just opposed to LED lighting. I can turn my lights off. I can’t turn off the streetlights which are on even when no one is around, the houses are all dark and everyone is in bed.

  6. DavisBurns

    The city has had Michael Sminovitch from the California Lighting Technology Center (CLTC) conduct experiments with dimmed light. Dimming them by 25% made a “slight” difference in perception of brightness but did nothing for the problems of glare. I believe the city didn’t ask CLTC to participate until after people stared to complain. In Sminovitich’s comments to the city council he ‘commended the city on embarking on this retrofit, the center looks forward to working with Davis and Siemens to develop a world class specification for street lighting’ but the city has not actually expressed any interest in developing any such standard. He goes on the say such a standard would address the glare and color temperatures issues inherent in LEDs. He says the city is. “Future proofing “itself by installing smart lighting so we will be able to take advantage of the rapidly changing developments.’ We are NOT future proofing anything. This system doesn’t come with the ability to control the fixtures remotely by wifi or other transmission technology. We bought a stupid system not a smart one. That is why I suggest we do use time tested reliable timers for lights we want to turn off when everyone is in bed.

    I believe davis isn’t in the position to spend money on a smart system. I think it’s early days for wireless control of the street lights. They are promoted as having the capability to monitor the lights, know when on is malfunctioning , dim or brighten them asthenosphere streetlight nearest a call to. 911 would be made brighter or to flash. They also talk about emergency exit routes being lit up brighter. My husband says just wait till someone hacks into that system. The industry is still working on standards.

    Meanwhile, Siemens says, “We are technology agnostic and vendor neutral….we are ready to be nimble and provide the solution best for the city” so they should be happy to use a different fixture.

    1. DavisBurns

      Clem, there are some great things that can be done with LEDs like tiny organic leds that decorate trees but probably we will just replace streetlights.

      Replacing the 505 acorn light fixtures will cost more than replacing all 2600 cobra head lights. Those are not yet scheduled to be replaced but it would be great if we could do something creative to replace those guys. Generally, they are considered ‘historic’ and most cities keep them even though they are expensive and its not really possible to make them shine down. They have the potential to be major glare bombs if they just put LED lights in them.

    1. darelldd

      And do you have some pressing third-world problems that our city council should be solving? Having first-world problems is a requirement for being a first world nation, as far as I understand the term. If we were dealing with third-world problems (oh, like tossing our refuse into the street), we wouldn’t be first world, would we? If first-world problems bore you, there are many, many places you could be living where there are no first-world problems to deal with. And cost of living is pretty cheap! So… I guess I miss your point.

      1. Offering Balance

        Labeling something as a first world problem points out how truly trivial the issue is, especially compared to other issues the city and surrounding areas face. Then again Davis is the town that builds frog bridges so I guess light pollution is par for the course.

        1. Mr. Toad

          Maybe you are dismissive of my concern but I happen to like seeing the sky at night and think that the lament of a child not being able to see the stars is worthy of trying to seek adjustments..

          1. Matt Williams

            Sounds like an opportunity to change the evening routine and get some exercise walking or riding to a viewing spot. Good for the soul and good for the body.

          2. Mr. Toad

            You keep thinking the solution is moving away from the lights but that is not the problem the problem is the lights being moved into my space.

          3. Matt Williams

            That is a fair assessment Toad, but the lights are not the only thing that is being moved into your space. Improved public safety for you and your family and your neighbors is also being moved into your space. Are you saying that you do not value that increased public safety?

        2. Tia Will

          Offering Balance

          I was also of the opinion that this was a trivial issue until I spoke with a personal friend who was I now believe rightfully upset about the issue. Her daughter’s bedroom was directly illuminated by one of these very bright lights. Even with shades drawn there was enough light that she could not sleep and was making do with a sleeping bag in their family room. While this may be trivial in the sense of issues facing the community as a whole, for the directly affected individual it may be anything but trivial.

          1. Matt Williams

            Tia, when the radio tower debate was in full flower a bit over a year ago, the topic of light shielding was actively discussed. It sounds like the light fixture adjacent to your friend’s home would benefit from some shielding so that the light is directed toward the public spaces, but not toward your friend’s private property.

            I did a quick search on the internet and ran into an article about the implementation of LED streetlights in Duluth MN which said, “Our city engineers deserve high marks for adhering to good lighting standards by packaging the new lights in shielded housings with minimal light spill upwards and to the sides. Light in those directions not only creates unwanted glare but seriously brightens the night sky, robbing many of the joys of stargazing.”

            One of the other interesting discoveries is that the LED lighting industry is already coming out with “Dark Sky Compliant” lighting fixtures. Another is that “natural color” LED lighting is available. If I understand what I have read, it is not as energy efficient as the high-efficiency LED lights that emit the much bluer light, but that relative inefficiency is probably still significantly more efficient than sodium vapor lights.

  7. Tia Will

    Another question for those who know more than I about this ( everyone) is there any precedent for light that operate like cross walk signals. You would only push the activating button when you needed the light on a dark strip of sidewalk ?

  8. DavisBurns

    Tia, what I have seen pretty consistently, is that when cities reduce lighting either by curfew or by turning some lights off permanently, lights remain on at crosswalks and intersections with traffic lights. Since I see that option consistently, there are probably safety reasons they leave them on. I don’t see why you couldn’t push a button to turn the light on the same as you push a button to get a traffic light to change. If we wanted to do something innovative, we could have lights embedded in the crosswalk.

  9. DavisBurns

    ” Street lights are helpful and necessary, and most important is that we get all the burned out lights replaced, NOW.”

    Alan, to the best of my knowledge, the burned out lights were the first one to be replaced. If you know of burned out streetlight (that you want to work) there is a place on the city’s website where you can report it. Pretty sure its in the public works section. Lucas was trying to get them replaced when he was first elected but he was told to be patient as they would be done when the retrofit began.

    1. DavisBurns

      Opps! The Davis Enterprise reports that when the retrofit program was put on hold, there were burned out lights that those lights would not be replace.

      I was under the impression that the burned out lights were replace FIRST in the retrofit but maybe not…

  10. DavisBurns

    “One of the other interesting discoveries is that the LED lighting industry is already coming out with “Dark Sky Compliant” lighting fixtures. Another is that “natural color” LED lighting is available. If I understand what I have read, it is not as energy efficient as the high-efficiency LED lights that emit the much bluer light, but that relative inefficiency is probably still significantly more efficient than sodium vapor lights.”

    The new LED lights we have installed ARE dark sky compliant. I called the IDA and asked about this fixture by it’s product number. It shines no light upward, it has a glare rating of one and a backlighting rating of one. While this seems like a good thing, the IDA will be changing it’s requirements in the very near future in response to the glare and color temperature issues that are particular to LEDs.

    Studies are showing that light that shines to the side (65 to 90 degrees) scatters light creating sky glow and glare more than previously understood. Glare with LED streetlights is a big problem as is the fact that it is light in the blue/white end of the color spectrum.

    1. darelldd

      > light in the blue/white end of the color spectrum. <

      Blue is certainly part of the color spectrum, but there is no white in the spectrum. By containing ALL of the colors of the visible spectrum, white light is colorless.

      1. DavisBurns

        You are correct. I used that description because most people see the light as “white” and not blue. Because it is on the blue end of the color spectrum, we perceive it as “white” like daylight. Most people would not characterize our new streetlights as blue and it appears more white as compared to the yellow lights that were replaced.

  11. DavisBurns

    “Another is that “natural color” LED lighting is available.”

    It is possible to make LEDs any color. The BRWL is the most energy efficient. As far as the fixtures Davis has installed, they have never had a production run of warmer colors (we could order it but if they were willing to produce 2 or 3 thousand, the cost would be very high. They do not make a lens cover that would have a positive effect on the brightness and color of the light. There are back and side shields but no front shield exists so if the light is coming from a fixture across the street from your property, you are out of luck. Perhaps we can have shields specially manufactured but it seems backwards to buy a brand new product and then have to modify it to make it acceptable to the community.

    According to our contractor, Siemens, who is installing them, they are fixture agnostic, they just want to install a product that will meet the needs of the community. How feasible that is after we have purchased the ones we have, I do not know. I am just repeating what Paul Douglas said in public at a city council meeting.

  12. DavisBurns

    “Even with shades drawn there was enough light that she could not sleep and was making do with a sleeping bag in their family room. ”

    I can only hope that she has complained to the city and ask for mitigation.

    There are health effects from sleeping in the light of blue shifted light, including depression, sleep disturbance and disruption of hormones that control appetite.

    From a 2012 Harvard health letter:

    “Even dim light can interfere with a person’s circadian rhythm and melatonin secretion. A mere eight lux—a level of brightness exceeded by most table lamps and about twice that of a night light—has an effect, notes Stephen Lockley, a Harvard sleep researcher. Light at night is part of the reason so many people don’t get enough sleep, says Lockley, and researchers have linked short sleep to increased risk for depression, as well as diabetes and cardiovascular problems.”

    And NIH says, “On 14–15 September 2006 the National Institute of Environmental Health Sciences (NIEHS) sponsored a meeting that focused on how best to conduct research on possible connections between artificial lighting and human health. A report of that meeting in the September 2007 issue of EHP stated, “One of the defining characteristics of life in the modern world is the altered patterns of light and dark in the built environment made possible by use of electric power.” The meeting report authors noted it may not be entirely coincidental that dramatic increases in the risk of breast and prostate cancers, obesity, and early-onset diabetes have mirrored the dramatic changes in the amount and pattern of artificial light generated during the night and day in modern societies over recent decades. “The science underlying these hypotheses has a solid base,” they wrote, “and is currently moving forward rapidly.”

  13. darelldd

    > LED lights produce 15% to 20% more sky glow than the lamps they replace because of the eye’s sensitivity to blue light at lower levels <

    As a universal statement, this is confusing, and inaccurate. I can easily create an LED lamp that reduces "sky glow" (can we quantify that?) by 50% as compared to the lamp I'd replace. First of all, LED fixtures can produce light that is even LESS blue than the current lights – if that's what we wished to accomplish. Heck, we can make them all red. Or amber. And even if the light is bluer than what we have, there are so many factors that can mitigate the sky glow, that this statement makes no sense to me.

  14. DavisBurns

    Sky glow occurs from both natural and human-made sources. The natural component of sky glow has five sources: sunlight reflected off the moon and earth, faint air glow in the upper atmosphere (a permanent, low-grade aurora), sunlight reflected off interplanetary dust (zodiacal light), starlight scattered in the atmosphere, and background light from faint, unresolved stars and nebulae (celestial objects or diffuse masses of interstellar dust and gas that appear as hazy smudges of light). Natural sky glow is well quantified. In this publication, further discussion of sky glow considers only human-made sources.

    Electric lighting also increases night sky brightness and is the human-made source of sky glow. Light that is either emitted directly upward by luminaires or reflected from the ground is scattered by dust and gas molecules in the atmosphere, producing a luminous background. It has the effect of reducing one’s ability to view the stars….from The National Lighting Research Center

  15. DavisBurns

    Darelldd…I am referring to the lamps we removed in Davis and the lamps we installed in Davis. I agree completely, the industry CAN make them any color they want, however they DON’T make street lights in colors warmer than 3500K. Ours are 4000K.

  16. John Obermeier

    Responding to darelldd: The topic may be confusing, but the statement is accurate. Following is a quotation from “Visibility, Environmental, and Astronomical Issues Associated with Blue-Rich White Outdoor Lighting” published by International Dark-Sky Association on May 4, 2010

    “At sites near light sources, such as within and near urban areas, the increased scattering from blue-rich light sources leads to increased sky glow (Luginbuhl et al., 2010; Figure 4). The bluest sources produce 15% to 20% more radiant sky glow than HPS or low- pressure sodium (LPS). This effect is compounded for visual observation, as practiced by casual stargazers and amateur astronomers, by the shift of dark-adapted vision toward increased sensitivity to shorter wavelengths. In a relatively dark suburban or rural area, where the eyes can become completely or nearly completely dark-adapted (scotopic), the brightness of the sky glow produced by artificial lighting can appear 3–5 times brighter for blue-rich light sources as compared to HPS and up to 15 times as bright as compared to LPS.”

    As to quantifying sky glow, one measure used by astronomers is the “SQM” — a measure of the magnitudes per square meter based on a sensor pointed directly up. The magnitude scale is non-linear — each change in magnitude is 2.5 times change in light intensity. I have been recording SQM readings at the same location on my property in Davis on a routine basis. So far, my records show a 14% increase in sky glow since May 26, 2014 when the new LED street lights were installed. This data is based only on measures when the moon was well below the horizon. SQM measures are widely used among astronomers and are frequently reported along with other technical information on published photographs.

    Here is some general information about visible light and scatter. The blue end of the visible spectrum scatters more than the red end of the spectrum. This is why we see blue sky during bright sunlight. When there is a longer path length through the atmosphere between us and the sun at sundown, the blue is filtered out leaving mostly the red-orange. I hope this makes it a bit less confusing as there is a direct connection between blue shifted light sources and increased scatter. Increased scatter also means that the SQM sensor pointed straight up encounters more scattered photons, thus making the sky brighter.

  17. DavisBurns

    Matt, you said “the lights are not the only thing that is being moved into your space. Improved public safety for you and your family and your neighbors is also being moved into your space. Are you saying that you do not value that increased public safety?”

    In the vast majority of cases, we are NOT talking about installation of additional lighting. We are complaining about the replacement of one fixture with another. In that case, how has harsh lighting with significant glare an improvement in public safety?

    What we have done is remove a public benefit–the ability to see the heavens above.

    1. Matt Williams

      DB, the old lights in many cases were little more than no light at all. Having no light, or very little light, does present a significant safety hazard for many people. In many, many cases replacing the old dim lights with the new lights is effectively going from no light to light.

      I was in a conversation the other day about the F Street Garage, and every one of the women who participated in the conversation said that they “would not park in the F Street Garage because it is so dark and they do not feel safe in those kinds of dark places.” Their point made sense to me … and appears to have direct application to darkness when parking on the street just as much as darkness when parking in a garage.

      1. DavisBurns

        Matt, regarding parking garages, California’s new Title 24 Energy Efficiency Standards went into effect on January 1, 2014 and they dictate how much light can be used in parking garages:

        “For the first time, lighting in parking garages, lots, and loading and unloading areas will also be required to have occupancy controls, with at least one step between 20 and 50 percent of full lighting power. Parking garages will be allowed a maximum of 500W per occupancy sensor. Case studies show that installing adaptive LED lighting in parking garages typically yields energy savings between 40 and 70 percent, depending on occupancy rates, light sources and other variables.”

        All I can say abut low level street light is that low level lighting allows my eyes to adapt to the dark and then I can see more whereas the new lights are too bright and leave me needing even more light when I move into the shadows. I don’t think its possible to light the night enough to shine light on every possible parking place along the streets. When I open my car door, the interior light allows me to see my footing on the street and/or sidewalk. With the new streetlight, I need to take a flashlight with me to walk around the block. The lights are so bright, I am night blind when I step from where the light shines into the shadows. I did not need to do that with the old lights. I admit our neighborhood seemed to have decent lights–not the yellow orange low pressure sodium. When we have inadequate lighting, I am just asking that we improve the lighting and not just INCREASE the lighting because they are not the same.

        Your friends who feel safer with more light are not alone but the operative word is ‘feel’. Universally, people feel safer with more light but we just cannot find data that says they are actually safer. We do not distinguish between personal safety to avoid tripping on heaved sidewalks and safety from crime.

        You might be interested in this article:

  18. DavisBurns

    “I can’t imagine why we’d choose anything over about 3500k to start with when converting to LED from our astonishingly low Kelvin exiting lights.”

    I think the quick answer is a salesman probably sold us the product. I’d like to know how they were chosen but that information is not forthcoming. I have information about the goals of the project, the cost of the project and the contract with Siemens but I do not know what the criteria was or if they even established criteria other than save money, reduce CO2 emissions and improve public safety (whatever that means).

    Another question I have, is if the six LEDs in the residential lamps (the arterial and major streets have higher wattages and more LEDs per lamp) can be repositioned so they create less glare. I have read that LEDs can be pointed in the direction the light is desired. Perhaps this is something only done at the factory, but it is used as a selling point. I believe the lamps we have , have the diodes pointed to the side and the front as well as pointing down which would explain some of the glare issues.

  19. DavisBurns

    For those of you who remember Julie Partansky, I found this 3 page letter she wrote to UCD about their new housing project in 2002 in which she read everything written about the EIR and then asked questions no one else asked. She included many pages about light pollution, crime and its inverse relation to light at night and other good stuff. It gives me a good idea what she would have to say about these new streetlights.

  20. Pingback: Street lights–what are the issues? | .:Da...

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