Bad Lighting at Dodgeville High School

At a school board meeting in November 2017, concerns were raised about inadequate lighting for evening school events, so the Dodgeville School District directed Alliant Energy to install some additional lights.  The lighting was installed during a warm spell in January 2018, and the photographs you see below were taken during the afternoon and evening of June 17, 2018.

Rather than being used only when school events are taking place in the evening, these terrible lights are on dusk-to-dawn 365 nights a year.  They are too bright, poorly directed, poorly shielded, and the glare they cause on W. Chapel St. and N. Johnson St. could pose a safety concern for pedestrians not being seen by drivers experiencing disability glare.  I can imagine that adjacent neighbors are not too happy with the light trespass into their yards and residences, either.

This is a perfect example of poor lighting design and unintended consequences.  How could it be done better?  Look for the solution below the following series of photos documenting the problem.

Bleacher path floodlight produces a great deal of uplight, and illuminates the disc golf course far more than the bleacher path
Bleacher path floodlight is mounted in a nearly-horizontal orientation
Bleacher path floodlight
Bleacher path floodlight
Bleacher path looking towards the bleachers

 

Bleacher path looking towards W. Chapel St.

 

Bleacher path at night
Bleacher path floodlight lighting up the disc golf course. Also note how much brighter the illumination is from the newly-installed blue-white LED streetlight as compared with the orangish light from the older high pressure sodium (HPS) luminaire.
Bleacher path floodlight lighting up the disc golf course and basket
Large tree being brightly illuminated all night long with bleacher path in foreground
Sub-optimal parking lot lighting at Dodgeville High School
Overflow parking floodlight

 

Two additional overflow parking lot floodlights
Overflow parking floodlight

 

Overflow parking floodlights

 

Overflow parking floodlight glare and spill light

 

Overflow parking floodlight glare onto W. Chapel St. in Dodgeville
Overflow parking glare and spill light onto W. Chapel St. in Dodgeville

Solutions

Pedestrian-scale 2700K LED “soft” lighting could be installed along the bleacher path
https://www.rabweb.com/images/features/ledbollards/bollard-hero.png
Or vandal-resistant bollards could be used—even low voltage lighting
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If floodlights must be used, shield them, point them more downwards, and turn them off after 11:00 p.m. each night (or have them on only while evening school events are in progress)

In fact, regardless of the lighting solution, the lights should be either turned off or dimmed down to a lower level later at night.  (Security cameras will see just fine at lower light levels if that is a concern.)

Good neighbor outdoor lighting means minimizing GLUT:

Glare—never helps visibility
Light Trespass—no point in putting light where it is not needed
Uplight—sending light directly up into the night sky is a total waste
Too Much Light—use the right amount of light for the task, don’t overlight

Avoid Blue-Rich LED Lighting

As Dodgeville (and many other towns and cities) are planning to replace their streetlights with LED luminaires, it is imperative that we use LEDs with a CCT (correlated color temperature) of 3000 K or less (Jin et al. 2015).  This is a “warm” white light (similar to incandescent) rather than the “cold” blue-rich light often seen with LEDs.  Outdoor LED luminaires often come in at least three “flavors”: 3000K, 4000K, and 5000K.  For example, American Electric Lighting’s Autobahn Series.  5000K luminaires provide the bluest light, and should be avoided at all costs.  Of these three, 3000K would be best, and if 2700K is offered, use that.

Why does this matter?  On June 14, 2016, the American Medical Association issued guidance on this subject.

High-intensity LED lighting designs emit a large amount of blue light that appears white to the naked eye and create worse nighttime glare than conventional lighting.  Discomfort and disability from intense, blue-rich LED lighting can decrease visual acuity and safety, resulting in concerns and creating a road hazard.

The detrimental effects of high-intensity LED lighting are not limited to humans.  Excessive outdoor lighting disrupts many species that need a dark environment.  For instance, poorly designed LED lighting disorients some bird, insect, turtle and fish species, and U.S. national parks have adopted optimal lighting designs and practices that minimize the effects of light pollution on the environment.

Recognizing the detrimental effects of poorly-designed, high-intensity LED lighting, the AMA encourages communities to minimize and control blue-rich environmental lighting by using the lowest emission of blue light possible to reduce glare.  The AMA recommends an intensity threshold for optimal LED lighting that minimizes blue-rich light.  The AMA also recommends all LED lighting should be properly shielded to minimize glare and detrimental human health and environmental effects, and consideration should be given to utilize the ability of LED lighting to be dimmed for off-peak time periods.

Incidentally, for your residential lighting needs, a good local source for LED bulbs that are not blue-rich is Madison Lighting.  They have many LED bulbs in both 3000 K and 2700 K. I use 2700K bulbs exclusively in my home, and the warm white light they provide is an excellent replacement for incandescent and compact fluorescent bulbs.  Never purchase LED lighting without knowing the color temperature of the lights.

If you’re skeptical that the color temperature of LEDs is an important issue, I suggest you purchase a 2700K bulb and a 4000K or 5000K bulb with the same output lumens and compare them in your home.  I believe that you will much prefer the 2700K lighting.  If 2700K lighting is best for your home, then why should it not be best for outdoor lighting as well?

Besides, most streetlighting is currently high pressure sodium (HPS), which is inherently non-blue-rich.  You will find that 2700K LED lights offers better color rendering than HPS without the need to go to even bluer lights.

If you have ever been irritated at night by an oncoming vehicle with those awful “blue” headlights, you’ve experienced firsthand why blue-rich light in our nighttime environment must be minimized.

Why are 4000K and 5000K LED lights so prevalent?  They are easier and cheaper to manufacture, but with increased demand of 2700K and 3000K LED lights, economies of scale will reduce their cost, which today are generally slightly higher than blue-rich LEDs.

Now, a bit more about why blue light at night can be detrimental to human health, and the primary reason why the AMA issued a guidance on this subject.

In addition to image-forming rods and cones, there exist non-image-forming retinal cells in the human eye called intrinsically photosensitive retinal ganglion cells (ipRGCs) that help regulate our circadian rhythms.  Studies have shown that blue light is far more disruptive to our circadian rhythms than redder light (Lockley et al. 2003).

Now, on to the environment.  Using a clever technique that compared sky brightness at several locations on several nights both with and without snow cover, Fabio Falchi (Falchi 2011) determined that at least 60% of light going up into the night sky is direct waste lighting, and 40% or less is reflected light.  This is as good an argument as any that we still have a long way to go towards using only full-cutoff luminaires that do not produce any direct uplight.  Blue light scatters much more in the night sky than red light, and this is due to Rayleigh scattering which tells us that the amount of scattering is proportional to the inverse of the wavelength of light to the fourth power, σs ∝ 1 / λ4.  This also explains why the daytime sky is blue.

Bluer wavelengths of light thus increase artificial sky glow to a much greater extent than redder wavelengths do.  Not only is an increase in blue light bad for astronomy, but its impact on the natural world is likely to be adverse as well.

Falchi recommends a total ban of wavelengths shorter than 540 nm for nighttime lighting, both outdoor and indoor.  He goes on to say that, at the very least, no more light shortward of 540 nm should be allowed than that currently emitted by high pressure sodium lamps, lumen for lumen.

References
Falchi, F. 2011, MNRAS, 412, 33
Falchi, F. 2016, The World Atlas of Light Pollution, p. 44
Jin, H., Jin, S., Chen, L., et al. 2015, IEEE Photonics Journal. 7(6), 1-9
Lockley, S. W., et al. 2003, J Clin Endocrinol Metab. 88(9), 45025