Streetlighting Concerns

I submitted the following letter to the editor to the Dodgeville Chronicle this evening:

Dear Editor:

Have you noticed the gradual transformation of our streetlights in Dodgeville, Mineral Point, and other communities in SW Wisconsin?  The light source in our streetlights is changing.  High Pressure Sodium (HPS), which has been in use for decades and produces a orangish-white light, is being replaced by light emitting diodes (LEDs), producing a whiter light.

What’s not to like?  LED’s many advantages include: efficiency, longevity, instant-on and instant-off, and dimmability, to name a few.  But Alliant Energy is installing new streetlights that produce white light that is too blue, and the illumination levels are about 2.6 times as bright as the high pressure sodium streetlights they are replacing.

Lighting specialists use a term called “correlated color temperature” or CCT (in Kelvin) that allows us to compare the relative “warmness” (redder) or “coolness” (bluer) of  various light sources.   The illumination provided by candlelight has a CCT around 1500 K, HPS around 2000 K, an incandescent light bulb around 2800 K, sunrise/sunset around 3200 K, moonlight around 4700 K, and sunny noon daylight around 5500 K.  The higher the color temperature, the bluer the light.

Higher color temperature illumination is acceptable in workplace environments during the daylight hours, but lower color temperature lighting should be used during the evening and at night.  Blue-rich light at night interferes with our circadian rhythm by suppressing melatonin production, thus reducing sleep quality, and several medical studies have shown that blue light at night increases the risk of developing cancer, most notably breast cancer.  Even low levels of blue-rich light at night can cause harm.  While it is true that something as natural as moonlight is quite blue (4700K), even the light of a full moon provides an illumination level of just 0.01 foot-candle, far dimmer than street lighting, parking lot lighting, and indoor lighting we use at night.

LED streetlights are available in 2700K, 3000K, 4000K, and 5000K.  I believe that Alliant is installing 4000K streetlights in our area—I certainly hope they are not installing any 5000K.  What they should be installing is 2700K or 3000K.  These warmer color temperature lights are no more expensive than their blue-white counterparts, and the slightly higher efficiency of the blue-white LEDs is entirely nullified by over-illumination.

Even considering a modest lowering of light level with age (lumen and dirt depreciation), these new LED streetlights are considerably brighter than the HPS lights they are replacing.  Just take a look around town.  What is the justification for higher light levels in our residential areas, and when was there an opportunity for public input?  In comparison to older streetlights, the new LED streetlights direct more of their light toward the ground and less sideways or directly up into the night sky, and that is a good thing.  But now the illumination level is too high and needs to be reduced a little.

If you share my concerns about blue-rich lighting and illumination levels that are often higher than they need to be, I encourage you to contact me at oesper at mac dot com.  I operated an outdoor lighting sales & consulting business out of my home (Outdoor Lighting Associates, Inc.) from 1994-2005, and wrote the first draft of the Ames, Iowa Outdoor Lighting Code which was unanimously adopted by the city council in 1999, so I am eager to work with others in the Dodgeville area who are also interested in environmentally-friendly outdoor lighting.

David Oesper
Dodgeville

Dodgeville Streetlights

Has anyone else noticed how Alliant Energy is gradually replacing our orangish-white-light streetlights with bluish-white-light ones? The orangish-white-light streetlights are high-pressure sodium (HPS) with a correlated color temperature (CCT) of 1900K, whereas the bluish-white-light streetlights that are replacing them are LED with a CCT of 4000K, and, most notably, they are two and a half times as bright.

Even though I have written to both Alliant Energy and the City of Dodgeville, nothing has changed.

My questions, which are still unanswered:

What is the justification for increasing the streetlighting illumination level by two and a half times over what it has been for decades?

Why are we going from 1900K to 4000K (cold white), when 2700K or 3000K (warm white) is readily available and being used in many communities in the U.S. and Canada?

This same transformation is happening in Mineral Point, and probably many other communities in SW Wisconsin as well.

Is anyone else noticing how this is profoundly changing the rural character of our nighttime environment? Is anyone else concerned about this? The increase in glare and light trespass onto neighboring properties from these new LED lights is quite noticeable to me, even though they are nominally full-cutoff. Why? They are too bright, and too blue.

If anyone locally is reading Cosmic Reflections (and sometimes I wonder if anyone is…), and if you have noticed and are alarmed by these streetlighting changes, please contact me on blog or off blog (oesper at mac.com) and let’s meet and discuss a plan of action. Something needs to be done before it is too late and we are stuck with this very negative change to our nighttime environment.

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://i2.wp.com/www.rabweb.com/images/features/ledbollards/bollard-hero.png?resize=840%2C615&ssl=1
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