Blinding Headlights

I’ve lived in Tucson, Arizona for ten months now, and I have to tell you, it is no fun driving here at night. While it is a joy living in a city that for a change isn’t horribly overlit and that takes light pollution seriously (though that is starting to erode), it is often hard to see at night because of the many vehicles on the road with blinding headlights. In recent years, this has become a huge problem throughout the U.S., and the National Highway Traffic Safety Administration (NHTSA) and the Insurance Institute for Highway Safety (IIHS) needs to act quickly and decisively to deal with this dangerous nuisance.

Not only have headlights gotten brighter and bluer (which makes glare much worse), many vehicles have multiple sets of headlights, including “fog lights” that are anything but. High-profile vehicles such as pickup trucks and SUVs are especially bad when it comes to causing blinding glare for smaller, less extravagant vehicles. Jacked-up pickup trucks are the worst, and there are a lot of them here.

When one of these headlight-offensive vehicles is heading towards you, it makes it difficult to see the road ahead. It is especially hard to see pedestrians and bicyclists. Pavement markings are also harder to see because of the glare from the oncoming vehicle, especially when those lines are badly faded and in need of re-painting (as they often are here).

Tucson has far too many busy intersections without a protected left turn, and if you find yourself in a left-turn lane being stared down by a headlight-offensive vehicle in the opposite left-turn lane, the glare blinds you so much that it is difficult to see oncoming vehicles in the through-traffic lanes.

When a headlight-offensive vehicle comes up behind you and, as they often do, practically rides your bumper because driving at or near the speed limit isn’t fast enough for them, you’re hit with their intense glare in all three rear-view mirrors. This makes it harder to see the road ahead, and you have to slow down—which tends to aggravate them more than they already are. If you’re lucky, they can pass you—though sometimes they will illegally cross a double yellow line to do it.

Because of all these intense and unregulated vehicle headlights, I now avoid driving at night whenever possible.

Sure, headlights like these helps the perpetrator see better so they can drive down the road at night exceeding the speed limit (which is seldom enforced here, by the way), but everyone else—drivers, bicyclists, and pedestrians—is blinded.

What are the specific problems with modern vehicle headlights that need to be addressed, and what are the solutions?

  • Problem: The average vehicle’s total headlight lumen output (and individual headlight luminance) has dramatically increased in recent years, causing a corresponding increase in discomfort and disability glare for everyone else.
  • Solution: Headlights would not have to be so bright if speed limits were lower at night on many city streets and thoroughfares, and if the posted speed limits were actually enforced.
  • Solution: Implement adaptive driving beam (ADB) technology that uses sensors to detect oncoming traffic and adjusts the projected beam pattern to allow plenty of light for the driver without blinding other motorists. (ADB is widely used in Europe, but is not yet legal in the United States.)
  • Problem: Light-emitting diode (LED) and High Intensity Discharge (HID) headlights emit more light at the blue end of the visible spectrum than traditional warm-white or yellowish halogen headlights do, and these bluer lights result in significantly greater visual discomfort and impairment for other drivers.
  • Solution: Limit the amount of blue light that headlights can produce.
  • Problem: Poor headlight aim leads to dangerous glare for others.
  • Solution: Require regular headlight aim inspections and adjustments. Anytime a vehicle’s suspension is lifted, require headlight aim to be adjusted downward accordingly.

Here’s a petition you might want to sign:

https://www.change.org/p/u-s-dot-ban-blinding-headlights-and-save-lives

I’d like to close this article by quoting one of the many insightful comments in the Comments section of the New York Times article listed under References below.

Like everything else, it is no longer about the collective good and the laws that protect it. Individualism now rules—individual freedom. Headlights have become a First Amendment issue—an element of free speech.

And they have become part of the conservative anti-government backlash. Laws regulating headlights are seen as government intrusion into personal freedoms. It is seen by many to be like the COVID mask issue. Too many people think personal freedom trumps everything else–even collective health and safety.

And there is a free-market aspect to this. Manufacturers are looking for ways to add features to cars that will make them more attractive to buyers. They know the lights are unsafe, yet they put them on their vehicles.

America has lost all common sense.

Michael
Evanston, IL | June 9, 2021

Mark my words, if we keep heading down this path of excessive individual freedom (read: selfishness) without significant responsibility for the common good (that means everybody, not just your tribe), it will be our undoing. The United States will become a miserable place to live for the majority of us for at least a generation. I’m not hopeful that we can turn this around in time. Too many of us are “asleep at the wheel” and too easily swayed by misinformation and propaganda.

References

Mele, Christopher. “Blinded by Brighter Headlights? It’s Not Your Imagination.” New York Times, June 5, 2021, https://www.nytimes.com/2021/06/05/business/led-hid-headlights-blinding.html.

Turn Down the Lights, Turn Up the Stars

We are presently witnessing a rapid transformation of our outdoor nighttime environment as many older lighting sources such as high pressure sodium, metal halide, and fluorescent are being replaced with solid state lighting, specifically light emitting diodes (LEDs).  Many of the lighting decisions being made today with little or no citizen input will have consequences that impact our nighttime environment for decades.

Rather than continuing to subscribe to the “more is better, dusk-to-dawn” approach to outdoor lighting, we need to utilize this new technology in creative and innovative ways (many already available) to improve our nighttime built environment while minimizing lighting’s deleterious effects on the natural world.  Three paradigm shifts are needed.

Paradigm Shift #1
Less light will usually work just fine (a little light goes a long way)

Paradigm Shift #2
Dusk-to-dawn lighting → Lighting on Demand

Paradigm Shift #3
Full intensity lighting → Multi-Intensity Lighting (dimmable)

When choosing the amount of light you need, one should always consider the task or tasks needing to be performed.  For example, the amount of light needed to identify a rural intersection is much less than is needed to play a baseball game at night.  In both cases, though, the light needs to be restricted to only the area needing to be illuminated: the intersection or the playing field.

Another example.  When my wife and I bought a house in Dodgeville, Wisconsin back in 2005, our front porch had a 100-watt frosted incandescent light bulb to light the porch that we could turn on whenever we had company in the evening.  Thinking it too bright, we replaced the 100-watt bulb with a 60-watt bulb, then tried a 40-watt bulb, and finally a 25-watt bulb.  The 25-watt bulb adequately illuminated the porch and the stairs leading up to the porch, so in it stayed.

Then there is the issue of dusk-to-dawn lighting.  Many years ago, we switched outdoor lighting on or off as needed, but technological advancements later allowed us to have a light come on at dusk and stay on all night until dawn.  Now, think of all those lights burning when no one is there to use them.  If security is a concern, there is even newer technology that will do a far more effective job of detecting intruders than simply leaving a light on all night long.  In fact, a dusk-to-dawn light is not needed at all as part of an effective security system.  So, why not use 21st-century technology to have outdoor lights automatically turn on when needed and turn off when not needed?  Some LED light bulbs even come now with integrated occupancy sensors.  Lighting on demand could and should be replacing most dusk-to-dawn lighting within the next few years.

What about some roadway and parking lot lighting that must remain on all night long?  Those lights could be at full brightness during times of high traffic such as during the evening hours, but dimmed to 50% when traffic is lower, such as after midnight.  Once again, 21st-century technology makes this easy to do.

LED lighting lends itself very well to frequent on-off switching and dimming, but much of what is currently being installed is too blue.  As you can see in the table below, typical LED light sources have a substantial “spike” at the blue end of the visible light spectrum as compared with other white light sources.

Not only does blue light scatter more in the atmosphere and within our eyes, but many people perceive bluish-white light as colder, more clinical, than the warmer white light where this blue spike is absent, as shown below.  The blue spike in LED lighting can be removed either by using filtering, or by using a different phosphor that gives a warmer white spectrum.  Strongly preferred for both indoor and outdoor lighting are LED light sources with a correlated color temperature (CCT) of 2700K or 3000K.  2700K is the standard for indoor lighting, and yet 4000K is most often used for outdoor lighting.  Why?  Let’s move the standard for outdoor lighting to 2700K or 3000K.

By properly shielding lights so they only shine downwards, by using lights that are no brighter (or bluer) than they need to be, and by turning lights off when they are not needed—or dimming them during times of lower activity—we all will be helping to improve both our natural and celestial environment.

Turn Down the Lights, Turn Up the Stars *

* Suzy Munday, May 11, 2018

Additional Thoughts

In thinking about 21st-century lighting, one’s thoughts naturally towards 21st-century power generation.  We do not think often enough about the many advantages of a more decentralized power grid, where nearly everyone is generating some power with solar panels and small-scale wind turbines, as well as other local sources of energy such as geothermal.   As we once again consider building nuclear power plants (which will still be quite vulnerable to terrorism) and continue to build expensive fossil fuelish power plants and ugly high-voltage transmission lines, why not a paradigm shift towards decentralized energy production instead?

LED Residential Streetlight Debut in Dodgeville: Too Bright!

A new bright white LED streetlight made its debut in Dodgeville, Wisconsin on Friday, November 3, 2017, and it isn’t pretty.

The white-light LED streetlight is located at the NE corner of W. Washington St. & N. Johnson St. in Dodgeville.  The illumination level on the ground peaks at 3.15 fc.  An existing orange-light high pressure sodium streetlight at the SW corner of W. Division St. & N. Virginia Terrace peaks at 1.23 fc, which is typical.

Even though the reduction of uplight and near-horizontal light (i.e. “glare”) from this luminaire is a welcome improvement, an illumination level 2.6 times as bright as before is neither welcome nor justified.  Furthermore, lower illumination levels may be acceptable when using white-light LED luminaires in comparison with high pressure sodium (Glamox n.d.).  More research is needed on the effect of spectral composition on both brightness perception and, more importantly, visual acuity at various illuminance levels.

I do not have an instrument to measure the correlated color temperature (CCT) of this luminaire, but visually it looks to me to be around 4000 K, which is too blue.  I will check with the City of Dodgeville and report back here.  The International Dark-Sky Assocation (IDA) and the American Medical Assocation (AMA 2016) recommend using “warm white” LEDs with a CCT no higher than 3000 K, with 2700 K preferred.

References
AMA (2016), Human and Environmental Effects of Light Emitting Diode (LED) Community Lighting H-135.927.  Retrieved November 5, 2017 from https://policysearch.ama-assn.org/policyfinder/detail/H-135.927?uri=%2FAMADoc%2FHOD-135.927.xml.

Glamox (n.d.), The Glamox Brightness Sensitivity Test. Retrieved November 5, 2017 from http://glamox.com/gmo-recreational/led-brightness.

IDA (n.d.), LED: Why 3000K or Less.  Retrieved November 5, 2017 from http://www.darksky.org/lighting/3k/.

Oesper, D. (January 9, 2017), Avoid Blue-Rich LED Lighting.  https://cosmicreflections.skythisweek.info/2017/01/09/avoid-blue-rich-led-lighting/.

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