Better Streetlights for Tulsa

[Hoss]

I honestly havent even noticed any difference with the lights off in the areas of I have been in.  There is so much ambient light from the rest of the city (all the QTs perhaps  )that you can see quite well.

But just wait.  Three or four years ago when this was done, there wasn't much outrage until some ill-advised pedestrian tried to cross 244 in an unlit section of the highway and someone killed him.  That got the lights turned back on.

[sgrizzle]

But just wait.  Three or four years ago when this was done, there wasn't much outrage until some ill-advised pedestrian tried to cross 244 in an unlit section of the highway and someone killed him.  That got the lights turned back on.

No amount of lighting fixes stupid.

[dsjeffries]

No amount of lighting fixes stupid.

+1

[patric]

No amount of lighting fixes stupid.

I responded on the "Expressway Lights" thread...
http://www.tulsanow.org/forum/index.php?topic=4110.msg152251#msg152251

[patric]

Bluish-white streetlights are not only garish and uninviting, but here are a few other reasons to avoid them:

http://docs.darksky.org/PR/PR_Blue_White_Light.pdf

Yes, color does matter, more than just aesthetics.  An excerpt from an analysis of blue-rich lighting from a lighting forum:

For decades our understanding of circadian effects in animals tied melatonin suppression directly to rod and cone sensitivity in the eye.  The past decade of research that Holzman refers to ('What's in a Color? The Unique Human Health Effect of Blue Light' by David C. Holzman ) seems to make a sound argument, that it is not rods and cones but these third receptors -- melanopsin ganglian retinal cells -- that are driving circadian effects (plus others, perhaps even fear of the dark?). 

This means that the blue end of the visible spectrum, where peak output is found in most LED lights, is powerful.  Perhaps blue light in the day time can have some powerful, positive effects...  more significantly to outdoor lighting applications, blue light can have disproportionately powerful negative effects at night. 

If the research Holzman points to is sound, then we should consider carefully before advocating blue-intensive light sources, such as LEDs, in night-time lighting applications (i.e. all outdoor lighting).  In addition to the intensified Light Pollution concerns, blue light at night seems to be the biggest culprit in circadian disruption and those related risks of sleep disorders, depression, and cancer.

[patric]

Simonson and Tulsa Mayor Dewey Bartlett think they've come up with a bright idea to turn the lights back on and save the city money. The city is applying for $750,000 in stimulus money to replace some current street lights with LED lights. If approved, the money would come from the Department of Energy and be part of the city's energy efficiency strategy.
http://www.newson6.com/Global/story.asp?S=11805839

I dont know if that efficiency strategy involves consulting a lighting designer independent of the utility company, but it probably should.
It might not hurt if the city talked to the people that design lighting at hospitals, since their focus is lighting that actually benefits improved vision at night (even by visually impaired or elderly people).

Compare the lighting of St John Medical Center to that of a McDonalds or WalMart and you will see what I mean.

The days of specifying street lighting on an electric provider's need to sell off-peak generating capacity at night needs to end.  We just dont have the money anymore. 
Utilities should turn instead to promoting electric cars that plug in overnight to meet their excess capacity problems, not bad streetlighting.

[patric]

A lighting engineer I know is moving to Alpine TX, where they are expected to begin trials of LED streetlights that change hues and intensities as the night progresses.

"You would have a varied light color from 4200K at dusk to 2700K say at midnight.  We would not only change the light (color) temp but also the intensity would be reduced from say 5600 lumens to 2300 lumens (stepped down)."

So at sunset, the streetlight starts out brighter, and closer in color to daylight, but towards midnight (when eyes have adjusted to night) the streetlight has shifted to a warm incandescent and is half as bright.

That's cool.

[Red Arrow]

Where does 2700K fall in the wavelength chart?  You posted some charts last October (page 5 this thread) with some interesting info but I don't see the relationship between wavelength and temperature.  (It's late, maybe it's there and I just didn't see it.)

[patric]

Where does 2700K fall in the wavelength chart?  You posted some charts last October (page 5 this thread) with some interesting info but I don't see the relationship between wavelength and temperature.  (It's late, maybe it's there and I just didn't see it.)

"Color Temperature" is just a way of referring to where a light source falls on the Kelvin (K) scale.

2700 degrees Kelvin (written as 2700K) would be warmer in color, and closer to incandescent (which is around 3000K) than, say, a colder bluer color temperature like a 6400K (many "white" LED's).

Warmer colors are more natural, inviting and pleasing to the eye at night, but currently LED manufacturers are getting the most efficiency (lumens of light per watt of electricity) from blue-rich sources, so that is what they are marketing.  We are just expected to go along with garish looking lights right now in much the same way the early fluorescent manufacturers convinced us their greenish-fluorescent lights were the way to go in the 50's.
Today, fluorescent lights have much better color than the early ones, and I dont think we will have to wait as long for LED's to mature as we did fluorescent tubes.  3000K LED's are around but not being aggressively marketed as the brighter, bluer ones.

If municipalities insist on better color from LEDs the manufacturers will follow.  It's just we dont need to jump on the "blue light" bandwagon simply to be able to say we have LED streetlights.

FYI this is much more than just aesthetics.  Blue-rich light at night is bad because it interferes with the body's day/night rythym (by suppressing natural nighttime Melatonin production).  I can go into the medical information later, but here is some reading:
http://docs.darksky.org/PR/PR_Blue_White_Light.pdf
which dovetails nicely into the American Medical Associations' (AMA) position on health effects of stray lighting:
http://docs.darksky.org/Docs/AMA%20Light%20pollution.pdf

[Red Arrow]

I was wondering where 2700K fell with respect to the Scotopic, Mesopic, Photopic vision wavelengths.

I found something from Burlington, VT regarding the color they want.  Since they don't give wavelengths or spectral density, I would like to hear your opinion.

"High Pressure Sodium (HPS) lamps, while very efficient and long lasting, emit an orange-yellow light that distorts color as well as our ability to identify features at a distance. Metal Halide lamps emit a cool white light which makes for more accurate object identification and adds to our sense of security.  This white light creates a skyglow similar to moonlight rather than the orange glow of HPS, and are only slightly less efficient at commonly used wattages.  Metal halide is the preferred lamp for lighting applications in Burlington for both it's color rendering and energy efficiency."

They used it's in place of its in the last sentence, not me.
I printed the pages out as a pdf so the URL isn't on the bottom.  I'll try to find it again if you want.

[patric]

"Metal Halide lamps emit a cool white light which makes for more accurate object identification and adds to our sense of security.  This white light creates a skyglow similar to moonlight rather than the orange glow of HPS, and are only slightly less efficient at commonly used wattages.  Metal halide is the preferred lamp for lighting applications in Burlington for both it's color rendering and energy efficiency."

It sounds like they just quoted the lighting manufacturers sales brochure.
They were almost right when they said that Metal Halide creates a skyglow similar to moonlight -- about three to four times as much skyglow as regular Sodium streetlight, due to the Rayleigh Effect of water vapor scattering blue light.  But do you really want skyglow of any color when skyglow is an indicator of wasted light?

Bringing us back to the types of vision

Scotopic Vision (moonlight) 10-² to 10-⁶ cd/m² (or 'nits' for billboard people).
Mesopic Vision (porch light, residential streetlight) 10-² to 1 cd/m²
Photopic Vision (brightly-lit city centers, gas stations, billboards, and daylight) >1  cd/m²

(To give some idea as to scale of 'nits' or Candellas per Square Meter (cd/m²), Tulsa's LED billboards are 6,500 nits in daylight, 500 nits at night, for example.)

Where light of a color temperature of 2700 degrees Kelvin falls with respect to these types of vision depends upon the intensity of the 2700K light source.

At very low light levels (Scotopic) the eye is more sensitive to shorter-wavelength, bluer light (starlight, twilight, moonlight)

but some lighting manufacturers have assumed this would also be beneficial at much higher levels when in fact at higher levels different components of the eye are at work.

Here's another explaination of Color Temperature:
http://www.sizes.com/units/color_temperature.htm

So if I were to over-simplify a presentation for the mayor or council, It would be something to the effect:
The ideal outdoor lighting color temperature is 3000 degrees Kelvin, which is the color of incandescent light.

[patric]

No amount of lighting fixes stupid.

In the draft for the PLANiTULSA Downtown Area Master Plan, there is only one paragraph that made it in about improved lighting:

17. Appropriate lighting should be
provided to encourage a sense of
safety and ease for pedestrians
throughout Downtown. Similarly
appropriate lighting for vehicles is to be
provided. The excitement, identity, and
sense of place which lighting can provide
is to be considered in all public and
private development. Energy conservation and "dark technology" is a key
component in selection of lighting system.

What happened to providing lighting for the purpose of improving human vision?
...and can anyone tell me what they are calling "dark technology"?

The sketches that bother to show lighting all still show Acorns and Drop-lens lights, all high-glare (and high energy waste).  A 2006 energy audit revealed a correlation between the installation of inefficient Acorn-style decorative lights and spiraling streetlight energy costs (doubling between 2003 and 2006), and yet we still maintain that course while we lay off police and firemen?

There is now also an EnergyStar rating for streetlights, why no mention of requiring that for all new streetlights?

[godboko71]

That is worrisome that with all this planning something as important as lighting fell by the way side.

[patric]

Seeing this Italian streetscape is worth the view, even if you dont care about streetlights:

[Red Arrow]

Seeing this Italian streetscape is worth the view, even if you dont care about streetlights:

I like the lighting but am surprised that you haven't stated that the color is too blue/white.  Do you have the spectrum on those lights compared to what you seem to prefer?