[Darksky][DSLF] Digest Number 415 (fwd)

Jan Hollan
Tue, 28 Aug 2001 14:37:09 +0200 (CEST)

more on LED signs and FCO...

---------- Forwarded message ----------
Date: 27 Aug 2001 09:08:11 -0000
From: DarkSky-listAyahoogroups...
To: DarkSky-listAyahoogroups...
Subject: [DSLF]  Digest Number 415

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There are 6 messages in this issue.

Topics in this digest:

      1. Re: FCO vr SCO
           From: ctstarwchrAaol...
      2. LED Traffic Lights
           From: "Mark Klosinski" <klosinskiAntelos...>
      3. Re: AASHTO
           From: ctstarwchrAaol...
      4. Re: LED Traffic Lights
           From: ctstarwchrAaol...
      5. VDOT has *Smart Roads*
           From: ctstarwchrAaol...
      6. Re: LED Traffic Lights
           From: "Randy John" <skysatAhome...>


Message: 1
   Date: Sun, 26 Aug 2001 08:55:58 -0000
   From: ctstarwchrAaol...
Subject: Re: FCO vr SCO

--- In DarkSky-listAy....., "Fabio Falchi" <fabio.falchiAl.....> wrote:
> Why do you use a percentage when the simplest thing is to use
> the light intensity in candles/klumens? The intensity at various
> angles is plotted or tabulated on the fixtures tech data sheet of
> the manufactures, so that we know how the product behaves.

Hi Fabio:

What you say is absolutely true and I agree completely from a 
luminaire design specification standpoint.  However, most people not 
directly involved in the design process do not understand how to 
decipher and evaluate photometric or isofootcandle plots.  Stating 
the illumination distribution properties in percentages tends to 
enhance the level of understanding by the group as a whole.  The 
Illumination Engineering Society of North America (IESNA) also states 
fixture luminance distribution properties in percentages as well.  

When presenting this information to legislators they can immediately 
visualize what we are saying if speaking in percentage of waste.  To 
present them with lumens, lux or footcandles of illuminance, and 
candela of luminance per square meter at a given angle merely makes 
their eyes glaze over with confusion, and rightly so.  Most average 
people do not know the difference between a lumen and a lemon, mainly 
because the terms and concepts of illumination design are not a part 
of their daily lives.

When giving presentations, I always strive to use the most effective 
means with simple terminology to help others achieve a good level of 
understanding.  Percentages allow accurate mental images to rapidly 
be formed, but 10 candela per 1000 candela of luminance at a given 
angle is a very complex issue for most people to rapidly image in 
their mind.  Hope it helps.

Clear skies,


Message: 2
   Date: Sun, 26 Aug 2001 10:02:28 -0400
   From: "Mark Klosinski" <klosinskiAntelos...>
Subject: LED Traffic Lights

Hi all:

Has anyone in this group experienced or heard anything about the new "lamps"
for traffic lights? (I assume they are LED Lamps.  Maybe about a hundred
little lights.)  I first noticed it around Harrisonburg, VA about two months
ago. The lights are brighter than the normal lights.  (Does anyone have any
readings?)  The lights were not particularly bad in the city.  But on my way
home from a star party the other night, I noticed some on a highway outside
the city.  Once I went through the light, it was light I was moving into a
vail of darkness.  It was kind of frightning.  I could not see a thing on
the other side of the traffic light until my eyes readapted.

Any information on these light would be appreciated.

clear skies,
Mark Klosinski


Message: 3
   Date: Sun, 26 Aug 2001 15:50:18 EDT
   From: ctstarwchrAaol...
Subject: Re: AASHTO

In a message dated 8/26/01 12:53:25 AM Eastern Daylight Time, 
callistoAoptonline... writes:

> FWIW, As part of the NY effort, Gail Clyma has found out that AASHTO
> anticipates having an updated guide out around May-June of next year.


This might be good news, but it might also tend to bring even more lumens 
into our environment depending upon the AASHTO interpretation of what *better 
lighting* means.  "An Informational Guide for Roadway Lighting" published by 
AASHTO was last revised in 1984 before FCO was the preferred method of 
roadway lighting.
The facts indicate that traffic fatalities among elderly drivers have risen 
dramatically (33%) in the past ten years in spite of the fact that traffic 
fatalities have gone down by 9% overall according to October 6, 2000, AASHTO 
Journal Volume 100, Number 40.  This document states that The Road 
Information Program (TRIP), a nonprofit research group, has made the 
following recommendations for signage and roadway lighting: 

- clearer and less complex signage that is easier to follow  (makes sense)
- larger lettering on signs   (also makes sense)
- better street lighting, particularly at intersections (please define 

Recommendations for reducing fatalities at intersections: 

- bright, luminous lane markings (facilitated by what means?  More lights??)
- overhead indicators for turning lanes (proven to reduce accidents)
- overhead street-signs on both sides  (also proven to reduce accidents)
- add or expand left-turn lanes and make sure they are adequate in length 

The document also states that federal reports indicate that the aging process 
gradually leads to reduced visual acuity, slower reaction times, losses in 
information processing ability, and reduced neck and upper body flexibility.  
Better lighting to folks like us means a dramatic decrease in visible glare 
without loss of illumination of the task area, but what does *better* mean to 
TRIP when they make these recommendations to the AASHTO and the Federal 
Highway Administration?  Has anyone read or have a copy of, "The Older Driver 
Highway Design Handbook", published by the Federal Highway Administration?

Although I have not seen the specifications yet, it is very likely that 
AASHTO uses standards for roadway lighting based on recommendations of the 
Army Corps of Engineers, which still goes by IESNA RP-8-83 recommended 
practices.  Since the recently published RP-8-00 is ANSI approved it should 
be a no-brainer for the ACE to adopt the current IES recommended practices.  
Glare reduction with outdoor lighting must be pursued aggressively because 
glare is the foremost contributor to reduced visual acuity in the nighttime 

Clear skies,
Cliff Haas
 ||    /  FCO  \
 ||   / the way \
 ||  /   to go!     \
 ||/      www.      \
 /|  darksky.org   \

Light Pollution Awareness Website

[Non-text portions of this message have been removed]


Message: 4
   Date: Sun, 26 Aug 2001 16:41:24 -0000
   From: ctstarwchrAaol...
Subject: Re: LED Traffic Lights

--- In DarkSky-listAy....., "Mark Klosinski" <klosinskiAn.....> wrote:
> Has anyone in this group experienced or heard anything about the
> new "lamps" for traffic lights? (I assume they are LED Lamps. 
> Maybe about a hundred little lights.)  I first noticed it around
> Harrisonburg, VA about two months ago. The lights are brighter
> than the normal lights.  (Does anyone have any readings?)

Hi Mark:

What you have experienced sounds very much like the testimony of 
others (self included) who have encountered these new LED traffic 
signals in high contrast (dark) areas.  Here is one clue to help 
determine whether a traffic signal is the new LED type.

If you notice a black masque separating each point of illumination in 
the signals for red, yellow, and green, it is a pretty good bet you 
are behind a new LED retrofit.  The matrix appears much like a 
ceramic tile floor (tiles represent light source) with the grout 
representing the masque.  This is not typical of ALL LED traffic 
signal designs as you will see at one link provided below, however.

More info about LED traffic signals is available at:

"LED Traffic Signal Lighting" - US Army Forces Command Energy Program

"LED Traffic Signal Market Transformation: An Update With Boston-Area 
Case Studies," published by the American Council for an Energy-
Efficient Economy

Product information

"LED Traffic Signal Program"

A search on the web will provide more information...

Hope it helps!


Cliff Haas


Message: 5
   Date: Sun, 26 Aug 2001 20:44:18 EDT
   From: ctstarwchrAaol...
Subject: VDOT has *Smart Roads*


The Virginia Department of Transportation (VDOT) 
[http://www.vdot.state.va.us], in cooperation with Virginia Tech's 
Transportation Institute (VTTI) [http://www.ctr.vt.edu] and the Federal 
Highway Administration (FHWA) [http://www.fhwa.dot.gov], developed a concept 
known as the "Smart Road" which allows them to simulate various driving 
conditions in an effort to find solutions that improve highway safety.  

Included are the ability for VDOT to simulate weather and the system also has 
3 different lighting systems to study the effectiveness of reducing 
accidents.  I'm wondering if they have been experimenting with various 
different FCO luminaires.  Does anyone know if they have?  I tried contacting the two VDOT engineers via email but a few minutes later I received bogus address reports coming back.  Maybe the VDOT email server was down for the weekend?


This link might split into two or three lines.  Be sure to cumulatively paste 
each line to your browser.

Clear skies and good seeing,
Keep looking up!

Cliff Haas
Chairman of Light Pollution Education
Astronomical Society of Greater Hartford

Light Pollution Awareness Website (LiPAW)

Help rid your area of obtrusive outdoor lighting.
Visit http://www.darksky.org  Join the IDA today!

[Non-text portions of this message have been removed]


Message: 6
   Date: Mon, 27 Aug 2001 06:13:22 -0000
   From: "Randy John" <skysatAhome...>
Subject: Re: LED Traffic Lights

    Here are some more LED links to add to Cliff's.


----- Original Message ----- 
From: "Mark Klosinski" <klosinskiAntelos...>
To: "DarkSky-list" <DarkSky-listAyahoogroups...>
Sent: Sunday, August 26, 2001 2:02 PM
Subject: [DSLF] LED Traffic Lights


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