... They look so cute I wish I had a couple. If I had a farm, I would have 3
donkeys, 10 dogs, 30 cats, a dozen turkeys and 10 dozen chickens. I LOVE
chickens.

On Fri, 25 Jan 2008 10:38:43 -0800 (PST), furles@mail.croydon.ac.uk
wrote:

.... We used to have a strange lantern, it was a sort of rectangular
disk, think of something the shape of an inverted photographic
developing dish, with two 180W SOX lamps, mounted along the long
sides, with the gear mounted between them. These lanterns ware most
often seen suspended from catenary along the centre of roads. When I
went to Sheffield by coach last May there were still some along the M1
motorway. I've also seen these strange lanterns, grouped in fours,
used for high-mast lighting; eight 180W SOX lamps is a lot of light!

There is, if it still exists, a mid roadway, high mast, cable
suspension system like you describe on one of the major autoroutes
outside Montréal, and it has to be one of the most comfortable
lighting systems I've ever experienced. Personal taste such as it is,
I much prefer this type of arrangement over the typical SON systems we
find almost everywhere.

I understand why high CCT and CRI light sources would be desirable in
urban environments, and in particular areas with high pedestrian
traffic, but on major roadways, LPS allows me to "filter out" some of
the visual distraction and concentrate on the task at hand. On the
other hand, I often wonder if my depth perception isn't somewhat
impaired. Are there any studies out there that would suggest this
last point is, in fact, a valid concern?

Cheers,
Paul

Paul M. Eldridge wrote:
[snip]

I understand why high CCT and CRI light sources would be desirable in
urban environments, and in particular areas with high pedestrian
traffic, but on major roadways, LPS allows me to "filter out" some of
the visual distraction and concentrate on the task at hand. On the
other hand, I often wonder if my depth perception isn't somewhat
impaired. Are there any studies out there that would suggest this
last point is, in fact, a valid concern?

I think I may have reposted this reference long time ago, but just in case
you
missed it:

Quoting from K.D. Alexopoulos, General Physics, Optics, First Edition,
Athens
1966, page 133: (translation from Greek mine)

"...Although of very high efficiency, they are not often used for
lighting,
because the yellow light they emit may be considered "unpleasant" and does
not
render colors accurately. However, they are used in some cases (such as
for the
lighting of highways, rural roads, ship docks, train crossings, etc),
first
because the emitted light penetrates fog without being scattered
significantly,
second because the eye adjusts better under monochromatic light and vision
becomes sharper..."

FWIW, my own experiments with an LPS lamp long time ago seem to support
the last
part.

Cheers,
Paul
--
I.N. Galidakis

Years ago, some colleagues and I compared the visibility characteristics of
LPS, HPS and phosphor-coated mercury in a roadway lighting situation. We
matched luminances on various gray and neutral-colored objects and then
measured the visibility of those objects with a visibility meter. There was
little difference among the lamps as far as the overall visibility of the
objects was concerned; but we did notice that, under LPS lighting, visual
acuity (ability to see details) was somewhat better. That makes sense, of
course, since LPS is almost monochromatic and so produces less chromatic
aberration in the eye than the other sources. We didn't note any depth
perception effects.

Terry McGowan

On Sat, 26 Jan 2008 01:45:22 GMT, "TKM" <nom...@no.net> wrote:
Years ago, some colleagues and I compared the visibility characteristics of
LPS, HPS and phosphor-coated mercury in a roadway lighting situation. We
matched luminances on various gray and neutral-colored objects and then
measured the visibility of those objects with a visibility meter. There was
little difference among the lamps as far as the overall visibility of the
objects was concerned; but we did notice that, under LPS lighting, visual
acuity (ability to see details) was somewhat better. That makes sense, of
course, since LPS is almost monochromatic and so produces less chromatic
aberration in the eye than the other sources. We didn't note any depth
perception effects.

Terry McGowan

Thanks, Terry; I know very little about roadway lighting, so I
appreciate your comments. I guess the trend is towards high mast
HID/SON, which makes sense on many levels and if that's the case, the
days of LPS will soon draw to a close.

Now if someone could develop an intelligent version that automatically
adjusts light output based on traffic volume and/or time of night or,
better yet, changing road conditions (e.g., dry pavement versus snow
covered), comfort and safety could be further enhanced, plus the
energy savings would be substantial.

Cheers,
Paul

I google for s/p ratios, and find 1.41 for 2850 K incandescent and .8
for clear high pressure mercury vapor. Phosphored MV should have s/p
ratio slightly less than clear MV.

There is, if it still exists, a mid roadway, high mast, cable
suspension system like you describe on one of the major autoroutes
outside Montréal, and it has to be one of the most comfortable
lighting systems I've ever experienced. Personal taste such as it is,
I much prefer this type of arrangement over the typical SON systems we
find almost everywhere.

On 26 Jan, 06:14, d...@manx.misty.com (Don Klipstein) wrote:

I google for s/p ratios, and find 1.41 for 2850 K incandescent and .8
for clear high pressure mercury vapor. Phosphored MV should have s/p
ratio slightly less than clear MV.

What's s/p ratio?

I don't think there are any clear HP mercury lamps available here, at
least not ones for general purpose lighting use; there are specialised
ones.

Paul,

The Street Lighting Control you ask for already exist.

See a collection of Street Lighting Controls links on my del.icio.us
web site.
http://del.icio.us/JohnSRichards/streetlightingcontrols

There are about 75 URLs connected to this tag.
Please advise if there are others I should add.

Some of the most interesting are:
http://www.dellux.ca/
http://www.streetlightiq.com/
http://www.holophane.com/roam/default.asp
http://www.metrolight.com/

Hope this helps.

John S. Richards

Did you ever have any of the SLI/H linear sodium lamps over there? In
case anybody doesn't know what I'm talking about, they are these
things:

http://www.lamptech.co.uk/SLI.htm

The ones which I have are the same as the Atlas 140W one, but mine are
branded Thorn. They must have been fairly unusual even hear, as I'd
never seen one until a few years ago. The outer envelope and caps of
the 140W and 200W lamps are the same size as a three foot T12
fluorescent tube.

Did you ever have any of the SLI/H linear sodium lamps over there? In
case anybody doesn't know what I'm talking about, they are these
things:

http://www.lamptech.co.uk/SLI.htm

The ones which I have are the same as the Atlas 140W one, but mine are
branded Thorn. They must have been fairly unusual even hear, as I'd
never seen one until a few years ago. The outer envelope and caps of
the 140W and 200W lamps are the same size as a three foot T12
fluorescent tube.

Perhaps that's why I love clear HPM lamps so much. Because I was
born after they were changed. Some people find CFLs annoying. I can
practically read, write and do all my regular nightly chores under
clear HPM lighting. This kind of light makes me feel invigorated. Go
figure.

The OSRAM catalog lists their kind as NAT 200W-3.

It has a footnote on them saying "This type is not produced anymore, except as a
replacement until 1985".

I guess the above means OSRAM doesn't manufacture them anymore.

Doing a comparison on efficiency with the OSRAM NA 180W, I see:

Lamp lm
NA 180W 33000
SOX 180W 32000
NAT 200W 23000

Perhaps that's why it was discontinued.

On Sun, 27 Jan 2008 11:26:06 -0800 (PST), furles@mail.croydon.ac.uk
wrote:

Did you ever have any of the SLI/H linear sodium lamps over there? In
case anybody doesn't know what I'm talking about, they are these
things:

http://www.lamptech.co.uk/SLI.htm

The ones which I have are the same as the Atlas 140W one, but mine are
branded Thorn. They must have been fairly unusual even hear, as I'd
never seen one until a few years ago. The outer envelope and caps of
the 140W and 200W lamps are the same size as a three foot T12
fluorescent tube.

I'm afraid I can't provide you with a good answer on this; they may
have been used here in North America, but I'm not familiar with them.
Perhaps Victor or Terry can confirm this for us.

Cheers,
Paul

The story of low pressure sodium lighting is the U.S. is interesting
-- especially to lighting geeks I know parts of it because LPS
and HPS were both marketed for outdoor lighting in the 1980s and I
was usually the one to present the HPS side the of argument to city
councils, street lighting engineers and electric utilities. But, the
double-ended LPS lamps were not marketed in the U.S. -- at least
during my time in the lamp business from 1961 - 1999. Philips
introduced the "modern" LPS lamps to North America in Canada during
the late 70s - early 80s and promoted several important installations
including the Laurentian Autoroute which goes 55 miles from Montreal
north into the ski country. Much of it was continuously lighted and
it gave the N.A. roadway lighting industry a taste of the European
roadway lighting approach used in the Netherlands, Belgium, France
and, of course, in the U.K.

In 1982 Philips purchased Westinghouse Lighting which gave Philips
its first major entrance into the U.S. lighting market. LPS lamps
were unique and Philips had lots of experience with them so they were
promoted as new, exclusive, energy-saving products. LPS roadway
lighting systems then appeared in Long Beach, CA and several smaller
cities around the country.

Astronomers liked the monochromatic light output of LPS and organized
efforts to have them used for outdoor lighting around important
observatories. There were major installations in Tucson, AZ (Kitt
Peak Observatory); San Diego, CA (Mt. Palomar Observatory) and San
Jose, CA (Lick Observatory) as a result. LPS sockets grew to the
point that a company in Chicago began importing British LPS lamps
from GEC; but these were the single-ended designs so they could be
used as replacements for the Phiips products. Strategically, it was
a good move for the LPS market since two suppliers offered the
promise of competition (important to government buyers).

But HPS lamps had appeared in 1965 and the outdoor lighting industry
was already busy replacing HP Mercury with HPS when LPS lamps arrived
in the U.S. LPS promoters had a tough time for several reasons ---
color being one; but the main reasons were economic. HPS fixtures
could be retrofitted into systems using HP Mercury lamps (the main
source used in ourdoor lighting at the time) very easily sometimes
without even changing the luminaire. An LPS changeout required new
fixtures and the light distribution from the luminaires was such that
lighting uniformity suffered. LPS roadway lighting required either
more poles/mile or taller poles for uniform lighting and that drove
costs higher.

Then, the clincher came -- improved HPS lamp life. Once HPS lamps
were rated for 24,000+ hours, electric utilities lost interest since
those who provide street lighting service want the longest lamp life
possible. LPS lamp life at the time was rated at 18,000 hours
(Philips) and 20,000 hours (GEC).

Terry McGowan
--