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Sign of the times
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David Hess:

--- Quote from: Gyro on May 14, 2021, 08:28:04 pm ---One of my earlier memories is lying on the back seat of an Austin A30, feeling horribly travel sick, watching the orange low pressure Sodium lamps drift by.  >:D
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I have similar memories and thinking about it now, in order of time they went from largely low pressure sodium, to high pressure sodium, to mercury.


--- Quote from: james_s on May 15, 2021, 06:21:21 am ---It's certainly going to depend on where you are. Here in the USA mercury vapor absolutely dominated street lighting from about the late 1950s up into the early 1980s. Some areas used clear lamps and others used phosphor coated color corrected lamps, some seemed to use whatever they had on hand at the time. LPS (SOX) that was extremely common in the UK and Europe never really caught on here, there were pockets of them in a few specific areas, particularly in the vicinity of observatories but I've never seen one on a public road up here in the Northwest.
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I think it varied a lot between urban, suburban, and rural areas.  LPS was common in rural California where I was born but I never saw them in any large suburban or urban areas.  The small towns in the 1970s still had a lot of them.
james_s:

--- Quote from: David Hess on May 15, 2021, 06:36:39 am ---I think it varied a lot between urban, suburban, and rural areas.  LPS was common in rural California where I was born but I never saw them in any large suburban or urban areas.  The small towns in the 1970s still had a lot of them.

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I think it was a California thing. I could swear I saw a few LPS remaining in San Diego I think it was as recently as about 10 years ago. Seems like I heard they were common in Arizona too, or maybe it was New Mexico, I don't even recall now. Up here in my corner I never saw them on public roads anywhere, ever. Rural and urban areas alike went from mercury vapor to HPS and over the past 10 years have been shifting to LED.
Ed.Kloonk:

--- Quote from: vk6zgo on May 14, 2021, 08:36:14 am ---

On another trip to the UK, in 1974" I parked my pink Ford Cortina hire car in a smallish car park, & went to visit some people.
On my return, after dark, I couldn't find a pink Cortina, but there was a yellow one!

Not really that much of a hassle, as the key ring had the Reg number on it, but it had me going for a while.

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Might have been pink elephants that were involved?
richard.cs:

--- Quote from: bd139 on May 14, 2021, 09:36:13 pm ---Yeah that's a massive problem in London as a driver. While I certainly respect cyclists (as a former cyclist) it really annoys the hell out of my when someone comes flying at me on the opposite side of the road with a frigging strobe light going on. I can see you fine if it doesn't flash.  >:(

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The slow flashing ones are quite dangerous as the only light (and not generally lawful in the UK*). I remember pulling out of a junction having looked right-left-right and nearly hit a cyclist coming from the right whose light was off both times I looked in his direction. It must have been around 1-2 Hz. When I cycle I never use the flashing modes for this reason.

Coming back to streetlighting. Around here (Southampton UK) it was mostly LPS, with occasional HPS on major roads until maybe 5 years ago. Now residential areas are mostly fluorescent (!?) and dim or turn off from 1 am, most of the major roads are LED with some HPS left at big junctions.


--- Quote from: james_s on May 14, 2021, 08:51:33 pm ---Modern regulations requiring full-cutoff luminaires that do not emit any light above 90 degrees also create a problem of needing more of them to create even illumination and even then you end up with bright pools under the source with dark spaces between.

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The problem is retrofitting full-cut-off without changing anything else like pole heights or spacings. It's cheaper but you get this effect.

I can remember sections of the M25 having LPS on catenaries up the central reservation, like this http://imagizer.imageshack.com/a/img922/9831/kq2AUC.jpg I seem to remember the light was fairly even, but it's all gone now in favour of conventional poles. Perhaps maintenance is just easier/cheaper. Not all UK motorways have lighting, mostly the larger, busier ones and around junctions.


*You are allowed to use a light that flashes if it is CE marked and has no other modes. From memory though this is to meet the requirement to have lights, once you have a light that meets this you may be able to add additional lights of any type, not sure.
Zero999:

--- Quote from: james_s on May 14, 2021, 08:51:33 pm ---
--- Quote from: Rick Law on May 14, 2021, 08:31:04 pm ---I recall reading an article that highway/street lights in white is easier for older people to see.  I can't find that article anymore.

But, it makes sense -- white comprises of the entire visible color spectrum.  Anyone with decreased sensitivity to any particular color can have the rest of the color spectrum to rely on.

The most common color blindness is red-green (8% of male, 0.5% female for Northern European descent according to Wikipedia), next to that is blue-yellow.  Yellow, orange, amber are colors are a mix of red and green, so it is unfriendly to decreased sensitivity to red-green.  The traffic light colors are even less friendly to them, yet red-green insensitivity appears to be the most common.

It may not make any difference to most of us, but I guess only until someone runs over your dog because the street is lid with yellowish lamps.

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There's also a difference in sensitivity between photopic and scotopic vision, more bluish wavelengths have an advantage at low light levels. I think the real issue though is that so many things absorb orange light which leads to the effect of a bright source spraying light everywhere but the scene is not really lit up very well. The source itself looks very bright due to orange being close to the sensitivity peak of the eye but that just serves to drown out all the orange absorbing objects in the scene and produce a bunch of glare. There has also been a tendency to over-light, high light levels do not improve visibility over more modest levels, they just create contrast between brighter and darker areas. Modern regulations requiring full-cutoff luminaires that do not emit any light above 90 degrees also create a problem of needing more of them to create even illumination and even then you end up with bright pools under the source with dark spaces between. IMO they could achieve more effective lighting while still mitigating light pollution by using lower intensity sources and focus on providing even illumination. Less total light but more of it doing something useful.

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Most colour blind people don't have reduced sensitivity to red or green light, because they have the same number of red and green cones as everyone else. The difference is their red, or green, cones are a slightly different colour, than normal, which makes their colour perception different.

Is there anyone here old enough to remember gas street lights? My father is in his mid 70s and remembers seeing someone going round lighting the gas lamps every night, when he was a child.
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