LED streetlights beneficial to light pollution?!

[Astronomist]

Over the past two years or so I have noticed that sky has appeared noticeably darker each year, with far more of the milky way visible. Over the same time period the local council has replaced all the sodium vapour streetlights in and around Salisbury with the horribly bright LED variety. I suspect that this is attributable to the design of the new lights, which directs most of the light downwards, in contrast to the old ones which allowed much of the light to spill out of the sides. Has anyone else noticed this, or is it just me imagining things?

[Jim Franklin]

5 minutes ago, Astronomist said:

Over the past two years or so I have noticed that sky has appeared noticeably darker each year, with far more of the milky way visible. Over the same time period the local council has replaced all the sodium vapour streetlights in and around Salisbury with the horribly bright LED variety. I suspect that this is attributable to the design of the new lights, which directs most of the light downwards, in contrast to the old ones which allowed much of the light to spill out of the sides. Has anyone else noticed this, or is it just me imagining things?

If they are a well designed fitting then you are correct, little light will escape and they will have been placed at a height that reduces reflections, Salisbury Council may well have done it properly - They introduced these in Swindon in 2018 when i was still there, the light pollution become a bigger issue as they have installed "daylight" street lights that are a cheap design - about 10% of their light goes skyward and a lot more just vanishes into the environment. 

I'm all for LED lighting, but I think they should all be designed to a very tight standard and all street lights should have motion detectors on them so they only light up when a person is on the pavememnt - they do not need to light the road - its why cars have lights!!

[Louis D]

In my case, skies used to yellow-orange around my house due to sodium vapor lighting.  It was easy enough to filter that out with a UHC filter.  Now, my skies are uniformly gray, and the UHC doesn't help nearly as much as it used to.

[Jim Franklin]

1 minute ago, Louis D said:

In my case, skies used to yellow-orange around my house due to sodium vapor lighting.  It was easy enough to filter that out with a UHC filter.  Now, my skies are uniformly gray, and the UHC doesn't help nearly as much as it used to.

Try a moon filter, in some instances these work for LED wastage, also, if you have one, a polorising filter can block some to - but my best choice in heavy LEDE areas with bad lights is a variable ND filter so I can tailor it to the light pollution...doesn't work everywhere and not for imaging, but for visual it does the trick on most objects. 

[Louis D]

Being that I live on the outskirts of a rapidly growing city, I've gone from being able to see the Milky Way 30 years ago to not being able to see most constellations today.  Had sodium vapor remained the preferred lighting, I could have at least filtered that out.

Edited August 27 by Louis D

[Louis D]

1 minute ago, Jim Franklin said:

Try a moon filter, in some instances these work for LED wastage, also, if you have one, a polorising filter can block some to - but my best choice in heavy LEDE areas with bad lights is a variable ND filter so I can tailor it to the light pollution...doesn't work everywhere and not for imaging, but for visual it does the trick on most objects. 

I have multiple ND and variable polarizing filters, so I'll have to give that a try sometime.

I did find using an X1 or X0 Green/Yellow-Green photographic filter can make for a decent poor man's UHC filter on bright nebula like the Orion Nebula by cutting light not in the blue-green part of the spectrum.  While the nebula got a bit dimmer, the skyglow got noticeably dimmer.

[Louis D]

Back to OP's point, I suppose if you live an area of constant number of outdoor lights, it is possible that well shaded LED lights might outperform older, unshaded sodium vapor lighting.

[globular]

Skies are lighter and lighter year on year to my eyes in my location.

For every streetlight that has been changed to LED there are numerous houses around it that have added their own lighting up their façade / up their trees / along their fences; some just for a few hours into the evening, but most all night long on dust 'till dawn sensors.  And the ever expanding housing and industrial estates adding lights where previously there were none. 

It would have been worse if councils hadn't done something about street lighting; so good on them for that - but something needs to be done about light pollution from non streetlight sources too if we're ever going to darken our skies.

And that's the rub - councils are moving to LED primarily to save money on powering the lights, not to darken skies.  So they are not interested in doing anything else, because that will costs money not save it.

 

Edited August 27 by globular

[Elp]

The thing about led lights, I don't think they propagate as far as older ones, so in terms of providing "better" illumination, they only illuminate within a narrow cone. To me, the streets (under the lighting) are bright directly under lampposts, but otherwise darker as you move away from them. I've seen this on a road which had LEDs on one side, and old ones on the other, the older side was way more illuminated. Comparing car headlights you get the same, the older lights went further, struggle to see any distance forward with LED headlights which is starkly seen when there's no streetlight around, and worse they dazzle far more when facing them, something powers that be have seemingly chosen to ignore.

[Elp]

5 minutes ago, globular said:

houses

There should be a height restriction law. Some, dimwit two houses down (so two gardens away) has decided to place not one, but TWO "security" lights at second storey level, I can activate them from my garden, complete utter unmentionable.

[Elp]

Also, the industrial spaces dont seem to care. LED skyglow beaming all around me when looking up, when it's overcast it's bright.

[globular]

Councils did almost nothing about increasing recycling take up for years and years. They are now charged / fined by the weight of landfill waste produced in their area. So councils now do a lot to promote and even force residents to recycle more / sort their waste.  Thank goodness.

Introduce a council fine for the light glow in their area and the council will miraculously start doing something about unnecessary residential and industrial lighting.

Globular for president! 🤣

[Cornelius Varley]

Some posts have been removed. Posts suggesting illegal activities, even as a joke, will be removed.

[Mr Spock]

Since the introduction of LED lighting my LP has taken a nose dive. 

I used to have an orange sky to the east and clear to the west. Now it's uniform light grey all over. I used to be able to see the milky way and M31. Now I can barely see below mag 4 on most nights - occasionally 4.5 if transparency is good.

[Astronomist]

1 hour ago, Jim Franklin said:

Salisbury Council may well have done it properly

There's a first time for everything I suppose!

 

[ELS]

I'm more a fan of the old LPS lamps, not HPS which are what you're probably thinking of.
LPS had a very narrow spectrum, so you could just filter them out. Also they maintained the night vision of your eyes, so it didn't take 10+ minutes every time you drove through a city to get your night vision back.
Animals also minded them less.

[Zermelo]

Two factors that can be important :

- simple retro-fitting of LEDs into old sodium fixtures can result in a lot of light spilling horizontally or even upwards. If the fixture design itself doesn't constrain the light, then the LED unit needs to

- even if the LED light is directed downwards, many are just too bright, resulting in a significant amount reflected up from the ground

[Astronomist]

Here is a picture of one of the new fixtures:

The bulb (is it called a bulb with an LED?) is recessed inside the housing so no light can leave unless it's going downwards-ish.

A quick google search indicates that these might in fact be 'light pollution reducing' fixtures. Kudos to salisbury council if this is the case! 

 

[Carbon Brush]

In the time in my current home, street lighting has gone/progressed (modify as appropriate) from low pressure orange sodium, to high ressure sodium, to LED.
Here is my observation - which is not necessarily valid for other locations.

The original low pressure sodium lights extended over the road. Keeping the light fittings out of the trees.
Later fittings had the light source almost on top of the poles.
Many lights are in the trees and pavements are darkened. Thank you hyper-intelligent street light people.

Original low pressure sodium had poor spread. By that I mean it seemed to go everywhere.
But is was easily filtered.

When we were 'upgraded' to high pressure sodium, it was till a poorly controlled (shine anywhere) type.
It was much brighter than the original. However, filtering was now all but impossible.
The hyper-intelligent street light organisers didn't seem to realise they could have fitted the new posts further apart, rather than planting in the same holes.

I groaned when I saw LED lighting being installed. However, I am seeing benefits.
The lights shine down and have good cut off.
My back garden is now darker, even though I can now go on the street to read a book.
Many of the lights still shine in the tree canopy!
It has not occurred to the lighting folks that the trees are here to stay (in a preservation area) so they ought to be planting lamp posts away from trees.

So actually by accident, rather than by design, the situation in my village has improved.

 

Edited August 28 by Carbon Brush

[Tony Acorn]

13 hours ago, globular said:

Councils did almost nothing about increasing recycling take up for years and years. They are now charged / fined by the weight of landfill waste produced in their area. So councils now do a lot to promote and even force residents to recycle more / sort their waste.  Thank goodness.

Introduce a council fine for the light glow in their area and the council will miraculously start doing something about unnecessary residential and industrial lighting.

Globular for president! 🤣

Suggesting that local bureaucracy should be increased to address light pollution is an anathema to me because Councils, Councillors and their employees are people living in a rarified environment, dreaming of how extend their little empires, impliment another layer of control on the residents / businesses who believe that these people / companies will continue to pay even more to support schemes - many of which are hair-brained in the first place!

We also live in an age where residents will form a vociferous body to oppose any reduction in street lighting levels or operating times on the basis of "security" which could and perhaps should be resolved through more effective policing and a justice system that offers real deterrents. In order to trim our costs, our local council (and I was part of this) wanted to cut the street lighting between 01:00 and 05:00, saving significantly on the energy bills even after installing the necessary timers. A few (and it could be measured in 10's rather than hundreds) started a campaign bombarding the council leader, their local councillors and even their MP with their opposition - arguing that women and children walking the streets after 01:00 wouldn't be safe.

Having had a decade of involvement at local and county council levels, I think I can speak with reality (the example above) born of experience.

Tony

[Carbon Brush]

It is interesting to consider that  when I started driving in the 1970s, lighting was very different.

Many villages still used mercury lights that gave a dim pool under the post and darkness between posts.
I remember a small village near Barnsley still had a road or two with gas lights!
When you went to a big town, they had sodium lights.

While on sodium light roads, many drivers ran on sidelights to conserve power in dynamo (rather than alternator) equipped cars and to help bulb life.
Many cars used a standard circular Lucas headlamp. Nowadays seen on Morris Minors and the like.
These gave awful scattered light compared to the lighting we have nowadays.

We used to accept that road lighting was patchy and day/night driving speeds differed.

An alternative view from about 1975. I was speaking with someone about night driving.
It turned this person, with about 5 years of driving experience, had never driven on an unlit road.
He lived and worked in the London area.
 

[StevieDvd]

I had a  mini 850 that I had 'upgraded'  with electronic distributor and halogen headlights, as well as many repaints/resprays.  My elder brother had a Vauxhall Viva and asked me to come and collect another car so I was tasked with driving his viva home. When in the drivers seat I asked why he only had sidelights working as the road was so dim. His headlights were on, I was just used to having 'proper' lights.  Driving around it was common for other drivers to shout that I had main beam on, which I had not. So turning them on gave let the 'brighter' ones realise they had been dipped!

 

[Jim Franklin]

6 hours ago, Astronomist said:

Here is a picture of one of the new fixtures:

 

The bulb (is it called a bulb with an LED?) is recessed inside the housing so no light can leave unless it's going downwards-ish.

 

 

It was never a bulb - they go in the ground and grow in spring - LAMPS go in light fittings 😂 (I know - typical engineer!!)

[Carbon Brush]

@Jim Franklin & @Astronomist
The incandescent lamps innards comprised the wire filament & supports.
The outside glass thingy was called the ENVELOPE.
Ready now for comments from members knowledgeable in stationery provision😅

The incandescent (filament) lamp was always difficult to direct as it had a large filament that radiated in all directions.
The discharge (sodium or mercury) lamp was more problematic as the light radiated (sort of) uniformly from all of the large glass envelope.
Any effective reflector therefore had to be very large compared to the 'light generator'. With large comes heavy and expensive.

Move on to the LED (or even a cluster). LED lights are much smaller than 'bulbs' for a given light output.
In addition, at manufacture the innards are made to produce light in one direction only - nothing comes out of the back.
Further, integrating a lens into an LED means you can chose a narrow or wide radiating angle.
The end result is that you can make a small light source with known radiating angle, easing reflector design.

Another benefit of LED is that it is easily controlled from 100% to 0% brightness. Dim if full power not needed in this location - radical idea.
Then of course, it works immediately on power up - unlike sodium lights. Bringing up the idea of pedestrian/traffic motion triggering.
By mixing the LED ingredients (big subject) you can adjust the 'colour temperature' or appearance.

So you take this wonderful, almost ideal, light source. You can put exactly the required light in exactly the right places and only when required.

Next apply a generous portion of council policy makers, council fitters, and muggle residents.
We end up with lights shining into bedrooms and gardens, Sometimes into the distance well away from roads.
Residents (not just astro types) request shields.

Then because it is 24/7 daylight in your village/town streets, you cannot see to walk anywhere out of the bright region, so ask the council to extend it!
Every alleyway, footpath, empty park and more gets additional lighting.

[ScouseSpaceCadet]

On 28/08/2024 at 09:29, Astronomist said:

Here is a picture of one of the new fixtures:

The bulb (is it called a bulb with an LED?) is recessed inside the housing so no light can leave unless it's going downwards-ish.

A quick google search indicates that these might in fact be 'light pollution reducing' fixtures. Kudos to salisbury council if this is the case! 

 

They're supposed to reduce light pollution, however that's not much use if you're surrounded by the things shining in your face and reflecting off neighbours' windows. 🙄