I think the main reason is that of redundancy - if the bulb goes in a traditional light then the light doesn't work at all. Since there are multiple LEDs then if one goes it's only a fraction of the light output gone.
As for light pollution - that will be more due to the direction the light is pointing (hopefully downwards) and the diffraction effect given by the cover.
I have these in my street, and I have to say they are no where near as good as the old (perfectly functional) lights. I understand the need to save power, but I can't understand why they couldn't just change the heads rather than ripping the whole thing out of the ground and replacing it - seems like a lot of money spent unnecessarily.
The main problem with them is the quality of the light, and the "whiteness" of the light - somehow it seems to be dimmer where the light is meant to be (on the street), yet brighter in my house where I don't want it!
In Milton Keynes they are installing them, and they are just replacing the heads.
I think we "over-light" our streets in the UK. I've seen LED and fluorescent fittings in other countries that just provide a usable background light - we seem to think it should be daylight 24/7, which is a waste of money.
> I can't understand why they couldn't just change the heads rather than ripping the whole thing out of the ground and replacing it - seems like a lot of money spent unnecessarily.
Lamp posts corrode, they have a finite service life. Yours may not yet have been unsafe but they may well have required replacement within the life expectancy of the new lamps being fitting. Doing the job once saves money. Equally it may be that adapting new heads to several different post designs across the town is significantly costlier than simply replacing the (consumable) posts. Write to your council and ask them if you're genuinely interested.
In reply to jkarran:
Yea here in Blackpool the old ones were concrete posts and no doubt they have suffered internal contrete cancer and were time expired even though they look sound. The new ones the Lemming refers to are shiney steel ones and the one outside my house was replaced about 3 weeks ago. It terms of light output they seem to give a much brighter light, glad we don't sleep in the front bedroom. I think I'll be able to service the car on the drive during night time now.
> (In reply to balmybaldwin)
> I think we "over-light" our streets in the UK. I've seen LED and fluorescent fittings in other countries that just provide a usable background light - we seem to think it should be daylight 24/7, which is a waste of money.
But "over-light" is handy for running at night without a headtorch, on that basis i'm starting a petition to prevent further rollout of LED street lamps.
Maybe it's not as harmful as chemical pollution, but it is one of those things that makes life a little bit worse for people. Add enough of them together and you have a good argument for gassing all the cities
In reply to The Lemming:
I think it's quite easy to collimate LED light output - this means the light will be focussed downwards rather than being emitted in all directions. You can contro, where the ligt falls much more readily. The electricity savings should be huge, but the initial costs are much higher. They should also last a lot longer.
There should be less light pollution if designed properly!
In reply to The Lemming: The council replaced ours last year and actually used sime sense. They altered the spacing and as a result we now have 2 posts in place of 3 and the street is still lit adequately.
> The main problem with them is the quality of the light, and the "whiteness" of the light - somehow it seems to be dimmer where the light is meant to be (on the street), yet brighter in my house where I don't want it!
I note a light near where I live has a little shield that stops it shining into the adjacent house. Maybe you should complain to the council?
In reply to Neil Williams: Perhaps, but most of the light seems to fall on the road and not in people's windows... unlike the old light which is shining directly into the camera and reflecting in one of the windows opposite.
True, though the bright white light is quite hard on the eye and would make it quite hard to sleep as it reflects off the road, while the yellow is far more restful.
Just because LED is low-energy doesn't mean we should be burning money - a very low light, just enough to ensure there are no dark corners, directed at the road and pavement should suffice to save money and to reduce light pollution.
> Just because LED is low-energy doesn't mean we should be burning money - a very low light, just enough to ensure there are no dark corners, directed at the road and pavement should suffice to save money and to reduce light pollution.
Fair dos. Street lighting is a bit of an odd one really. Since it is not metered, no one really knows how much it actually costs. It is just an estimate. Whether LED lighting is really answer is probably anyone's guess although personally, I do like the directional element of it. We have just had a light put up nearby that lights the area within several hundred metres which is a bit of arse given that without it, my garden would be just dark enough to do a bit of suburban star gazing. As it is, there is no chance.
In reply to The Lemming:
They changed the lights in Nottingham and the new lights are really bright and seem to be very wide angled without much of a reflector to direct the light.
The very white light seems to destroy any night vision you acquire so the shadows seem darker.
I can see the councils liking the lifespan of the LED units, fewer lamps to change.
Remember that Human eye is pretty 'clever' and generally works much better at equalising light levels etc - while a camera tends to be a bit more 'true' as far as showing exactly how much light there is.
It's a good point about the direction in my picture, looking at it - you can see that the sides of the houses at the end of the street look brighter. While with the LED light there is a very clear cut-off, where it's noticeably darker after on the lawns.
Whether having defined bright areas giving relatively darker shadows is a good thing is another matter when 'safety' etc is concerned.
> (In reply to Neil Williams)
> Agreed, how light do we actually need it to be?! So long as I can vaguely see where I am going then thats fine by me.
I heard a debate on the parliamentary channel ( I have trouble sleeping) where some councils had switched off most of the street lights to save money. Apparently there was no statistically significant rise in criminality or accidents!
(Unless you call Dogging criminal)
> (In reply to The Lemming)
> The very white light seems to destroy any night vision you acquire so the shadows seem darker.
There seems to be a brighter is better mentality when it comes to lighting. The new high intensity headlights are an absolute menace to oncoming traffic, dazzlingly bright and completely destroy night vision leaving you almost blind on unlit roads.
In reply to The Lemming: I've never really understood the design of street lights. They are all designed to hang or lean over the road. Yet all cars have lights? Lighting the pavements would be much more sensible which would require posts of only a metre high throwing light on the pavements.
One stretch of dual carriageway by me has so many lights you could land a plane on it, yet as you cross into the next borough, there is no lighting at all. Why would you need it? No pedestrians should be walking along there.
In reply to itsThere:
Different ones to the ones in Reading, but makes sense that they'd have that ability.
Would seem to make sense to maybe turn them down a bit after midnight and a bit later on weekends of something.
Personally, I do find it much more pleasant driving on a properly lit motorway or A-Road. Even more so when on a motorbike and most definitely when on a push bike (though wouldn't really go near a fast dual carriageway on a push bike at night given the choice.)
In reply to needvert: For low power (headtorch) LED is the way to go if you do it right. for high power they have reached a cross-over point, i would gess that the lifetime of an LED has swayed the council into new LED lights. I dont know the figures to back this up.
Sodium lighting was brought in the 70's during the last UK oil crisis. The lighting was white before then. This is just the next stage in energy saving and makes sense. LEd's have been replacing the old lighting systems most other places and use significantly less power for the same light output
We were told that when they changed ours, they also said they would turn half the lights off in the wee hours, but they haven't yet and weve had them nearly 2 years. Regardless of them being more directional, the whiteness of the light seems to mean more light reflects into the front bedroom, which means even with thicker curtains it effects sleep. Luckily its just my spare room.
Quite possibly - most street lights would have had lamps <100W, and it's plausible that the LEDs are of a similar order of magnitude. But; low pressure sodium lamps have been getting increasingly hard to obtain and therefore more expensive. I've also got a feeling they're particularly bad for the environment, although i'm not certain about that. Of course the reduced maintenance costs is a major factor as well.
"Incidentally daylight is beyond cool white in the spectrum, but daylight bulbs are usually pretty expensive"
Full spectrum ones yes, but daylight "blue" ones are becoming annoyingly common. They do my head in, because my brain doesn't expect daylight without normal shadows etc, nor for it to be slightly dimmed compared with real daylight.
First Great Western and WH Smith are prolific users of the evil things.
FWIW, my house is now 100% LED GU10 spots, the tenner-a-go Philips ones which provide an excellent light quality and no discernible flicker.
I suspect I have low persistence of vision, though, as I find almost all cheap ones have a visible flicker. Same with all car tail light ones I've seen, they are really irritating.
The latest annoyance is that the decent independent cafe outside Euston station on the left has installed daylight-temperature cheapo LED spotlights, which fail on both counts and may well put me off going there in future.
Sometimes they seem to go our or light up when you go past them (i.e. change state). I've long wondered why this was, I suspect it has to do with a dodgy connection combined with mobile phone interference, perhaps?