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LED street lighting

Arran Cameron
My local council has replaced the high pressure sodium street lights that bathed the neighbourhood in a warm subtly yellow tinged glow with LED street lights that emit a piercing cool white light.


This is not the first change in street lighting during my lifetime. I'm old enough to remember when the monochromatic yellow low pressure sodium lights were commonplace in side streets and in residential areas before most were replaced by high pressure sodium lights – possibly in order to deter and reduce crime. However, mercury lights that illuminated cities with a weird greenish-white hue were a bit before my time. Where was the last place in Britain that used mercury street lights in large numbers? Was it Hartlepool? Before that were incandescent lights – a dimmer relative (in terms of colour) of the high pressure sodium lights.


The new LED street lights are certainly brighter than the old high pressure sodium lights, but it's a brightness that takes getting used to. The long term consequences of LED street lights remains to be seen. Cool white light has a colour spectrum containing plenty of blue whereas the old high pressure sodium light is shifted more towards the red end of the colour spectrum. I have read that blue light is bad for sleep whereas red light is good for sleep. Could cool white LED street lights end up causing insomnia? Are warm white LEDs a better choice for residential areas?


What do you think?
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    Until I was about 10, all the streets were I lived at the time were lit by gas! Very attractive mix of 2 or 4 mantles with a clockwork lighting mechanism. The lighting operative had to climb each pole to reset the clock, and a cast iron cross member was there for his ladder.

    The replacement strategy really interested me at the time. First they came along and put a concrete post next to each gas lamp standard. Weeks passed before a luminaire was added, and these were neat circular devices that looked like oversize standard lamps for the home. Weeks passed and suddenly they were switched on and the four sided gas luminaires were removed.

    The gas standards remained in place for a while, and the council eventually made a fortune selling them off to the public, typically for garden lighting. They were very attractive cast iron objects, cast in 1894 (the date was on the side - strange what you remember!).

    The 1960's concrete posts are still in place but with an incongruous mix and match of "sticky out" luminaires. No beauty any more. the light from the LED's is horrible (Gas was beautiful).

    Can you tell I'm getting mature! :)
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    The thing that finished the gas lights on Cottingham station (East Yorks) was the arrival of North Sea gas and the closure of the old Gas and Coke works, in about 1972 - I reckon without that it would stand  a good chance of still being gas lit today.


    I recall the off-white mercury street lamps as predecessors of the sodium yellow, as the street I lived in ( Essex)  and all the housiing estate around them, had them from before we moved there (early 1970s) to about 1983-ish.
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    A single 100W incandescent lamp every hundred yards or so in my youth. Surprisingly difficult to hit with a stone propelled by hand or catapult, or even an air rifle apparently ? Not a problem with so few cars headlights to ruin your night vision and the zig-zag pattern most followed when walking home at night wouldn’t have been influenced much by streetlights anyway?.  


    On a more serious note the new LEDs where I live nowadays are more directional, like spot lights, but they go off at midnight so some householders like me leave their outside lights on anyway. Mine are also LED so the cost is pennies and the street looks "classier".



  • 0
    When the council announced that they were going to replace all the low pressure sodium lamps in my town with LEDs, I was initially sceptical.  I had seen what happened when the high pressure ones were installed on residential streets.  Each new lamp would emit a bright light downwards only, giving pools of light and inky blackness in between.  They may have been good on the tall posts used on main roads, but on the short posts, they were useless.


    However, the new LED ones they used here seem to have been designed to diffuse the light out better, producing a spread of light up and down the road.  They actually work rather well.


    I was hoping for a darker bedroom at night.  But there's a lamp that's higher up the hill from my house, and it still shines through the curtains.


    There's also a bonus of the new lights that if I want to watch meteorite showers now, I can just go out into the garden.  A few years ago, all I would have seen was an orange glow in the sky.  That's gone now.
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    I think all the LED street lights that I have seen are too 'white'. When driving at night and approaching a junction the spillage of white light onto the road in front of you was an indication that another vehicle was also heading that way, a useful warning. Now all these LED lit junctions trigger my internal alert system! Some might say that is a good thing if it makes us cautious but of course eventually the sense is dulled until one night there is a vehicle there and we find out too late.


    In theory LED lights could be made just about any colour so why couldn't they be a bit warmer? As to the spread of light, the old light opposite my house allowed me to see enough to reverse onto my drive whereas the LED replacement doesn't.


    Considering the use of LEDs for illumination in general, whatever happened to concerns about glare? No attempt seems to be made to diffuse the light from these LED panels, they look like multiple bare filaments, something that would have been thought poor design when using incandescent lamps. Is it because the first LEDs used for lighting struggled to put out enough light so the loss in a diffuser would have been too much? But then people use GU10 Halogen Spotlight lamps to add 'sparkle' (or glare as it used to be called!).
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    James Shaw:

    I think all the LED street lights that I have seen are too 'white'. When driving at night and approaching a junction the spillage of white light onto the road in front of you was an indication that another vehicle was also heading that way, a useful warning. Now all these LED lit junctions trigger my internal alert system! Some might say that is a good thing if it makes us cautious but of course eventually the sense is dulled until one night there is a vehicle there and we find out too late.


    In theory LED lights could be made just about any colour so why couldn't they be a bit warmer? As to the spread of light, the old light opposite my house allowed me to see enough to reverse onto my drive whereas the LED replacement doesn't.


    Considering the use of LEDs for illumination in general, whatever happened to concerns about glare? No attempt seems to be made to diffuse the light from these LED panels, they look like multiple bare filaments, something that would have been thought poor design when using incandescent lamps. Is it because the first LEDs used for lighting struggled to put out enough light so the loss in a diffuser would have been too much? But then people use GU10 Halogen Spotlight lamps to add 'sparkle' (or glare as it used to be called!).




    You make some valid points about LED lights. I have thought about whether they should be warm white rather than cool white in residential areas as there is a British preference towards warm white for use in homes. Glare is also an issue and most domestic LED bulbs have a pearl finish with clear bulbs generally only used in chandaliers with lots dangling glass.


    Does anybody have much experience of the old mercury street lights for comparison?

  • 0
    The mercury lamps were still in use in residential streets in Surrey, when I was younger.  I remember them being a bluish white, when compared to ordinary incandescent lamps.  Definitely not "warm white".  The lamps were a bit bigger than domestic filament lamps, and enclosed in a faceted glass shade.


    Perhaps more glare than low-pressure sodium, but not excessive.
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    Simon Barker:

    The mercury lamps were still in use in residential streets in Surrey, when I was younger.  I remember them being a bluish white, when compared to ordinary incandescent lamps.  Definitely not "warm white".  The lamps were a bit bigger than domestic filament lamps, and enclosed in a faceted glass shade.


    Perhaps more glare than low-pressure sodium, but not excessive.




    Was that in the early 1980s?


    A friend told me that back in the early 1980s when he was quite young he visited Surrey and one of the towns (it could have been Reigate) had mercury street lights that emitted a light that he found to have an unpleasant hue and hard on the eyes. He was used to the yellow low pressure sodium lights at the time.



     

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