One example I was able to find of the spectral distribution of light from a white LED light showed a marked peak at around 453nm, but the spectrum was continuous.

This means it won't be easy to filter out, the way light from the previous energy efficiency champ, low-pressure sodium was (it's all in the D line).

Which means more light pollution for amateur astronomers who can't afford to drive into the country to observe.

Where I live LED traffic lights are the norm. They are almost indistinguishable from the usual ones.

Imagine, every street light able to be 'tuned' to its own specific colour, or cycled through a rainbow affect - every town could become a work of art, or you could spell the name of the town out for aircraft flying overhead. The colour could be tinged red if traffic is bad, or a slight hint of green if the roads are clear. They could be a lighter colour if somebody is walking nearby, dimming down again to reduce pollution once they have passed by...

I think I'll change my name to Ama Zon and submit a patent application...

Richard, I suspect the formulae look more like:

cost of replacing entire city's LEDS = $630k

(cost of replacing half of your sodium lights + cost of running sodium lights per year) - (cost of replacing one-sixth of city's LEDs + cost of running LEDs per year) = $100k

Nice to see it.

Reduced 'lit' times would be good too.

@Richard

The old lights weren't free.

Guess some of the extra might be made up in the fact that over the 4 years they are not ging to have to do 2 bulb replacements on the standar streetlamps.

@Richard Eustace: They replace the normal bulbs every two years, which means they will be factoring in the cost of two sets of normal bulb replacements into the break even point.

How ever their total savings per year should be $630k * 2.5 / 10 = $157,500 when you factor in the costs of replacing 3 more sets of none energy efficient bulbs.

The move is a good one but as someone else posted, why not turn them off? or how about this, a sensing network that only turns them on when someone is nearby?

The $100,000 is only the energy savings, it doesn't include money saved for having to change the lamps less often, less maintainence, etc

The government is doing something productive! Holy shit!

But it looks like smoke and mirrors to me

I'm not so sure that the reduction in maintenance will be as dramatic as expected. They really can't be thinking of not cleaning the light cover for ten years? LEDs are not that bright anyway, without needing to shine through a decade of grime.

One thing which did astonish me when traveling in the USA was the huge amount of illumination of traffic signs, rather than using signs made from reflective materials.

My recollection was that LEDs and fluorescent about equally efficient, i.e. both much more efficient than incandescent. Maybe technology has moved on since I last saw the numbers. Or, maybe the bulbs that they're replacing actually are incandescent bulbs! I mean, they're replacing them every two years; that doesn't sound like a fluorescent bulb to me.

Have you ever lived near a normal street light that was on the verge of giving up the ghost? They glow, then they come on bright for a while, then they snap off. Then they glow, then they come on bright for a while, then they snap off. It's damn annoying to the local residents. I don't imagine a sensing network would be any better.

Oh, and a big yay! for the LED street lights.

-daniel

New York installed them a couple of years ago, very fast rollout. Street lighting is still sodium-arc, though. Zero dent on light pollution; that's not exactly the point in this town. However, with the sheer quantity of traffic signals and pedestrian signals now sporting LEDs, there's got to be an enormous power savings, maintenance savings and huge kickbacks and political favors for such a large deployment. The icing on the cake- the new signals seem to work just fine.

I hope they are up to it.

Non-LED Flashing coat thanks.

"...and even Toronto" - what's that supposed to mean? Anyway, the City of Toronto kept incandescant street lighting until around ten years ago, because no one could stand the orange or pink sick look of the sodium lights used in the suburbs. Finally, when metal halide lamps got affordable and reliable enough, they made the move, and it's been pretty good. Each lamp takes 70 W, and the ballast takes 20 (which could presumably be improved on with modern electronic versions). The old incandescant bulbs were either 300 or 500 W, depending on the size of the street, so there's a pretty good saving. But they did insist on adding more lights (every pole has one now, where before there were often gaps), so the energy saving isn't what it could've been.

I think people are confusing LED street lighting with LED traffic (signal) lights, which are already quite common in Toronto and elsewhere. I don't think LED technology is bright enough for street lighting yet. But then why do we light streets in the first place? Why not light pedestrian areas with low-level, small lights, and leave the cars to fend for themselves, as they do on rural highways?

We've been having incandescent bulbs in traffic lights gradually replaced (all new installs are LED, older units are being replaced on both an as-needed and a scheduled basis.)

The LED lights are visible over better distances and the colour is sharper (especially when the green or red coating in the lens of the incandescent ones starts to age),and seem to be lasting quite well - some of the earlier units have been around for ages and are still running fine.

Could be those who're experiencing problems are encountering ones made to the cheapest possible specs by really shitty manufacturers.

We've got a newish intersection near an old one (they rerouted a few roads a while ago) and when both sets of lights are green during daylight hours I can see the more distant LED lamp more clearly than the old and faded incandescent on - both in amount of illumination (at night the LED is even more obviously brighter than the incandescent) and clarity of colour (vibrant green vs greenish tinge).

The incandescents seem to lack the light output (even with half the colour filter faded away) to be clearly visible during the day while the LEDs are very noticeable.

There is of course one problem that I, as a wearer of glasses with a hefty prescription, has found.

In the UK, with the pole-mounted traffic lights, there is little problem, but US19, just south of Atlanta, for instance, has a bit of a problem when it rains. The greens are very bright (I think Clayton county went for the ultrabrights) and as it's often windy when it rains, the traffic lights on the overhead wires sway back and forth. You can end up being dazzled at night not only by the traffic lights themselves, but by its reflection off the wet road as well. More htan once, I've had to have my wife act as a co-driver, to talk me off the road, having lost a good percentage of my vision do to this.

I'm also trying to think of any road signs around here that are lit up. I don't even think I20 and I75's signs are lit up, unlike the british motorway signs I remember so fondly. Then again, the whole state of Georgia has less electronic traffic signs than the M57.

The real WTF here is that an electric light has a carbon footprint. As and when this scandal is tackled, the green credentials of these new lights will be much reduced.

> What percentage of your CFL lamps last longer than 3 months?

100%. I bought my first one in about 1990 and it's still going; most of mine are about 12 years old and in perfect health. I have had only one failure in all that time.

> If the power supply doesn't blow up in the first month the wires

> usually break loose from thermal stress in the next month.

I think you got a bad batch. Did you complain to the retailer?

Back on topic: the more I think about this, the more convinced I am that these people in Ann Arbor are replacing _incandescent_ street lights with LEDs. They probably never adopted the sodium vapour lamps that the rest of the world uses because they don't like the colour. For those of use with sodium vapour street lighting, moving to LEDs would increase energy use.

"Gah! Imagine trying to get to sleep when the streetlamps outside your window keep going on and off..."

Haven't you anything else to do? Getting the 'other half' 'going on and off' a few times a night would want me gettin' some of those lamps.

Maybe because she's Finnish.....

</coat>

"Gah! Imagine trying to get to sleep when the streetlamps outside your window keep going on and off..."

Haven't you anything else to do? Getting the 'other half' 'going on and off' a few times a night would want me gettin' some of those lamps.

Maybe because she's Finnish.....

</coat>

If LED lighting was already that good I'd be able to light my rooms at home with them. As it is I can't even find a retailer willing to rate the light from an LED light source in terms of incandescent bulb equivalent power. Speaks volumes for the usefulness of today's LED lights.