So i know of the Sulfur lighting and LEP lighting that people have talked about in the past... but are these technologies even able to take off? or is LED pretty well beaten them down?

I'm no expert, but LEP looks like it could have some impact on the market as there a few manufacturers out there. With how prevalent and cheap LED is, it's anybody's guess how successful it will be.

Personally I like induction as an LED alternative as the glare is much lower. However, it seems that a buzzword for many LED (and LEP for that matter) manufacturers is "optical efficiency". They talk about how much more "efficient" they are from optical precision and such. Thats all fine and dandy if you know what you are doing during design and install, but many installs I've seen in the wild are done improperly and very unevenly lit because of this. For example, when georgia power replaced all the HPS DG cobraheads in my parents neighborhood, they did a 1:1 replacement. The problem with that is the new cooper verdeons are full cutoff and have a very limited illumination area vs. "inefficient" DG cobraheads and now there is as many dark spots as light. They would've needed to double the density to get the same coverage. I personally think some "optical inefficiency" covers some laziness on the part of the engineers, not to mention reduces glare.

I doubt LEP will gain much traction, the cost of running, and the life of the magnetrons may not be deemed worth it for large scale use?, as for induction, well at the end of the day their just fancy compact fluorescent lamps, and electrodeless or not, you will still only get the same efficiency of a large scale CFL!
We have very few induction systems where I am, (mostly confined to car park lighting), and the silly price of the lamps I think would put most people off from using them.

Personally I like induction as an LED alternative as the glare is much lower. However, it seems that a buzzword for many LED (and LEP for that matter) manufacturers is "optical efficiency". They talk about how much more "efficient" they are from optical precision and such. Thats all fine and dandy if you know what you are doing during design and install, but many installs I've seen in the wild are done improperly and very unevenly lit because of this. For example, when georgia power replaced all the HPS DG cobraheads in my parents neighborhood, they did a 1:1 replacement. The problem with that is the new cooper verdeons are full cutoff and have a very limited illumination area vs. "inefficient" DG cobraheads and now there is as many dark spots as light. They would've needed to double the density to get the same coverage. I personally think some "optical inefficiency" covers some laziness on the part of the engineers, not to mention reduces glare.

It have nothing to do with uniformity. Its glare and spectrum



Our vision is capable of seeing well under very non uniform ligthing conditions. In daytime, an area under direct Sun light is about 100K Lux, and an area in the shadows is about 1K Lux. There is 100x non uniformity between the areas. We look at the scene with both areas in view, and see everything great at the same time - without having to "get used to" the light or the darkness. (That happens when the difference is way higher, on the order of 1000x+)

This capability scales down well all the way to the single Luxes level and below

So saying that a road with some "5x non uniformity in light levels" is poorly lit is ridiculous. At something like 2x you won't even see it unless you look specifically to spot it

yet one thing that LED tries to achieve is perfect uniformity...



Much of the "optical efficiency" thing is not so much about efficiency :

Intuitively we would consider any light that ends up on the road as light that ended up where we want it, so not part of the losses

When using the "uniformity is very important" logic however, if for example a road is lit at light level X (say 10 Lux) in the darkest point between lanterns, and 4X (say 40 Lux) in the brightest point under one lantern, then 30 Lux out of the 40 Lux at that point would be considered as losses too. A lantern that lights up the road with about the same light but more uniformly would be WAY more efficeint according to this logic



The "perfect uniformity" comes at a price :

 - To direct the light to the darkest point between lanterns, it have to be thrown at wide angle. When you go somewhat past this point the same beam is at your eye level, the lantern is in view, and is VERY glary

 - The optics that achieve such uniformity are lens panels, which do nothing at all to diffuse the light. Much to the contrary, to direct light in this direction, each lens focuses the light from its source to this direction

On the promotional materials (aerial photos of "see how well it is lit") this looks magic, but in reality, its down to :

 - A non perfect world in which you are empowered, in this case to see well using your natural capabilities

 - A perfect world in which you are powerless



Another point :

If we would light up the roads just enough to see what is there, we would need very little light. The roads would still look dark. The reason why we over illuminate roads to several times that brightness is so they look "welcoming", "safe" (psychologically) and so on

And for the "welcoming" etc, every light that is on the road counts. If we take our example road with 10 Lux in the darkest point and 40 Lux under the lantern, the "extra 30 Lux" while they maybe dont formally add to the required minimum light level, they do add to the lit appearance of the road. Also, they in fact do make the road brighter lit on average. Definitely not losses



Finally there is the spectrum. Apart of long term health effects, LED light nukes night vision right away. So the Lumens (and Luxes, which are defined strictly through Lumens and geometric optics) might be the same as with some other light source, but they are in fact worth much less in terms of visibility

It have nothing to do with uniformity. Its glare and spectrum



Our vision is capable of seeing well under very non uniform ligthing conditions. In daytime, an area under direct Sun light is about 100K Lux, and an area in the shadows is about 1K Lux. There is 100x non uniformity between the areas. We look at the scene with both areas in view, and see everything great at the same time - without having to "get used to" the light or the darkness. (That happens when the difference is way higher, on the order of 1000x+)

This capability scales down well all the way to the single Luxes level and below

So saying that a road with some "5x non uniformity in light levels" is poorly lit is ridiculous. At something like 2x you won't even see it unless you look specifically to spot it

yet one thing that LED tries to achieve is perfect uniformity...



Much of the "optical efficiency" thing is not so much about efficiency :

Intuitively we would consider any light that ends up on the road as light that ended up where we want it, so not part of the losses

When using the "uniformity is very important" logic however, if for example a road is lit at light level X (say 10 Lux) in the darkest point between lanterns, and 4X (say 40 Lux) in the brightest point under one lantern, then 30 Lux out of the 40 Lux at that point would be considered as losses too. A lantern that lights up the road with about the same light but more uniformly would be WAY more efficeint according to this logic



The "perfect uniformity" comes at a price :

 - To direct the light to the darkest point between lanterns, it have to be thrown at wide angle. When you go somewhat past this point the same beam is at your eye level, the lantern is in view, and is VERY glary

 - The optics that achieve such uniformity are lens panels, which do nothing at all to diffuse the light. Much to the contrary, to direct light in this direction, each lens focuses the light from its source to this direction

On the promotional materials (aerial photos of "see how well it is lit") this looks magic, but in reality, its down to :

 - A non perfect world in which you are empowered, in this case to see well using your natural capabilities

 - A perfect world in which you are powerless



Another point :

If we would light up the roads just enough to see what is there, we would need very little light. The roads would still look dark. The reason why we over illuminate roads to several times that brightness is so they look "welcoming", "safe" (psychologically) and so on

And for the "welcoming" etc, every light that is on the road counts. If we take our example road with 10 Lux in the darkest point and 40 Lux under the lantern, the "extra 30 Lux" while they maybe dont formally add to the required minimum light level, they do add to the lit appearance of the road. Also, they in fact do make the road brighter lit on average. Definitely not losses



Finally there is the spectrum. Apart of long term health effects, LED light nukes night vision right away. So the Lumens (and Luxes, which are defined strictly through Lumens and geometric optics) might be the same as with some other light source, but they are in fact worth much less in terms of visibility

Excellent observations Ash. It seems that what was done previously to light the roads using HPS used lanterns that produced a wide even light that produced lots of glare. However the nature of HPS light in my experience doesn't seem reduce night vision as much or painful to look at, which seems to mitigate some of the negative effects of glare and light trespass to an extent. Therefore, if LED replacement lanterns were fitted that had the same optical characteristics, one would most likely have to wear a dark pair of sunglasses to be able to drive.

I guess to home in on my first point was to say I don't consider taking a evenly and well lit neighborhood, road, etc. and replacing the fixtures with something that produces a splotchy, mostly dark result as an improvement. Regardless of what light source lit the place originally. Which has now taken the thread off subject, sorry.

The LED allow the spectrum to be designed whatever is wanted. That is big difference towards any high pressure arc (LEP) or to big extend to the fuorescent.
The reason, why many LEDs have so awful spectrum is just because they are intended to have it like that (the best figures of CRI and efficacy according to standardized tests). Most LED makers do offer LEDs with very good color (really good, not steered by just the standardized rating figures), the market is appreciating that, therefore the market price of these types is still rather high even when their efficacy and CRI figures do not look that great (compare to their cheap counterparts).

So when someone asks a cheapest LED's with "excellent performance figures", you should not be too surprised the makers will come with a design optimized for the CRI figures alone (so to get seemingly good figures even with an older, less performing but cheaper technology) and not regarding the side effect not covered by the standardized parameters.

And because for many applications the color quality is not the top priority (e.g. the street lights), the resulting color quality is only as good, as possible without need for sacrifice of the other parameters (mainly efficacy and cost).