My reference to blue-enriched is just a reference towards deliberately blue shifted white light. Don't be so sly. There are no studies showing any definitve improvement in real world driving conditions of higher CCT LEDs like 5000K over lower CCT light such as 3000K LED. Furthermore,
this study by UMTRI showed no improvement in driver seeing ability with higher color temperature lights. Additionally, research conducted
at the CLTC at UC Davis showed the same thing.
The first study failed to adjust for intensity. The blue tinted bulbs definitely had much lower output than the untinted bulb. Given that, I'm honestly surprised that the blue-tinted bulbs didn't perform
worse than the untinted ones. When you start comparing different CCT light sources, you need to have similar intensity AND CRI or the comparison is meaningless. Not sure what the CRI of the tinted bulbs was, but it was certainly well under the ~100 of the untinted one. I wonder how the blue-tinted bulbs would have performed without the handicaps of lower intensity and lower CRI.
The second study mentions the International Dark Sky Association and the American Medical Association. The former wants lower CCT and even possibly monochromatic outdoor lighting to benefit astronomers. It doesn't care whether or not this lighting is inferior for actually seeing things. The latter is concerned about blue light effects on the sleep cycle, except this is entirely irrelevant for outdoor lighting because people are typically exposed to greater intensity blue-light sources once they get home, and they go to sleep at least several hours after being exposed to streetlighting. By then any effects of blue light exposure have worn off.
With the research I linked above, higher color temperature lights do not provide any significant improvement in real world driving conditions. However, they do increase glare.
Glare is more a function of fixture or headlight design/aiming than anything else. The basic premise is to put the light where you need it, and cut it off where it isn't. Spectral content in the blue area is a secondary effect, but as I said you can have higher CCT with lower blue light content by going with higher CRI.
No, no it doesn't. The study you linked compared two extremes, spectrally deficient 2100K HPS and white MH. It did not show or quantify any improvement in seeing ability when comparing lower color temperature white light. In fact, as far as I can see, it didn't even quantify the "improvement" in seeing ability of MH. It also didn't mention the color temperature or SPD of the MH lamp.
You missed everything else in the study. Yes, in this case they compared HPS and MH simply because that's all that was available in terms of outdoor lighting when the study was originally done in the early 2000s. The major takeaways are as follows:
1) Higher CCT has higher apparent brightness for any given light intensity level
2) Higher CCT makes it easier to discern small details (relevant for driving if you want to see objects several blocks away)
3) Higher CCT results in greater peripheral vision (from the study:
However, in a simulated roadway application (no vehicles to run over the subjects!) where they tested peripheral vision, they found that the subjects had faster reaction times under MH than under HPS, all other conditions being equal.)
During EPIC-sponsored CLTC laboratory activities, a broad range of products between 2,200 K and 6,500 K has demonstrated that similar color rendering, discrimination, and visual acuity can be achieved.
Per what I wrote above that is only true only if the intensities are adjusted to compensate. I found this chart on my hard drive:
So in theory you can match a light source with lower blue content to give equivalent seeing by increasing the intensity, but by the time you do that the overall blue light flux will likely be the same as a higher CCT source (and you'll be wasting several times the power). If you keep intensities the same, you end up with lower apparent brightness, less ability to discern details, and most importantly far less peripheral seeing using a lower CCT light source.
I think your entire reason for starting this thread was a misinterpretation of JW Speaker's position. It sounds more to me like they're advocating against excessively blue, high CCT which provide no or negative improvement in seeing, rather than advocating going to 3000K or less for everything as you appear to want them to. The studies I've seen (and I've read lots of them) mostly point to 4000K to 5000K being the optimal point for headlights and streetlights. JW Speaker appears to be rallying against sources much over 5000K, and especially those which don't even appear white. There's a lot of junk on the market with an angry purple appearance. I agree these lights are more a fashion statement, and actually make seeing/glare worse. But the pure white ones which might be 4100K, 4500K, etc. are pretty much the sweet spot. They also happen to maximize energy efficiency, although that's a secondary concern for headlights.
And I remain convinced smoking in public spaces isn't a bad thing, but ultimately that and this aren't backed up by research. Obviously, I'm being sarcastic, but the point stands.
It sounds more like you're being dismissive of any research not supporting your desired conclusion, like the way you dismissed the entire part about peripheral vision favoring higher CCT sources.
I'm somewhat at odds with the outdoor lighting industry for different reasons, mostly having to do with their reluctance to even consider high-CRI lighting. However, if studies showed my reasoning on high-CRI outdoor lighting to be baseless, then I wouldn't pursue the matter any more.
