LEDs are becoming popular for headlights these days. The rules and regulations controlling these are not adequate for the new technology so manufacturers are taking advantage and producing headlights that are fundamentally unsafe.
The old tungsten headlamps that were used when these rules were written had a color temp of around 2700k. Halogen bulbs came out and were an improvement in light output and produced light in the 3000k spectrum.
DOT allowed the halogen bulbs even though they were a little brighter than original lights, but not really enough brighter to cause problems for people. Also the color temperatures were broad spectrum more or less centered around a color temperature. LEDs are narrow spectrum centered around their stated color temperature. Narrow spectrum concentrates the light energy on fewer of the cones and rods in our eyes, over stimulating them in comparison to a broad spectrum light of the same lumens and centered around the same color temperature.
Xenon lights became popular for awhile offering a brighter light that mostly a whiter light, higher color temperature.
Now comes LED bulbs that have a great deal of control over output, light pattern and color temperature. People tend to want the whiter light in their vehicles but don’t necessarily want other drivers, especially oncoming drivers to have them as they tend to blind them.
LEDs can be made to a wide variety of color temperatures, 2700k, 3000k, 4000k, 5000k and 6000k. The can also produce a lot more lumens per watt of any light source.
The 6000k not only blind oncoming drivers more than lower temp bulbs, they really don’t do much for the driver either due to curtain effect. Everything with in range of the bulbs does appear brighter, but that reflected brightness of close objects actually makes it harder to see objects a little further away. In bad weather, the problem gets much worse.
As an experiment, I put 6000k LED high beam lamps in my Silverado, left the halogens in the low beam. The LEDs pump out about 12,000 lumens, they are really bright. On low beam, I can see pretty far down the road, far enough to drive safely at 55 mph at night. When I flick on the high beams, every thing is brighter, but I noticed that it did not increase the distance I can see. It’s like the lights go so far and then just stop.
DOT needs to come up with a set of rules for headlights that do not consider the source of the light but just the specs of the light, such as output, color temp and pattern. Maybe even add the height above the ground, which will be tough on lifted vehicles, but lifted vehicles are a problem when it comes to headlights. Not saying ban lifted vehicles, just you have to come up with a way to relocate the head lights if you do lift.
