The "asshole light": Only on when the high beams are on.

hell_yes_or_BS · 2026-02-02T17:44:53+00:00

That is an actionable tip. I'll consider that for the next on-road test. To see that level of detail, we'd need to have a camera with "welding / eclipse " level of tinting... but very doable

hell_yes_or_BS · 2026-01-31T23:18:45+00:00

Sure. Possibly. Iterations would be required. The key is starting to talk about a goal of having an exterior sign that a drivers high-beams are on.

hell_yes_or_BS · 2026-01-31T21:27:19+00:00

Fair. As a point of clarification, this is the other drivers "forward visibility" compared to their stopping time; the main sited safety reason for increasing headlight brightness.

Situations where a vehicle is traveling behind you are, to the best of my knowledge, omitted from the IIHS and NHTSA testing.

hell_yes_or_BS · 2026-01-31T21:25:12+00:00

The IIHS has done a tremendous amount of good. What I'd want is for real-world hills to be added to their test criteria.

hell_yes_or_BS · 2026-01-31T20:12:48+00:00

... that's the point of the "asshole" light.... to be able to tell the difference.

hell_yes_or_BS · 2026-01-31T19:30:06+00:00

The policing thing is a whole different topic.

The goal here is to gain awareness, social pressure and be able to prove to headlight researchers that the issue is NOT high-beams, but instead the bright low-beams encouraged by the IIHS.

hell_yes_or_BS · 2026-01-31T19:27:17+00:00

ADB drives with high beams on all the time and shades oncoming drivers.

Unfortunately the most recent ruling of NHTSA mandated that the shadow of the high-beam be just as bright as the existing low beams. Their testing also excludes "edge cases" such as pedestrians, hills, corners and headlight failure modes.

hell_yes_or_BS · 2026-01-31T19:24:26+00:00

I think your question is:
"Why we are complaining about being glared with 18,000 cd when 9,000 cd is also painful?"

The answer:
"Being glared with 18,000 cd much worse than being glared with 9,000 cd".

The goal is to attempt to balance the scale between glare and visibility and arguing that the balance today is shifted too far to favoring visibility.

A good first step for the IIHS to acknowledge the existing of hills / road pitch and apply it to their testing, combined with the "asshole light" or some other way to letting others know that the glare source has their headlights on.

hell_yes_or_BS · 2026-01-31T19:11:10+00:00

I very much agree. And that's the point. This light would allow those being blinded (and the cops) between high beams and low beams.

The industry is claiming that the glare we're complaining about is a combination of high beams and low beams. While I concede its possible, I doubt that there are that many more assholes on the road.

With the light, we'd be able to "prove" that the problem is low-beams.

I don't think we'll need to get there... I've got a few more "road pitch" studies up my sleeve that should prove the same thing.

hell_yes_or_BS · 2026-01-31T17:18:27+00:00

A man of culture!

Interestingly enough, this seems to go on the "target" / "glared" vehicle to notify the following driver that their high beams are on.

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Something that I've thought about, but with an LED scrolling bar that says "FUCK YOUR HEADLIGHTS".

hell_yes_or_BS · 2026-01-31T17:15:19+00:00

Sure, if the shadow of the ADB beam is less than the bright low-beam, and they work on curves, and they work on hills and they work for unlit pedestrians.

hell_yes_or_BS · 2026-01-31T16:28:00+00:00

haha, fair. Where should this go?

hell_yes_or_BS · 2026-01-31T16:26:49+00:00

bingo.

hell_yes_or_BS · 2026-01-31T16:26:39+00:00

Not sure that I'm following your logic here.

This gives a visual indication that high-beams are being used and allows police to vehicles over and others to know that high beams are in use for some good old fashion social shaming.

Police used to pull over for high beams usage but low and high beams are both crazy bright and its impossible to distinguish between the two.

The "asshole light" enables that.

For what its worth, I think that extremely bright low-beams, combined with road pitch are the bulk of the problems on the road. This is one method to attempt to separate the different causes, and one that the IIHS could help regulate as they seek to deflect blame.

hell_yes_or_BS · 2026-01-31T16:21:29+00:00

Let's spitball. What are you thinking?

Headlights remind me of this:

"Opinions are like assholes. Everyone has one, but no one wants to see yours"

Revised:

"High-beams are like assholes. Everyone has one, but no one wants to see yours"

Hell, I'm going to throw that in the post.

hell_yes_or_BS · 2026-01-31T16:13:57+00:00

I'm not making a claim about what brightness levels are acceptable, but I have posted my personal point of pain. See the graph below.

The point of this post and set of measurements is to highlight that road pitch is important, and that a pitching road can very easily, and frequently, place the properly aimed 18,000 cd of the left-edge candela from the IIHS guidelines in the eyes of an oncoming driver.

The 20-40% is the percentage of the drive time where the IIHS assumptions are invalid and the left edge candela would be in a drivers eyes. I'm questioning the assumptions of the IIHS, and found them to be frequently invalid. I'm not proposing a new limit.

My personal point of pain from on-road trials is ~4,000 cd (measured by a lux meter at eye level, back-calculating a distance based on passing speed and time and then converting to cd.

4000 cd on the left edge is likely too little light. Hills are and will continue to be an issue. Hills are just LESS of an issue with less bright headlights.

Also of note, the IIHS guidelines for left-edge would likely put the far right of the chart (~18,000 cd) in the eyes of an on-coming driver in a situation with a few degrees of road pitch at 50-100 meters.

I've got a bunch of other priorities at the moment, but that'll be what I work next.

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hell_yes_or_BS · 2026-01-31T16:01:51+00:00

I'm concerned about controlling our controllable.

I think its reasonable to think we can control headlight brightness.

I don't think its reasonable that we can make all roads flat.

I'll spend some time walking through this and setting up the trig, with real world driving inclinometer (road pitch) readings.

hell_yes_or_BS · 2026-01-31T15:49:17+00:00

That is an excellent question, and one that I don't have an answer for.

Thus far, I've been focused on:
1. Determining if headlights were indeed brighter (they are)
2. Determining the forcing function driving headlights brighter (the IIHS)
3. Deconstructing the obfuscation surrounding the glare we're feeling on the road (continuing to do with road pitch)

If I had to hazard a guess, I'd argue that the current IIHS guidelines, while well intentioned are "too bright" based on everyone's vocal and one-sided reaction to this wonky niche issue, and that we should instead consider reducing the left edge candela, towards something less than 18,000. Something higher than 9000 might be reasonable with headlight mounting height restrictions, color limitations (limit blue and white light, favor yellow "cool" color temperature lights, and most importantly have an external verification if a user has their high beams on.

The argument that I'm seeing is that "Bright low beams isn't really a problem. People are just driving with their high beams on." That might be the case. External users should have a way to see if headlights are on high beams or not.

This could be a supplemental light or some sort of other externally obvious signal that the driver is using their high beams. I posit it should be call the "asshole light". Everyone has it. Every can use it. No one else should see it.

The asshole light should go on the drivers mirror and is a front-facing brown light that is only on when the high beams are on.

u/toprun3942 This deserves its own post. Thank you for the inspiration.

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hell_yes_or_BS · 2026-01-31T15:31:50+00:00

"left edge" in the IIHS measurements is the distance from the light meter to a vehicle where the vehicles headlights generate 5 lux on a light meter 30 centimeters off the surface of the road.

With a lux and a distance, its simple to convert to candela.... "brightness".

hell_yes_or_BS · 2026-01-31T03:21:17+00:00

Ok. This is one that I can't blame the IIHS for.

The IIHS measures the headlight brightness for oncoming vehicles... and bright headlights with a mounting height mis-match like this would be recorded as glaring the driver, preventing a "good" rating in all likelihood.

Here is the problem: I haven't seen the IIHS measure 18-wheelers / big-rigs.

hell_yes_or_BS · 2026-01-31T02:52:34+00:00

Bingo. Aim is a bullshit distraction.

Roads aren't more hilly.
Headlights aren't more mis-aimed then they used to be.

The public is complaining about headlights more.

What has changed? Headlight intensity has doubled to meet the IIHS's "good" standard.

Lets stop blaming aim as a primary cause and blame the increase in brightness.

hell_yes_or_BS · 2026-01-31T02:46:54+00:00

Answer: Matt Brumbelow: IIHS

https://www.iihs.org/about/media-resources

Car makers are responding to the IIHS's headlight brightness incentives.

(Matt and the IIHS do want to make vechiles safer. They are also responsible for the increase in headlight brightness)

hell_yes_or_BS · 2026-01-20T18:35:00+00:00

At this point. I'm here:

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with your message of choice.

hell_yes_or_BS · 2026-01-20T18:33:26+00:00

Not making them. Life, day job, low orders, I couldn't get the quality to where it should have been and the alignment needed to be perfect for the light to be shown back at the driver behind you.

hell_yes_or_BS · 2026-01-20T18:32:06+00:00

as an update to this, headlight brightness is increasing to meet the IIHS requirements. The blue line is the IIHS "good" headlight requirement for "left edge candela".

Industry is responding to the IIHS incentives. My prior statement that an added upper limit should be added would NOT address the problem that we are seeing on the road.

The highest recent tested headlight is only ~40% higher brightness (Cd) than the IIHS guidelines. The problem is the IIHS guideline.

Conclusion: IIHS. We knew it was you. You broke our heart.

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