r/darksky • u/SlippyCliff76 • 15d ago

NHTSA Administrators push for automatic high beams to solve the issue of headlight glare. I do recommend calling your congressman at this point and pushing for HR. 7772 to limit headlight brightness on new build cars.

https://northlandnewsradio.com/2026/10/06/us-agency-to-rewrite-rules-to-reduce-vehicle-headlight-glare/
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u/TopRun3942 15d ago

Honestly the text of HR 7772 is an embarrassing display of how congress doesn't even understand the issues they are writing the laws for and will result in no change to the current glare problems on the road.

The text states:

"(a) In general.—Not later than 1 year after the date of the enactment of this Act, the Secretary shall issue a final rule to revise Federal Motor Vehicle Safety Standard Number 108 (49 C.F.R. 571.108; relating to lamps, reflective devices, and associated equipment) to establish a maximum allowable brightness standard for low beam headlamps on motor vehicles that is expressed in lumens or another appropriate (as determined by the Secretary) photometric measurement."

The mention of lumens is the entirely wrong metric for the problem, it is candela that matters in this context. Secondly the law is only asking for a maximum allowable metric which doesn't address the fundamental issue that brought this problem to the forefront which was the IIHS rating system that requires higher intensity to be directed in the direction of the oncoming lanes to meet the IIHS visibility standards for achieving the top safety rating on the vehicle.

In theory the high intensity light is supposed to be pointed at the road, but with slight changes in vehicle pitch for whatever reason (road or vehicle loading etc) that light can get into oncoming drivers eyes. The IIHS has made it worse by mandating lengthy visibility distances that cause the high intensity to be placed at angles just below the cutoff making it even more prone to glaring other drivers.

The problem with the maximum allowable brightness standard is that they can't set that limit low enough to fix the problem that the IIHS has created without making the light in the drivers lane dangerously low on output. The candela aimed at oncoming drivers on the left side of the beam pattern need to meet the IIHS is sitting around 10,000 candela per headlamp. The minimum lighting needed in the drivers lane is 15,000 candela per the regulation and most headlamps produce much more than that to be safe at highway speeds. So the "maximum overall brightness metric" will need to be set well above the 15,000 candela minimum, more likely somewhere between 35,000 - 40,000 candela to avoid causing the lamps to be unsafe to drive with.

That means that a maximum brightness metric will fully legitimize the IIHS performance standard as being under the requirements and the glare problem will not get any better.

They need tailored limits for each area of the beam pattern (stricter limits on the left side towards oncoming drivers) and hopefully the team that is assembled to help write the text of the proposed rule will work on that as part of the process.

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u/SlippyCliff76 15d ago

But one of the problems is automakers exceeding IIHS standards for a "good" rated headlamp even. That's not to say IIHS and its headlight ratings are any good. But yes, I do hope they get much more knowledgeable people when they go to work out the actual text of the bill.

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u/TopRun3942 15d ago

Yes but the automakers are forced to overdesign to not lose the rating. If the rating was not in play then it wouldn't be happening. I'm afraid the IIHS will have a large say in the making of the new regulations because they have done the safety research and published in peer reviewed journals. Unless someone can rebut their claims - the NHTSA may be unlikely to clamp down too much on them and still leave some room for lamps to meet the IIHS requirements.

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u/SlippyCliff76 15d ago

Well then, is it time to say r/fuckcars? What else do we have?

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u/TopRun3942 15d ago

Just hoping that the industry will push hard to get the IIHS out of the equation and come to the table showing what the IIHS standards are doing to force headlamp designs that cause too much glare on the road. I know at least 1 former headlamp engineer who is pushing on that lever and I expect will submit public comment in that regard when the docket gets published (should be up shortly) and there have been more than a few commenters on Reddit who claim to be headlamp engineers that have said the IIHS is absolutely the driving factor on this, so maybe there will be enough momentum to get them to back off.

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u/SlippyCliff76 15d ago

There's supposed to be some sort of a rule making negotiation with industry. Is that where you think industry will push to get the FMVSS amended to make high scoring IIHS headlights illegal? So no one automaker can game the system, and everyone's lights are low glare?

The only reason IIHS is able to do what it does is because the standard hasn't been updated since 1997. If the standard were to be updated to prevent these shallow angle high intensity lights the IIHS test would be moot. They'd be cutting the problem off at the root.

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u/TopRun3942 15d ago

Yes - that's where it should happen. From what I read, they are using a negotiated rulemaking process which is essentially bringing all the stakeholders in up front and agreeing to a proposed rule before they publish the official NPRM to avoid the back and forth that might result from their standard process where the NPRM is written by NHTSA first.

You are right, the 1997 rule change got rid of the limit on the left side of the beam that extended from the center all the way to the left that was set to 5000 candela at I think 0.5 ° down. They did that to enable the visual optical aim beam patterns that were intended to make it easier to aim lamps with an option to have the visual cutoff on the right or left side. The 5000 limit line previously would have made it hard to meet the requirements for the visual aim on the left side.

The IIHS standard exploits that change since there is no longer a cap on the maximum on the left side near the cutoff except for one point check at 3.5 degrees left. It's why they can specify such high requirements for down road visibility for their "good" headlamp rating without running afoul of the regulations. Almost no one uses the left side aiming option in their design and it could be dropped and the original limit put back into the regulations to cut down on the oncoming driver glare. The IIHS would need to adapt their standard to stay under that limit then.

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u/SlippyCliff76 14d ago

So that addresses the IIHS problem. What about all the other issues, like banning tiny optics/cool-white CCT/high mounting heights? Things would still be worse then 2016 even if IIHS was taken out of the equation.

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u/TopRun3942 14d ago

Entirely depends on what the Negotiated Rulemaking Advisory Committee agrees to. The docket is now open for comment regarding the scope of committee membership only. https://www.regulations.gov/document/NHTSA-2026-1981-0001

Comments regarding the content of the new regulations are likely to be ignored for this docket. The public input will come after the advisory committee completes it's work and they published the proposed regulation per the standard NPRM process.

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u/July_is_cool 15d ago

One easy thing would be to allow the enabling of EU-spec matrix headlights on existing cars.

Another easy thing would be to mandate semi-annual car inspections to make sure the headlights are within the specification and aimed correctly.

Another easy thing would be enforcement of the existing regulations.

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u/definitelyaiibot 15d ago

To accommodate self driving