Q: You’ve written about the brightness of aftermarket headlights, but there’s a more common problem: the brightness of many factory-installed LED headlights on late-model cars. The glare from the modern headlights of oncoming cars can blind other drivers. Have regulators failed to consider the safety hazards created by the new headlights?
Let’s start with this: headlights are a compromise in an already compromised situation. Driving at night is dangerous. The vehicle occupant fatality rate at nighttime is three times higher than the daytime rate. We can’t blame that all on the darkness; speeding, impairment, and unbuckled occupant rates also increase at night. But a reduced ability to see does compromise our driving ability.
Until the robots take over driving, we’ll need headlights to see where we’re going. That’s the next compromise. Our headlights should be bright enough to illuminate the road but not so bright that they blind oncoming drivers.
We’ll address the first half of the compromise first. Low beam halogen reflector headlights (the kind that are less likely to cause glare) provide enough light to see a non-reflective object (like a pedestrian) at 300 feet. That works out to a top speed of 39 mph before we’re overdriving our headlights. Unless we’re willing to have nighttime speed limits of 35 mph, that’s not enough light to drive safely. New LED headlights push that out to 450 feet, and 52 mph. That still falls short of the kind of illumination we actually need for nighttime driving on many highways. To quote one report, “Headlights found in U.S. vehicles fall short on safety.”
Should we go even brighter? It’d be good for the driver, but what about everyone else? We’re complaining more about glare as LED headlights become more common. Are our complaints merited? The two-part answer is for sure, and almost not at all. Headlight researchers divide glare into two categories – discomfort and disability. Disability glare results in a measurable reduction in driver ability. Discomfort glare is unpleasant but doesn’t appreciably increase driving risk. Modern headlights have increased discomfort glare, but crash data show that there hasn’t been an increase in glare-related crashes. Meanwhile, these brighter headlights reduce nighttime single-vehicle crashes by about 20 percent.
When we do the math, it seems like those of us who don’t like the glare might have to put up with it. If you don’t like that answer, you’re not alone. There’s a petition with over 80,000 signatures at the time of writing demanding that we ban blinding headlights.
This is somewhat an American problem. Adaptive Driving Beam (ADB) headlights, which adjust to keep light out of oncoming drivers’ eyes while still illuminating the road, have been available on European cars for 20 years now. With ADB you can have both brighter headlights and reduced glare. It wasn’t until 2022 that the US updated the rules about vehicle lighting to allow them here.
So we should see this technology showing up on all our cars now too, right? Probably not. If regulators had crafted regulations consistent with the globally accepted standards for ADB headlights, it would have been immediate. Some imported vehicles already have ADB technology built in, but they’re not allowed to turn it on. Instead, the US made their own rules, which means systems will need to be engineered specifically for the US market and will likely take years. (With one exception – Rivian has ADB headlights on their electric SUV. The new rule and the development of their vehicle coincided, so they designed it that way from the start.) And the rest of us; for now we’re living with an unsatisfactory compromise.
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