IIHS Research Debunks Common Belief: Brighter Headlights Not Causing More Crashes, Glare is a Minor Factor
New research from the Insurance Institute for Highway Safety (IIHS) suggests that the widely perceived issue of blinding headlight glare from modern LED lights is not a significant factor in nighttime crashes. According to their study across 11 U.S. states between 2015 and 2023, headlight glare was cited in only one to two out of every thousand nighttime crashes, a percentage that has remained stable despite increased headlight power. While acknowledging glare can be uncomfortable, IIHS President David Harkey emphasizes that “insufficient visibility” contributes to far more crashes. The study found glare-related crashes most often involve older drivers, wet conditions, older cars, and local, undivided roads. The IIHS is urging automakers to adopt advanced technologies like adaptive driving beam headlights and lane departure systems to further enhance nighttime safety.
Headlight Glare: Perception vs. Reality
While many drivers complain about intense glare from modern headlights, IIHS research provides a different perspective.
- Common Complaint: With the advent of advanced LED headlights, “glare has become a much more prominent complaint among drivers who feel ‘blinded’ by oncoming cars.”
- IIHS Findings: A new report from the IIHS suggests that glare “isn’t as much of a problem as everyday drivers think.”
- Minor Crash Factor: Headlight glare was implicated in only a “tiny fraction of nighttime crashes,” cited as a factor in just one or two out of every thousand nighttime crashes across 11 U.S. states between 2015 and 2023.
- Stable Percentage: This percentage has remained “virtually unchanged over the past decade,” even as headlight power and visibility-improving light output increased.
- Visibility More Critical: IIHS President David Harkey states, “Although it can certainly be uncomfortable, headlight glare contributes to far fewer crashes than insufficient visibility.”
Characteristics of Glare-Related Crashes
The study identified specific patterns associated with crashes where glare was a contributing factor.
- Low Frequency: Fewer than 150,000 of about 24 million total crashes had glare coded as a contributing factor, with a much smaller fraction occurring at night.
- Specific Conditions: Glare-related crashes tended to be:
- Single-vehicle incidents.
- More frequent in rainy or wet road conditions.
- Happening on local, undivided, two-lane roads with low speed limits.
- Driver Demographics: Drivers in these crashes tended to be older (especially over 70) and were more likely to be driving older cars.
- Improvement in New Cars: IIHS found that the glare rate was highest in 2015 and lowest in 2020, suggesting that glare emitted by new car headlights has decreased over the years (from 21% of 2017 models producing “excessive” glare to 3% of 2025 models).
Recommendations for Enhanced Nighttime Safety
The IIHS advocates for advanced technologies to further reduce crash incidents.
- Lane Departure Warning/Prevention: Can “cut the already small number of glare-related crashes by more than half.”
- High-Beam Assist: Automatically switches between high and low beams when detecting oncoming vehicles.
- Adaptive Driving Beam (ADB) Headlights: A feature common in European luxury cars, approved by NHTSA only in 2022.
- U.S. Lagging: The U.S. is “relatively behind other regions” (Canada allowed ADB since 2018).
- Rivian Adoption: Rivian is one of the only U.S. manufacturers to feature working ADB headlights, enabling them via a software update in August 2024 for 2025 Gen 2 models.
- Future Hope: IIHS hopes this technology will “trickle down into more consumer brands.”
Final Thoughts
The IIHS’s latest research offers a surprising but data-backed conclusion: the perceived increase in headlight glare is not translating into a rise in crashes. While the discomfort of bright oncoming lights is undeniable, the actual safety risk is minimal compared to other factors. This study reinforces the importance of improving overall visibility at night, a goal that modern LED technology has largely achieved. The IIHS’s recommendations for widespread adoption of adaptive headlights and lane departure systems point towards a future where technology can further mitigate the challenges of nighttime driving, making roads safer for everyone, especially older drivers and those in adverse conditions.
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