Blinded by the Light: the Problem with LED Headlights
Having a good set of (working) headlights is a crucial feature of any motor vehicle, assuming you want to be able to see the road ahead of you when there’s a lack of sunshine. Headlights are also essential to be noticed by other cars and traffic participants, but if installed improperly they can end up blinding an opposing driver with potentially fatal results. This is a major worry with LED lamps that are increasingly being installed in cars, often replacing the old-style halogen bulbs that have a very different color spectrum and beam patterns, to the dismay of fellow road participants.
This headlight glare can also be simulated in driving simulators, as in a 2019 article by [B.C. Haycock] et al. where the effect is of course diminished because displays can only get so bright. Of note is that it’s not just LED lights themselves, but also taller vehicles and misaligned headlights, all of which makes it important that the angle of your car’s headlights is proper. You want to see the road in front of you, after all, not illuminate every house in the nearest settlement two klicks away.
Compounding the problem is that the shorter wavelength, blue-ish light of LED headlights is more energetic than the more reddish, longer wavelength of halogens and are generally perceived as more intense by our eyes. Ultimately the solution appears to be adaptive driving beam headlights (ADB), a technology that constantly adjusts the headlights to the circumstances. ADB has been common in e.g. Europe already for the past 15 years, and is allowed in Canada since 2018 and in the US since 2022 after a rule change by the NHTSA.
With plenty of improper headlights on vehicles in North America still, it’s best to practice defensive driving, with a brighter dashboard illumination, anti-glare coatings and safety squinting when a miniature solar system passes by during an night-time drive.