If you've driven at night in recent years, you'll know how big of a problem blinding oncoming headlights have become. The increasing popularity of LED headlights as replacements to traditional halogens certainly contributes to the issue, but through my own experience and research I believe there's an aspect of LEDs that is especially dangerous: their incompatibility with many of the daytime running lights systems found on modern cars.

I recently bought a 2011 Subaru Outback, and when the halogen high beam bulbs burnt out, I decided to replace them with a set of LEDs, as I'd been seeing on other cars on the road. What I didn't realize is that my car, like many other models, uses the high beams at reduced power as daytime running lights. LEDs do not become dimmer at reduced power, they stay at full brightness, in effect causing the high beams to activate instead of the daytime running lights. This can already blind oncoming drivers during the day, but if these lights are accidentally left on at night, it could completely obscure other drivers' vision. At speed, this can have deadly consequences.

Take this hypothetical: A driver starts their trip at dusk with their nighttime lights deactivated. As it gets darker, they are still able to see fine because their daytime running lights are too bright, meaning nothing prompts them to activate their nighttime lights. Because their DRLs share a bulb with the high beam, that bright light is angled upwards and outwards, and oncoming traffic is blinded from the road in front of them.

This problem with daytime running lights is not the only cause of blindness to oncoming traffic, but it's a contributor that is not as well known, and along with other causes is not addressed by existing regulations. Left unchecked, LED headlights will continue to gain popularity and continue to blind PA's nine-million drivers

Current PennDOT Vehicle Equipment and Inspection Regulations don't contain any requirements, or even a definition, for daytime running lights. During state-mandated annual inspections, mechanics already check various specs of the vehicle's external lights. Adding maximum brightness levels for DRL systems to state inspections is an easy step towards safer night driving conditions in Pennsylvania.

If you feel strongly enough, you can write a letter to Governor Shapiro; I've already sent one myself.