Avoiding High-Beam Blindness

Q: What are the rules and regulations about headlights? It seems like the low-beam headlights on some new vehicles are as bright as an older car’s high-beams. What about the height of headlights on big trucks and SUVs? What’s the best way to handle an oncoming driver that appears to have their high-beams on? Can I flash my high-beams at them?

A: Lots of people get annoyed over how drivers use (or misuse) headlights, and with good reason. I can’t think of any other driving behaviors have the potential to temporarily blind another motorist. Okay, maybe “blind” is hyperbole, but anyone who drives at night knows the experience of encountering an oncoming driver who fails to dim their high-beams, and how much that impacts vision.

The questions begin by asking about the rules, and that’s a good place to start as it will set the groundwork for the remaining questions. Drivers are required to use headlights from a half hour after sunset until a half hour before sunrise and whenever lighting or weather conditions cause low visibility. Many drivers have gotten in the habit of always turning their headlights on to increase visibility, and many new cars are equipped with daytime running lamps (DRL). This feature automatically turns on the headlights when the car is running. Just be aware if you have a DRL-equipped car: It doesn’t automatically turn on your tail lights. Turn on your headlights manually (even though the car already turned them on for you) to illuminate your tail lights. Otherwise, at night you’ll be nearly invisible from behind. If you see a car at night with headlights on but no tail lights, it’s probably equipped with DRL.

The brightness of a vehicle’s headlights is limited by the Federal Motor Vehicle Safety Standard (FMVSS). Any new car is required to meet this standard, so these new headlights are not technically “too bright.” However, new cars with LED or HID lights tend to have a bluish tint, while older headlights have a yellowish tint. Our pupils don’t respond as quickly to bluish light, causing our eyes perceive more glare from lights on the blue end of the spectrum. This glare is what makes us think the lights are brighter. Once we get onto the topic of vehicles with after-market lighting systems, disregard everything I’ve just said about FMVSS limits. Many aftermarket LED and HID lights are labeled for off-road use only and don’t comply with FMVSS. That doesn’t seem to stop some drivers from installing them in their vehicles.

Car headlights are limited to a height between 24 inches and 54 inches from the ground to the center of the light. There are a few jacked up trucks and SUV owners that violate this law, but often the problem isn’t that the headlight is higher than 54 inches, but that the headlight is improperly adjusted. The law requires that headlights are properly adjusted.

Drivers are required to dim their headlights when approaching an oncoming vehicle within 500 feet or when approaching the rear of a vehicle within 300 feet.

That covers the law, but what do you do when you encounter another driver who disregards or is oblivious to the law?

It’s common to see drivers quickly flash their high-beams at an oncoming car, but is it legal? Since the law requires that drivers dim their headlights within 500 feet of an oncoming car, a strict interpretation of the law would indicate that flashing your high-beams is only legal when you’re more than 500 feet away from the approaching car. Here’s the catch: since they’re more than 500 feet away, they are using their high-beams legally, so you have no reason to flash your high-beams at them until it’s illegal to do so.

Based on past experiences, I tend to believe that it’s a wasted effort trying to train other drivers from inside my vehicle. Instead, I try to avoid looking at their headlights. I know, it sounds obvious, but for some reason it’s hard to do. It requires striking a balance between looking away from the car and keeping it in your peripheral vision. Many traffic safety professionals recommend looking toward the right edge of your lane. I’d just add that you don’t want to look so far right as to lose any perception of the oncoming car. Bright headlights or not, I always want to know that an approaching vehicle is fully in its lane.


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