Why Do Truck Drivers Flash Their Lights at Oncoming Traffic?

The behavior of truck drivers can sometimes be perplexing for noncommercial (i.e. commuting) drivers, who are often curious about why the massive vehicles they're sharing the road with have spikes on their wheels or stuffed animals strapped to their grilles.

Another puzzler: Why do truck drivers flash their lights at oncoming traffic?

Consider it a method of communication, writes Broken Secrets. When truckers flash their headlights or hazard lights, they’re doing it as a courtesy to let you know that there might be a situation ahead that’s going to require your attention. That can mean anything from congested traffic due to an accident or a police presence to hazardous road conditions or a traffic jam.

You might get a quick burst of flashing lights even if you’re following a truck in the same lane. That’s because truck drivers are seated higher than noncommercial drivers and have a better line of sight. Truckers also get information from radio communications with other truck drivers. The lights may be an attempt to give you a heads-up. If you see them, it’s a good idea to slow down and be alert for changing road conditions.

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Other vehicles can communicate with truck drivers. If a truck is looking to merge into your lane, you can flash your headlights to signal they have sufficient clearance to do so. The driver might then flash their lights to acknowledge the signal. Truckers may also let other drivers in front of them looking to merge know they have the space by flashing. (While some trucks have blind spot monitoring similar to newer vehicles, not all do, and many truckers still rely on their mirrors.)

Occasionally, there will be a dust-up in relation to communicating via headlights. Police in Missouri once ticketed a man who flashed his lights at drivers in attempt to warn them of police radar. A U.S. District judge shot the ticket down in 2014. Others have cautioned about trying to use headlights for reasons other than obstacles or merging, as signals can vary by region.

Since most drivers don’t have CB radios, truckers use headlights to “talk” to others on the road. Considering their experience and scope of information about what lies ahead, it’s always wise to listen. And if you're looking for useful gifts for truck drivers, take a look at our gift guide.

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A version of this article was originally published in 2022 and has been updated.