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Why Are Trucks Flashing Their Lights at Me?

Why Are Trucks Flashing Their Lights at Me?

If you’ve been driving down a highway and noticed a truck flashing its lights, it’s likely not by accident. Headlights can serve a larger purpose than just improving a driver’s visibility. So why do semi-truck drivers flash their lights? Let’s see!

What’s the Official Meaning of Flashing Your Headlights While Driving?

There is no official meaning of flashing headlights, but taken in the context you may be able to figure out what they are trying to convey. If you get flashed from oncoming traffic and you realize you forgot your brights on, it’s pretty easy to figure out what they were saying.

Non-truck drivers typically flash their headlights to warn against speed traps. They’re trying to be helpful by alerting other drivers that law enforcement is sitting nearby watching traffic. The flashing lights warn drivers to slow down or adjust their driving to avoid getting a ticket.

However there are many other reasons trucks flash their lights, so let’s take a look at a few of them.

Is It Illegal to Flash Your High Beams at Someone?

You may think you’re doing other drivers a favor by flashing your high beams at them, but you could be breaking the law. For example, Michigan laws prohibit drivers from using high-beam lights within 500 feet of an oncoming vehicle.

If law enforcement catches you, you can even receive a citation. You’ll be breaking the law if you’re trying to warn of a speed trap or remind the other driver to use their low-beam lights.

Traffic laws vary by state, and you’ll want to check the specific rules of the road for where you live or are driving. They’re likely to change as soon as you cross the state line. If you live in an area that borders a state or states, you’ll want to be familiar with the laws unique to each state.

Pro Tip: You likely know truckers must drive at slower speeds, but Do RVs Need to Obey Truck Speed Limits? Find out!

Truck driving while flashing lights at other drivers at night
There are many reasons why truck drivers may flash their lights at you while you’re driving.

Why Do Semi-Truck Drivers Flash Their Lights?

Semi-truck drivers often use their truck’s headlights and the various lights on their trailers to communicate with other semi-truck drivers and passenger vehicles. If you notice a semi-truck or other vehicle flashing its lights at you, they’re likely trying to tell you something. Let’s look at a handful of things they could be trying to communicate.

Speed Traps

Law enforcement helps keep the general public safe by using radar detectors to monitor the speeds of vehicles on the road. Drivers often refer to these as “speed traps.” They’re relatively common on interstates or other highways with a reputation for drivers being in a hurry. A vehicle may notice the speed trap when driving through an area, and the driver will flash their lights to warn oncoming vehicles.

The legalities of warning drivers about speed traps will vary by state. Speed traps are effective ways for law enforcement to stop law-breaking drivers and enforce laws.

It’s not uncommon for law enforcement to arrest a driver or passenger for a much more serious crime than speeding. They’ll sometimes catch hard criminals with warrants or with illegal substances. So while we understand wanting to be nice and warn other drivers, you’re not always doing your local community any favors.

Objects in Road

Another common reason trucks flash their lights is to warn of objects in the road ahead. This could be an accident or object in the road ahead. It could be a blown tire, animal, or a piece of furniture from a loaded-down moving truck.

A driver may be trying to warn you of a potential hazard that could cause a serious issue for you and others on the road. Reducing your speed or your awareness could help you avoid an accident.

Truck driver flashing lights on highway
If you’re wondering why semi-truck drivers flash their lights at you, it can definitely be circumstantial based on your or their driving.

Safe to Merge

Semi-trucks can be 70 feet long, making it very difficult to judge distances in front and behind them. A truck driver may flash their lights to indicate that it’s safe to merge, especially if the passing vehicle is holding up faster-moving traffic behind them.

If truck drivers notice that a driver wants to merge into the lane, a quick flash of their lights will help give the other driver the confidence to know that it’s safe. Instead of flashing their high-beam lights, they’ll typically turn their headlights on and off quickly unless it’s daytime when they sometimes use their high beams.

While they mainly use this for communication between trucks if you have your blinker on before merging they may signal you as well. This is common for anyone with a trailer.

Saying Thanks

Truck drivers will often use their trailer lights to show appreciation or thank other drivers. There are various reasons a truck driver may want to say thanks. But that’s typically because you made some adjustments to accommodate them.

Whether you reduce your speed to allow them to change lanes or give them space to make a traffic maneuver, they may be trying to show gratitude.

Truck drivers have very challenging and stressful jobs, and not all drivers show them as much consideration. They likely are trying to show their appreciation so that you’ll continue to be aware of semi-truck drivers and defeat the stereotype that truckers are rude or dangerous drivers.

You Made a Mistake

While flashing lights for some trucks might be a way to show thanks, others may use them to say something you don’t want to hear. By flashing their lights at you, they may be trying to communicate some four-letter words that aren’t necessarily family-friendly.

This would likely be because you were driving poorly or dangerously. Truck drivers often have a short fuse for unsafe drivers as they cause accidents and cause travel delays.

If you’re wondering why do semi-truck drivers flash their lights at you sometimes, if you change lanes without a signal, don’t give the proper distance between you and other vehicles, or drive erratically, they’re likely not trying to thank you. They’re also probably not waving a finger at you to tell you that you’re the #1 driver on the road.

Truck driver smiling at camera
Flashing lights can be a positive or negative signal based off of your driving.

Is It Safe to Flash Your Headlights at Other Vehicles?

Flashing your headlights can be very dangerous for you and other drivers on the road. By flashing your lights at an oncoming vehicle, it could momentarily obstruct their vision. The last thing you want is a vehicle that weighs thousands of pounds to be coming at you under the direction of a driver who can’t see. Flashing your high beams during the day likely won’t blind them, but it can cause major visibility issues at night.

Flashing your high beams at a vehicle in front of you is less dangerous but can be a distraction. The driver may momentarily look in the rearview mirror and take their eyes off the road. Depending on the road or the weather conditions, it could increase the risk of an accident. However small the increase may be, the last thing you want to do is cause a dangerous situation for a fellow driver.

Most semi-trucks and buses have additional headlight flashing buttons and capabilities that cars do not. Many times they can flash just the trailer lights, marker lights, or even dim the headlights to flash them instead of using brights. They have these features because they use light flashing much more than cars.

Aerial image of truck driving on road at sunset
You can also flash your lights at truckers to communicate with them.

How to Flash Your Lights to Help Truckers

Before flashing your lights at truckers, you want to know how to do it correctly. During the daytime, flashing your high beams likely won’t cause any issues. If you’re driving a smaller vehicle, your high beams may not reach high up enough to cause any visibility issues for a bigger truck at night. However, there is a correct way to flash your lights to help truckers.

During the daylight, turn your headlights on and off a few times. This will be enough for them to see and respond appropriately. However, we don’t advise turning your headlights on and off when you need them for visibility. A quick flick of your high beams will do the trick in these instances. The trucker will likely see the light change in their mirrors and respond. As we mentioned earlier, they may even flash their trailer lights back at you to say thanks.

Pro Tip: Ever find yourself wondering What Is a Runaway Truck Ramp? We uncovered how to and who can use them.

Trucking Tip of the Week 11: Flashing Your Lights

Know What Those Flashing Lights Are Trying to Tell You

Now you can drive confidently, knowing what those flashing lights for trucks are trying to tell you. There’s a good chance that truckers are trying to help you or to keep you safe while driving by using their lights. If you’re one of those bad drivers on the road putting others in danger by driving recklessly, take the flashing lights as a reminder that you need to adjust your driving habits.

Have you every noticed a truck driver flashing their lights at you? Tell us about your experience in the comments!

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About Mortons on the Move

Tom & Caitlin Morton of Mortons on the Move gave up the stationary life for one where they are constantly on the move. They are full-time travelers, television hosts, and digital media producers.
They left their jobs, sold their house and possessions, and hit the road in September 2015 in their full-time “home on wheels”. Since then they have traveled the US, Canada, and even internationally by RV.
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