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Why Do Semi Trucks Use Hazard Lights? (12 Facts For Newbies)

Semi trucks may seem like vehicles that are completely out of this world.

However, many of their concepts are similar to those of standard road cars.

Semi trucks use hazard lights, just like other cars. However, have you ever wondered if they are the same and if they are used in the same way?

Read on to find out more…

Here’s a summary of why Semi Trucks Use Hazard Lights:

Semi trucks use the same amber hazard lights that all other cars do. Semi trucks use their hazard lights for different reasons, from communication to warning other motorists of potential dangers ahead. However, driving with hazard lights on is illegal in some states.

What Hazard Lights do Semi Trucks Have?

Semi trucks use standard amber hazard lights similar to the ones found on cars and SUVs. They work in the exact same way too.

This is because semi trucks need to abide by the same rules as other vehicles on the road. Using the same hazard lights keeps everything consistent with other vehicles.

What’s the Difference between Hazard Lights and 4-Way Flashers?

Hazard lights and 4-way flashers are the same thing. There are different names for the hazard lights found on vehicles.

Another name for them is emergency lights. These are the indicators or turn signals on each corner of the vehicle.

When the hazard lights are active, each of the four lights will flash at the same time to warn other drivers of potential dangers ahead on the road.

What is the Function of Hazard Lights in a Semi Truck?

Hazard lights have the same purpose on semi trucks as they do on other vehicles. Their main purpose is to warn other road users.

They can be used to warn other road users of something that is happening on the road ahead, or even if the vehicle is broken down on the side of the road.

Why do Semi Trucks Drive with their Hazards On?

Sometimes semi trucks will drive with their hazard lights on. This is usually for good reason. Semi truck drivers are experienced, and they will always have their hazard lights on for a reason.

The first reason is that there might be a danger ahead on the road. This could be anything from a car accident to animals crossing the road.

Semi trucks may also turn their hazard lights on when the traffic begins to back up ahead of them. Semi trucks take a long distance to bring to a stop.

Drivers will turn their hazard lights on to let you know that they are slowing down and you should do the same to prevent having to jump on the brakes unexpectedly.

Semi trucks are also extremely heavy vehicles. This means they could be very slow-moving when going uphill. Semi truck drivers may use their hazard lights when going uphill to show that their truck is moving slowly.

Semi truck drivers may also drive with their hazard lights on when they are hauling a heavyweight and are driving slowly in general. This is to show other road users that the vehicle is moving much slower than the speed limit.

When the weather conditions are poor, semi truck drivers will also use their hazard lights. This will make it easier for other drivers to see their vehicle on the road.

Should a Semi Truck Have its Hazards on when Stopped or Parked?

Semi trucks will often use their hazards when they are stopped. This is most often when they are on the side of the road and they may be obstructing it.

When a semi truck has broken down, it needs to indicate that it has stopped on the side of the road. This is done by using the hazard lights.

Semi trucks can also sometimes obstruct a section of the road or a lane. The hazard lights will help to signal this to other road users and notify them that the truck will not be moving.

Do Semi Truck Drivers use Hazard Lights to Communicate?

Semi truck drivers will often make use of their hazard lights to communicate with other drivers on the road.

In the majority of cases, using the hazard lights will indicate danger. The danger can be caused by several factors.

The first is that the vehicle is moving slowly or stopping entirely. With such a large vehicle, it can be difficult for other motorists to judge the speed at which a semi truck is traveling.

Oftentimes when the semi truck is hauling heavy cargo or is going uphill, it will be traveling slower than the speed limit. The hazard lights will warn other drivers that the semi truck is traveling slowly.

Semi truck drivers have a much higher seating position than any other car on the road. This allows them to see much further up the road.

Their increased visibility allows them to see dangers ahead on the road much earlier than other cars. Semi trucks will use their hazard lights to indicate that there is a danger ahead and that you should slow down.

Why do Semi Trucks Flash Hazards?

Before radios and easy forms of communication, semi truck drivers developed their own form of sign language. This is still somewhat used to this day.

Flashing the hazards once or twice is a form of this sign language that was developed some time ago. In the majority of cases, it means “thank you”.

You may see semi truck drivers using their hazard lights to say “thank you” if you allow them to merge into the lane in front of you for example.

How Fast can a Semi Truck go with Hazard Lights On?

Hazard lights do not affect the speed of a semi truck. Technically, a semi truck can go at any speed and still use its hazard lights.

However, in some cases, semi truck drivers could get into trouble for using their hazard lights on without good reason.

The speed of a semi truck is affected by the weight of the cargo it is hauling. The heavier the trailer, the slower the truck will go.

Trucks will also go slower when they need to go uphill or stick to a certain speed limit.

Should you put your Hazards On in the Rain?

It is not always necessary to use hazard lights when it is raining. However, in cases where the weather conditions are severe, hazard lights may be necessary.

When there is heavy rain, fog, or extremely poor visibility, it’s a good idea to make use of the hazard lights on a semi truck.

During poor visibility situations, you will most likely be driving slower than usual. Due to the lack of visibility, you will need to make it easier for other motorists to spot your semi truck.

Using the hazard lights on your semi truck is the easiest way to do so. The amber color stands out and will help others to quickly spot your vehicle on the road.

What States is it Illegal to Drive with Hazard Lights On?

In some states, it is illegal to use your hazard lights while driving. The law states that hazard lights should only be used when your vehicle is stationary.

This is to warn other motorists that your vehicle is temporarily obstructing the road.

The law continues by stating that hazard lights cannot be used while driving as an excuse for dangerous or illegal driving or parking.

The following states do not allow you to drive with your hazard lights on (exception):

  • Alaska
  • Arizona (emergencies)
  • Arkansas (indicate a traffic hazard)
  • California (indicate a traffic hazard)
  • Delaware (indicate a traffic hazard)
  • Florida
  • Hawaii
  • Idaho (indicate a traffic hazard)
  • Illinois
  • Indiana (emergencies)
  • Iowa (indicate a traffic hazard)
  • Kansas
  • Louisiana
  • Maine (indicate a traffic hazard)
  • Maryland (emergencies)
  • Massachusetts
  • Minnesota (indicate a traffic hazard)
  • Montana (indicate a traffic hazard)
  • Nevada
  • New Mexico
  • Ohio (indicate a traffic hazard)
  • Oklahoma (emergencies and to indicate a traffic hazard)
  • Rhode Island
  • Tennessee (emergencies)
  • Virginia (indicate a traffic hazard or travelling slower than 30MPH)
  • Washington (indicate a traffic hazard)
  • West Virginia (emergencies)
  • Wisconsin (indicate a traffic hazard)

How to Use your Semi Truck Hazard Lights the Correct Way?

As we have discovered, there are several different reasons why semi trucks use their hazard lights. However, it is important to comply with the laws in your state.

If the laws state that you are not allowed to use your hazard lights while driving, we would recommend following that rule.

Reserve your hazard lights for emergencies, stopping or warning other motorists of potential dangers ahead.

Tips to Ensure that your Semi Truck Lights are Working Properly

It can be difficult to know if your hazard lights are working properly. Since you will most likely never see them from the drivers seat, you will need to do some regular checks.

Before you set off on your journey, you need to do a full check on all of your lights.

Turn the hazard lights on and do a walk around. Make sure you check all four lights to see if they are working properly.

Regular maintenance will also help to ensure that the lights are always working. You should always check them, and replace them as soon as you need to.

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