You may have heard the term jackknifing before and you may have even seen it in real life.

When a semi-truck jackknifes, it is a scary, sometimes deadly event.

Let’s find out more about the term, what it means, and how it can be avoided.

Jackknifing is when the cab of a semi-truck and the trailer go in different directions. It is usually caused by braking too fast or poor driving conditions.

If you are in a jackknifing accident, seek medical help immediately and keep records of everything for your insurance.

What does the phrase jackknife mean?

A semi-truck has two parts to it. The cab is where the driver sits and where the engine is.

Then, the trailer is where the cargo is stored.

The cab and the trailer are attached but there is room for movement between them.

This is especially necessary when a semi-truck has to make a tight turn.

A jackknife is when the cab of the truck is pushed off to the side by the trailer.

Ultimately, you want the cab to be in control so having the trailer do the controlling is scary.

Why do trucks jackknife?

When a truck jackknifes, it means the cab was going in one direction while the truck was going in a different direction.

The result is an unsteady situation and a complete loss of control.

While the cab and the trailer can still remain upright after this happens, the action can also lead to the entire semi-truck falling on its side.

As semi-trucks weigh a lot, overturning is incredibly dangerous.

Even if the truck is still on all its wheels, it will usually end up on the side of the road or in a ditch.

Truckers will do everything they can to move the jackknifing truck to the side of the road so that it doesn’t take out any cars with it.

Common causes of jackknifing

Extreme weather conditions

Snow, sleet, and rain can cause a road to become slippery, and if a trucker isn’t prepared for this, the trailer might start to slide, which can cause the truck to jackknife.

This is often the case in higher elevations.

Many highways can have pleasant weather but as soon as you reach the summit of some mountains, there can be unexpected snow.

While trucks are required to carry chains, unexpected weather may happen and those chains might not be on the tires.

If plows haven’t been around yet to clear the snow, the conditions become even more dangerous.

Unsecured cargo

A semi-truck can carry up to 48,000 pounds of cargo. This is a huge amount and the load needs to be either packed in tight or properly secured.

If the cargo is too loose, it can slide around which can create an unequal distribution of weight.

Then, if a semi-truck is making a turn, that cargo can slide over so that there is too much weight on one side.

Gravity will then take over and cause the truck to jackknife.

The imbalance of cargo is the leading cause of a trailer that tips over.

Sudden braking

A semi-truck needs plenty of time to brake properly. The process needs to be slow and gradual, especially if the truck is still at a fast speed.

Add in the momentum of driving down a road and this braking period needs to be extended even further.

If there is too much pressure on the brakes, the back trailer won’t have enough time to keep up.

Due to the construction, a trailer can’t fall into the cab but it can swerve with extreme braking.

How to prevent jackknifing?

How to prevent jackknifing

Give trucks room

Driving is a communal activity. You can’t simply drive however fast you want because there are other vehicles on the road.

As a car driver, it is your responsibility to give semi-truck drivers the distance they need.

Crowding them can decrease the amount of time they have to break and cause drastic accidents.

When driving around a semi-truck, give plenty of warning and always use your signal.

You may be able to see the truck but it might not be able to see you.

Never pass on the right side of a semi-truck. You don’t know if they will be turning soon or even if they can see you.

Stay away from winter driving

If you don’t have to travel during a snowstorm, it’s best to stay home.

Try to make your travel plans flexible in the winter and wait until there is a period of calmer weather.

Semi-truck drivers don’t have this luxury.

They need to transport their cargo, regardless of the weather.

The emptier the road is during a snowstorm, the less risk of accidents.

Stay away from distractions

Most states now have distracted driver laws and for good reason.

Any time you are on your phone, especially if you need to look at a screen, you are more distracted.

Even something simple as eating a hamburger or drinking a coffee can be distracting.

A lot can happen if you take your eyes off the road, even for a few seconds, which can impact your reaction speed.

What to do when you get in a jackknifing accident?

See a doctor

No matter how severe your accident was, if you are ever in a jackknifing incident with a truck, always see a doctor.

Some ailments, such as whiplash, can take a day to manifest, so you want a doctor to check you over.

Seeing a doctor immediately will also provide a paper trail.

This is especially important for insurance agencies which can be meticulous about details and timelines.

Read the incident report

A trucking company will always issue an incident report. Make sure you have a copy for your insurance company.

Look for an attorney

There are some attorneys who specialize in motor vehicle accidents.

They will be able to walk you through the claim process and be an intermediator between you and the insurance company.


When a semi-truck jackknifes, this is a scary and dangerous event.

To help prevent a jackknife, semi-truck drivers should slow down and give themselves plenty of braking time.

Cars should give trucks lots of room and not be distracted drivers.