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Trailer Jackknife Incidents: The Most Common Causes and How to Avoid Them

Posted on September 12, 2023

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Trailer jackknifing is a term that might sound unfamiliar to many, but for truck drivers and road safety experts, it’s a well-known and daunting phenomenon. Envision a tractor-trailer rig on the highway. Ideally, both the tractor (the front part with the engine and the driver) and the trailer (the larger section carrying the cargo) move seamlessly in tandem. However, during a jackknife incident, the trailer skews to one side, forming an acute angle with the tractor, much like a folding pocket knife. This not only endangers the driver but also poses a significant threat to other motorists on the road. Understanding the causes of trailer jackknifing and the measures to prevent it is of paramount importance. Whether you’re a seasoned driver, a novice, or someone who shares the road with these massive vehicles, having knowledge about jackknifing can be a lifesaver.

In this article, we’ll explore the most common causes of a trailer jackknife, delve deep into the mechanics of how it happens, and provide insights on how to avoid such incidents. So, let’s embark on this informational journey and ensure safer roads for all.

What causes a trailer to jackknife?

Jackknifing is a complex event that can arise from a multitude of factors. At its core, a jackknife happens when the trailer that a truck is towing loses traction and swings out to the side, resulting in it facing a direction opposite or at a sharp angle to the truck’s motion. This can happen in the blink of an eye, making it a dangerous situation for both the truck driver and other vehicles nearby.

  • Loss of Traction: The most immediate cause is a sudden loss of traction, which can happen due to slick roads, sudden maneuvers, or abrupt braking. When the wheels of the trailer or tractor lock up, it can initiate a skid, which, if not corrected promptly, can lead to the trailer swinging out.
  • Speed and Momentum: The sheer size and weight of a fully loaded trailer mean that it carries a significant amount of momentum. If a driver takes a curve too fast or brakes suddenly at high speeds, it can cause the trailer to swing out, especially if the cargo is not evenly distributed.
  • Improper Braking: In situations where a driver applies more brake force to the trailer than to the tractor, the trailer can begin to skid. Modern trucks often come equipped with anti-lock brake systems (ABS) to mitigate this, but older models or those without ABS can be especially prone to this.
  • Uneven Cargo Load: When the cargo in a trailer is not loaded evenly or is not secured properly, it can shift during transit. A sudden shift in weight can throw off the balance of the trailer, especially during turns or sudden stops, leading to a potential jackknife.

It’s important to note that while these are some of the primary causes, jackknifing can also be influenced by external factors like road conditions, other vehicles’ actions, and even the design of the truck and trailer. In the upcoming sections, we’ll explore more about these factors and the intricacies of how jackknifing occurs.

The Three Basic Causes of Skidding and Jackknifing

When it comes to trailer jackknifing, it’s often intertwined with the broader phenomenon of skidding. Skidding essentially refers to the loss of grip between the vehicle’s tires and the road surface. Let’s break down the three fundamental reasons behind skidding and, subsequently, jackknifing:

Mechanical Failures

  • Brake Issues: Malfunctioning brakes or brakes that aren’t properly balanced between the tractor and the trailer can result in uneven braking. This disparity can make the trailer skid and potentially jackknife.
  • Tire Problems: Worn out tires lacking sufficient tread, or tires that are improperly inflated, compromise the grip on the road. This reduced traction, especially on wet or icy roads, makes skidding more likely.
  • Suspension System Failures: A suspension system in disrepair can lead to uneven weight distribution, thereby affecting stability and increasing the risk of a skid.

Driver Errors

  • Abrupt Maneuvers: Sudden steering actions, especially at high speeds, can upset the balance of a heavy trailer, initiating a skid.
  • Improper Speed for Conditions: Driving too fast for road conditions, especially on curves or slippery surfaces, significantly elevates the risk of skidding.
  • Lack of Awareness: Being unaware of the weight distribution inside the trailer, or not accounting for the trailer’s length and weight during maneuvers, can lead to mistakes that cause skids and jackknifes.

Environmental Factors

  • Road Conditions: Wet, icy, or oily surfaces significantly decrease tire traction. Rain, snow, or even leaves can render a road surface treacherous.
  • Visibility: Fog, heavy rain, or other conditions that reduce visibility can lead to sudden reactions or misjudgments by the driver, resulting in skids.
  • Unexpected Obstacles: Objects or animals suddenly appearing on the road can cause a driver to react abruptly, initiating a skid.

Understanding the primary causes behind skidding is essential in grasping the mechanics of jackknifing. By addressing these core issues, one can mitigate the risk of a trailer jackknife incident and promote safer driving habits.

Delving Deeper: How Do Jackknives Happen?

While we’ve discussed the root causes that may lead to a trailer skidding or jackknifing, it’s crucial to understand the dynamics and physics behind these incidents to fully grasp their severity.

The Physics of Motion

  • Centrifugal Force: When a truck makes a turn, the centrifugal force pushes the trailer outwards. If the force is strong enough and not counteracted appropriately, it can cause the trailer to swing out.
  • Inertia: An object in motion tends to stay in motion. When a driver brakes abruptly, the tractor might slow down or stop, but the heavy trailer, due to its inertia, wants to keep moving. This discrepancy can cause the trailer to swing out, leading to a jackknife.

Dynamics of a Moving Trailer

  • Pivot Point: The point where the tractor and trailer are hitched is essentially a pivot point. When the trailer begins to skid, it will often swing out around this pivot, leading to the characteristic “jackknife” angle.
  • Length and Weight: Longer trailers have a more significant swinging motion when they begin to jackknife. Similarly, the weight of the trailer influences how quickly and severely a jackknife can occur.

Reaction Time and Correction

  • Delayed Reactions: A split second can make all the difference. The time it takes for a driver to realize a skid is happening and then to respond appropriately can determine the severity of the jackknife.
  • Overcorrection: Sometimes, in an attempt to control a skidding trailer, a driver might oversteer or brake too hard. This overcorrection can exacerbate the jackknife or even lead to a rollover.

In essence, jackknifing is a confluence of physical forces, vehicle dynamics, and human reactions. It’s a situation where the trailer, for various reasons, decides to take a different path than the one the tractor and driver intended. Recognizing the early signs and understanding the mechanics of a jackknife can aid drivers in preventing a full-blown incident.

Which Trailer is Most Likely to Jackknife?

The world of trucking is diverse, with a multitude of trailer types designed for various purposes. However, not all trailers are created equal when it comes to the risk of jackknifing. Let’s explore the factors that make certain trailers more susceptible:

Length of the Trailer

Shorter Trailers: Surprisingly, shorter trailers can be more prone to jackknifing than their longer counterparts. This is because they can change direction faster than longer trailers, giving drivers less time to react and correct the situation.

Empty vs. Loaded Trailers

Empty Trailers: While it might seem counterintuitive, an empty or lightly-loaded trailer is often more susceptible to jackknifing than a fully loaded one. This is because the reduced weight results in less tire traction on the road. When a driver brakes abruptly, the wheels of an empty trailer are more likely to lock up and skid.

Type of Cargo

Liquid Cargo: Trailers carrying liquids, like tankers, have a unique challenge. Liquids can slosh around, and if they start moving to one side, they can destabilize the trailer. This phenomenon, known as “liquid surge,” can increase the risk of jackknifing, especially during sudden stops or turns.

Design and Maintenance

  • Age and Wear: Older trailers, or those not properly maintained, might have compromised braking systems or worn-out tires, both of which can increase the risk of a jackknife.
  • Suspension Design: Trailers with poor suspension designs or systems can distribute weight unevenly, making them more prone to skidding and subsequent jackknifing.

Environmental Suitability

Specialized Trailers: Some trailers are designed for specific environments, like off-road conditions. Using them on regular highways without appropriate modifications can increase their jackknife risk. While these factors can influence a trailer’s susceptibility, it’s essential to understand that any trailer, if not handled correctly or if driven under adverse conditions, can jackknife. Awareness, proper training, and the right equipment go a long way in preventing these incidents.

Prevention: How Do You Avoid Jackknifing a Trailer?

Knowing the causes and mechanics of jackknifing is only half the battle; the ultimate goal is prevention. Ensuring that both the driver and the trailer are prepared can significantly reduce the risk of a jackknife incident. Here are some vital preventative measures:

Safe Driving Practices

  • Speed Control: Always drive at speeds suitable for road conditions, especially when taking turns. Reducing speed during adverse weather conditions can also help prevent skids.
  • Gradual Braking: Apply brakes slowly and steadily. Avoid slamming on the brakes unless it’s an emergency.
  • Stay Alert: Be aware of your surroundings. This includes keeping a safe distance from other vehicles, anticipating turns, and being ready for sudden obstacles.

Equipment Checks and Maintenance

  • Regular Inspections: Ensure that the braking system, tires, and other essential components are in top condition.
  • Anti-lock Braking System (ABS): Modern trailers often come equipped with ABS, which helps prevent wheel lock-up during sudden braking.
  • Tire Maintenance: Regularly check tire pressure and tread depth. Replace worn-out tires promptly.

Cargo Loading

  • Even Distribution: Make sure cargo is loaded evenly across the trailer. This ensures balanced weight distribution, reducing the risk of jackknifing during maneuvers.
  • Securing Cargo: Securely tie down cargo to prevent it from shifting, which can destabilize the trailer.

Training and Awareness

  • Professional Training: Especially for new drivers, professional training can provide the skills needed to handle unexpected situations and recognize the early signs of a skid.
  • Stay Informed: Understand the specific risks associated with the type of trailer you’re towing. For instance, if you’re hauling liquid cargo, be aware of the risks of liquid surge.

Environmental Awareness

  • Monitor Weather Conditions: Be extra cautious during rain, snow, or icy conditions. If possible, avoid driving during extreme weather.
  • Road Knowledge: If you’re familiar with the roads you’re traveling on, you can anticipate challenging curves or known slippery spots.

Prevention is a mix of awareness, maintenance, and skill. By prioritizing safety and ensuring both the driver and the equipment are in their best states, the risks of jackknifing can be substantially reduced.

Understanding the Consequences: Is Jackknifing a Trailer Bad?

To some, the term “jackknife” might seem innocuous, perhaps even reminiscent of a pocket tool. However, in the realm of trucking and trailers, a jackknife is far from benign. Understanding its consequences helps underscore the importance of prevention.

Safety Hazards

  • Accidents and Collisions: When a trailer jackknifes, it can quickly span multiple lanes, leading to collisions with other vehicles. In severe cases, these accidents can result in fatalities.
  • Rollovers: A jackknifing trailer can lead to the tractor rolling over, especially if the driver tries to overcorrect or if the incident occurs at high speeds.
  • Hazard to the Driver: The sudden force of a jackknife can cause injury to the driver, especially if it results in a collision or rollover.

Economic Consequences

  • Damage to the Trailer and Cargo: Jackknifing can lead to significant damage to both the trailer and its cargo. This can result in economic losses, especially if the cargo is of high value or perishable.
  • Road Closures: Severe jackknife incidents might require closing down lanes or entire highways, leading to traffic disruptions and economic implications for businesses relying on timely deliveries.

Reputational Impacts

  • Company Image: Frequent jackknife incidents can tarnish the reputation of a trucking company, making it harder to secure contracts or leading to increased insurance premiums.
  • Public Perception: A high-profile jackknife accident, especially if it results in casualties, can lead to negative public sentiment and increased scrutiny of the trucking industry.

In summary, yes, jackknifing a trailer is bad. The repercussions can be far-reaching, affecting the safety of many, the economic stability of businesses, and the reputation of the trucking industry. It underscores the importance of taking all possible measures to prevent such incidents.

Further Insights: Jackknifing During Specific Scenarios

There are certain scenarios and questions that truck drivers and companies often wonder about when it comes to jackknifing. Addressing these can provide a more comprehensive understanding of the phenomenon.

Can You Jackknife a Trailer While Backing Up?

Yes, it’s possible, and it’s a common scenario, especially for inexperienced drivers or in tight spaces. When backing up, if the angle between the tractor and the trailer becomes too sharp, it can result in a jackknife situation. Regular practice, using mirrors effectively, and having a spotter can help reduce this risk.

When is Jackknifing Most Likely to Occur?

Jackknifing is most likely to occur during sudden braking or abrupt maneuvers, especially on slippery roads. Situations like downhill drives with heavy loads, sharp turns at high speeds, or sudden reactions to road obstacles can precipitate a jackknife. Adverse weather conditions, such as rain, snow, or ice, heighten the risk.

Are Trailers Most Likely to Jackknife When They Are Fully Loaded?

Interestingly, while one might assume that a heavier load would increase the risk, it’s often the opposite. Empty or lightly-loaded trailers are generally more prone to jackknifing. This is because they have less traction due to the reduced weight pressing the tires against the road. A fully loaded trailer, assuming the weight is distributed evenly, often has better road grip, making it less susceptible. By understanding these specific scenarios, drivers and trucking companies can be better equipped to handle them and take the necessary precautions.


What exactly does it mean for a trailer to “jackknife”?

A jackknife occurs when a truck’s cab and its trailer fold in on each other at a sharp angle, similar to the way a folding pocket knife looks when it’s being closed. This typically happens when the trailer skids, causing it to move at a different angle than the cab.

Why are empty trailers more prone to jackknifing than fully loaded ones?

Empty or lightly-loaded trailers have less weight pressing the tires against the road, which can reduce their traction. When a driver brakes suddenly, the wheels of an empty trailer are more likely to lock up and skid, increasing the risk of jackknifing.

Is it possible to recover from a jackknife situation while it’s happening?

It can be challenging to recover from a jackknife once it starts, especially at high speeds. However, releasing the brakes, straightening the steering wheel, and trying to accelerate slightly might help in some situations. Proper training and experience are crucial for handling such emergencies.

Are certain weather conditions more conducive to jackknife incidents?

Yes, adverse weather conditions like rain, snow, or ice can make roads slippery, increasing the risk of skidding and jackknifing. Drivers should exercise extra caution and adjust their driving techniques during such conditions.

How can regular vehicle drivers help reduce the risk of jackknifing for trucks on the road?

Giving trucks ample space, avoiding sudden stops in front of them, and understanding their blind spots can help. Truck drivers often need more time to react due to the size and weight of their vehicles, so being considerate and aware can reduce risks for everyone on the road.


Trailer jackknife incidents are not only alarming for drivers but can have profound consequences for everyone on the road. By understanding the mechanics, causes, and scenarios where jackknifing can occur, we arm ourselves with the knowledge to prevent such incidents. Moreover, prevention is not solely the responsibility of the truck driver. Everyone can play a role by staying educated, giving trucks ample space on the roads, and promoting safe driving practices. Companies, too, should invest in proper training for their drivers, ensuring their fleet is in top condition, and fostering a culture of safety. For those who find themselves involved in a jackknife incident or any truck-related accident, it’s crucial to seek guidance. Legal complexities can arise, and having experienced truck accident lawyers by your side can make all the difference. At Drake Injury Lawyers, we’re committed to ensuring that victims of such incidents get the representation and support they deserve. If you or a loved one needs assistance, don’t hesitate to reach out at 205-859-2236. Remember, safe roads benefit us all, and together, we can make a difference.

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