A “jackknife” accident happens when a tractor-trailer’s trailer swings out and folds toward the cab, forming a V-shape that resembles a folding pocketknife. It’s one of the most dangerous events on Texas highways — a jackknifing semi can span multiple lanes in seconds, and the crashes that follow are frequently multi-vehicle pileups with severe injuries.

If you’ve been hurt in one, the first question is usually the same one we hear in nearly every 18-wheeler accident case we handle: whose fault was it? The answer is less obvious than it looks.

What Causes a Truck to Jackknife

Jackknifing happens when the trailer loses traction relative to the cab and swings out of alignment. The most common triggers include:

• Sudden or hard braking, especially on wet, icy, or oil-slicked pavement
• Empty or improperly loaded trailers, which have less weight over the rear axles and lose traction more easily
• Excessive speed for road conditions, particularly heading into curves or highway merges
• Mechanical failure, including worn brakes, brake imbalance between the tractor and trailer, or tire blowouts
• Driver inexperience or fatigue, leading to overcorrection when the trailer starts to sway

Texas’s mix of high-speed interstate corridors, sudden downpours, and heavy commercial freight traffic through the Dallas–Fort Worth area makes jackknife accidents a recurring problem, particularly on I-35, I-20, and I-30.

Is Jackknifing Automatically the Driver’s Fault?

Not automatically — and this is where a lot of injury claims go wrong. Texas is a modified comparative negligence state, meaning fault can be shared, and a jury or insurance adjuster has to allocate a percentage of responsibility to each party. In jackknife cases, that responsibility can fall on more than just the driver:

• The driver — if braking was excessive, speed was unsafe for conditions, or reaction to a hazard was mishandled
• The trucking company — if driver fatigue rules were violated, or the driver was pushed to run in unsafe conditions
• A maintenance contractor or the carrier itself — if worn brakes or a mechanical defect contributed to the loss of control
• A loading company — if improper weight distribution made the trailer unstable
• A parts manufacturer — in cases involving defective brake or trailer hitch components

Because jackknife accidents often stem from a combination of factors — a driver braking hard on wet pavement while hauling a poorly loaded trailer, for example — building a full liability picture usually requires more than the police report. It typically involves the truck’s electronic logging device (ELD) data, maintenance records, and the carrier’s driver qualification and hours-of-service files.

Common Injuries in Jackknife Accidents

Because a jackknifing trailer can strike multiple vehicles or block several lanes at once, injuries tend to be severe:

• Traumatic brain injuries from high-speed impact
• Spinal cord injuries and paralysis
• Crush injuries from a trailer striking a passenger vehicle
• Multi-vehicle pileup trauma, including secondary collisions
• Fatalities, particularly in high-speed highway settings

The scale of these injuries is one reason jackknife claims often involve significantly higher damages than a standard rear-end collision — and why insurers tend to fight liability more aggressively.

Steps to Take After a Jackknife Accident in Texas

• Preserve the scene if you’re able to — photos of skid marks, trailer position, and road conditions are critical and often disappear once traffic clears.
• Request the crash report through the Texas Department of Public Safety.
• Don’t assume fault based on appearance — a dramatic-looking jackknife doesn’t automatically mean clear driver negligence.
• Get medical evaluation immediately, even for injuries that seem minor at first — trauma from high-impact crashes isn’t always immediately apparent.
• Avoid early settlement offers from the trucking company’s insurer before liability and the full extent of injuries are established.

Talk to a Dallas Truck Accident Attorney

Jackknife accidents involve technical evidence — ELD data, brake maintenance logs, weight distribution records — that most people don’t know to request, and that trucking companies aren’t required to hand over voluntarily. If you’ve been injured in a jackknife accident anywhere in the Dallas area, speak with a dallas truck accident attorney before accepting any settlement offer, so the full picture of liability can be established before evidence disappears.

This article is for informational purposes and does not constitute legal advice. Every case is different — contact our office to discuss the specific facts of your accident.