Truck Jackknife and Underride Accident Claims 2025: Severe-Injury Liability

## Two of the Deadliest Truck Crash Types

Jackknife and underride crashes are among the most lethal events on the highway. A jackknife occurs when the trailer swings out of alignment with the tractor, sweeping across multiple lanes. An underride happens when a smaller vehicle slides beneath the trailer, often shearing off the passenger compartment. Both produce catastrophic and fatal injuries, and both raise distinctive liability questions that differ from a routine rear-end collision.

How Jackknife Crashes Happen and Who Is Responsible

A trailer jackknifes when the drive wheels lose traction and the trailer pushes the tractor sideways. The common causes point to negligence:

1. **Excessive speed for conditions**, especially on wet or icy roads.
2. **Improper braking**, where the driver brakes hard and locks the trailer.
3. **Poorly maintained brakes** that grab unevenly.
4. **Improper cargo loading** that shifts weight and destabilizes the trailer.

Liability can fall on the driver for the maneuver, the carrier for maintenance, and the loading company for an unbalanced load. Each potential defendant expands the available insurance coverage.

Underride Crashes and the Guard Standard

Underride crashes are uniquely deadly because the smaller vehicle's safety systems, designed to crush and absorb energy, are bypassed when the car slides under the trailer. Federal rules require rear underride guards, and there is growing attention to side guards. Liability theories include:

• **Defective or damaged rear guards** that failed to stop the underride.
• **Missing or non-compliant guards** on older trailers.
• **The truck's negligence** in stopping or turning across traffic.
• **Product liability** against the trailer or guard manufacturer when the equipment failed to perform.

Proving These Cases

Because the injuries are so severe, defendants fight hard. Key evidence includes:

• **The trailer and guard themselves**, preserved and inspected by engineers.
• **Maintenance and inspection records** showing the condition of brakes and guards.
• **The event data recorder** from both vehicles.
• **Reconstruction analysis** of speed, road conditions, and impact geometry.

A litigation-hold letter must go out immediately to prevent repair or scrapping of the trailer.

Compensation Ranges

These crashes sit at the catastrophic end of the spectrum:

• **Severe orthopedic and internal injuries:** 500,000 dollars and up.
• **Spinal cord injury with paralysis:** several million dollars.
• **Traumatic brain injury requiring lifetime care:** often exceeding several million dollars.
• **Wrongful death:** evaluated on survivors' losses and frequently maximizing the carrier's policy.

Step-by-Step Claim Strategy

Step one: Secure medical care and a full diagnostic workup.

Step two: Send a preservation letter for the trailer, guard, brakes, and ELD data.

Step three: Retain an engineering expert to inspect the guard and braking system before anything is altered.

Step four: Identify all defendants, including the trailer manufacturer if a guard failed.

Step five: Pursue both negligence and product-liability theories where the equipment underperformed.

FAQ

What is the difference between a jackknife and an underride crash? A jackknife is the trailer swinging out of line with the tractor. An underride is a smaller vehicle sliding beneath the trailer. They can occur together.

Can I sue the guard manufacturer? Yes, if the underride guard was defective or failed to meet federal standards, a product-liability claim may be available.

Why is preserving the trailer so important? The trailer and its guard are physical proof of the defect or failure. Once repaired or scrapped, the evidence is gone.

Are these claims worth more than typical truck crashes? Generally yes, because the injuries are catastrophic and multiple defendants and policies are often involved.