A jackknife truck accident happens in seconds, but the damage it leaves behind can affect victims for years. When a tractor-trailer’s trailer swings out and forms an angle with the cab instead of tracking straight behind it, the rig loses its ability to steer or stop predictably. The result is often a multi-vehicle collision that closes a highway for hours and leaves serious injuries in its wake.
What Is a Jackknife Truck Accident?
A tractor-trailer is built as two connected units joined at a pivot point, the fifth wheel. Under normal conditions, the trailer follows directly behind the cab in a straight line. In a jackknife, the trailer swings out to one side, forming a V or L shape with the tractor, similar to the folding motion of a pocketknife. Once the trailer begins to slide, the driver typically has little ability to correct the rig’s path, and the trailer can continue swinging until it is perpendicular to the cab, blocking multiple lanes.
Jackknifing is most likely when the trailer’s wheels lose traction while the tractor’s wheels retain it, or the reverse. That imbalance in traction is what sends the trailer sideways.
Common Causes of Jackknifing
Jackknife incidents rarely happen without a contributing factor. Investigators typically look at some combination of the following:
- Hard or improper braking: Slamming the brakes, or braking in a way that does not account for the trailer’s weight and momentum, can cause the trailer wheels to lock and slide.
- Speeding for conditions: A speed that is legal on a dry, empty highway can be too fast for rain, fog, traffic congestion, or a downhill grade.
- Slippery roads: Rain, snow, ice, and even road oil reduce the traction a loaded trailer needs to track behind the cab under braking.
- Poorly maintained or unbalanced brakes: If the tractor’s brakes engage faster or harder than the trailer’s, or the trailer’s brakes are worn or out of adjustment, the mismatch can trigger a slide.
- Unsecured or shifting loads: Cargo that is not properly secured can shift the trailer’s center of gravity mid-drive, making it prone to swinging out under braking.
- Driver inexperience: Operating a loaded tractor-trailer in adverse weather or dense traffic requires skills, including staged braking, that inexperienced drivers may not have developed.
These causes often overlap. A driver unfamiliar with a route may brake too hard on a wet downhill approach, while the carrier’s maintenance program has already left the trailer’s brakes out of adjustment.
Why Jackknife Crashes Cause Severe Multi-Vehicle Collisions
A jackknifed trailer does not simply stop. It slides across lanes at an angle that leaves surrounding drivers little time to react. Because the trailer can span two or three lanes once it swings out, vehicles traveling alongside or behind the truck have little room to avoid it. A loaded trailer can also tip over during the slide, spilling cargo onto the roadway and creating hazards for vehicles arriving on scene afterward.
The size and weight difference between a tractor-trailer and a passenger vehicle means even a lower-speed jackknife can produce catastrophic injuries: spinal cord damage, traumatic brain injury, crush injuries, and fatalities are common outcomes. Chain-reaction collisions are also common, since a jackknifed rig can block all lanes of a highway with little warning to approaching traffic.
Investigating Liability After a Jackknife Truck Accident
Liability in a jackknife case depends on identifying what caused the trailer to lose traction and slide, and that requires a focused evidence investigation. A truck injury lawyer typically pursues several categories of evidence:
- Electronic logging device (ELD) data: ELD and engine control module data can show the truck’s speed, braking inputs, and hours of service in the moments before the crash.
- Brake maintenance and inspection records: Federal regulations require regular brake inspections and maintenance logs. Records showing deferred repairs or unbalanced brake adjustment between tractor and trailer can establish a maintenance failure.
- Weather and roadway conditions: Weather service data, road maintenance logs, and traffic camera footage help establish whether conditions were foreseeable and whether the driver adjusted speed accordingly.
- Cargo loading records: Bills of lading and loading documentation can reveal whether a shifting or improperly secured load contributed to the trailer’s instability.
- Driver qualification and training files: A driver’s experience and disciplinary history can be relevant when inexperience contributed to the crash.
Liability can extend beyond the driver to the trucking company, a maintenance contractor, or a cargo loading company, depending on what the evidence shows. Preserving ELD data and maintenance records quickly matters, since carriers are not required to retain this evidence indefinitely. Massachusetts law generally allows three years from the date of the crash to file a personal injury claim under G.L. c. 260, section 2A, but evidence can disappear well before that deadline if it is not requested early.
Anyone reviewing the facts of a jackknife collision should also understand why truck cases are different from ordinary car crash claims, and how a tractor-trailer crash lawyer approaches the evidence unique to commercial vehicles. More on how these claims are built and pursued is available at truck crash claims.
Speak With a Truck Injury Lawyer About a Jackknife Crash
Jackknife crashes involve technical evidence that is time-sensitive and easy to lose once a carrier’s routine record retention cycle passes. A truck injury lawyer at Scalli Murphy Law, P.C. represents injured clients statewide across Massachusetts. Call 978-347-4400 or request a free case review to discuss what happened and what evidence needs to be preserved.