What Is a Jackknife Accident?

Posted on November 28, 2023

When a large commercial truck has an accident, the sheer size and weight of the truck results in a terrifying accident scene. If a fully loaded 18-wheeler weighing as much as 80,000 pounds is involved in an accident with an average-sized passenger vehicle weighing only 4,000 pounds, the results for the motorists in the smaller vehicle are often catastrophic. Truck accidents frequently involve collisions, rollovers, and T-bone impact accidents, but one of the most devastating truck accidents for others sharing the roadways with large trucks is a jackknife accident. This type of accident results in grave injuries to others, and is a leading cause of multi-car pileups.

Whether you’re a commercial truck driver or you often share the roadways with commercial trucks, it’s important to understand what a truck jackknife accident is, the dangers they pose to others, and how they occur.

What is a Truck Jackknife Accident?

Tractor-trailer trucks on the road are in two parts: the cab and the attached trailer.

One common type of truck accident occurs when these two parts cease moving together in unison as they are intended to—with the attached trailer directly behind the towing truck cab. There are several causes for this type of accident, but all involve the truck driver losing control of the trailer, causing it to cease its intended directory behind the cab. Instead, the trailer slides sideways on its hitch sometimes pushing the cab of the truck forward before sliding to one side and forming an L or V shape—resembling a half-open jackknife or pocket-knife.

A jackknife accident most commonly occurs in large trucks that are difficult to control and maneuver, but smaller trucks towing trailers may also experience jackknife accidents.

Tire Traction and Jackknife Accidents

In a typical jackknife accident, the truck and/or its trailer loses traction on the road and begins to slide due to a lack of friction keeping the tires firmly gripping the surface of the road while they turn. Because sliding tires can’t grip the road properly, the driver can no longer control them with the vehicle’s steering system.

When the vehicle is a commercial truck with an attached trailer, the trailer’s tires may send the trailer sliding sideways due to lack of grip. When a truck’s trailer slides out of place behind the truck, the driver can no longer drive forward but skids sideways into a crash.

Sadly, this is often a devastating accident for other drivers near the truck because a truck’s jackknife position may take up multiple lanes causing other vehicles to crash into the truck and trailer. Because these accidents happen quickly, other motorists may not have time or space on the road to avoid an impact.

Some jackknife accidents result in truck under ride accidents when a smaller vehicle collides with the side of the truck’s trailer and wedges beneath, resulting in severe head and neck trauma to passengers, often with fatal results.

Common Causes of Truck Jackknife Accidents

There are many reasons dangerous truck jackknife accidents occur, including due to driver inexperience and inclement weather conditions. Common causes of truck jackknifes include:

  • Slippery roads: snow, ice, black ice, slush, and slick rain on the road surface can cause a truck jackknife accident.
  • Improperly applied brakes: large trucks require long stopping times and inexpertly applied brakes may cause the front tires to lock up while the trailer tires keep moving, causing a jackknife position
  • Brake malfunctions: when brakes don’t operate correctly, it may cause a too-sudden stop and force the trailer into a jackknife position
  • Taking curves and making turns too quickly: this causes the trailer to swing out of alignment with the truck’s cab
  • Unbalanced loads or empty trailers: when freight isn’t properly balanced or the truck is pulling an empty trailer, the trailer may move more erratically or have less grip on the road sometimes resulting in a jackknife accident

When a truck jackknifes, it may push smaller vehicles in other lanes off the road in front of them and also cause secondary collisions from rear traffic.

Liability in Jackknife Accidents

When driver error or a defective truck part causes a devastating jackknife accident, the driver and/or trucking company may be liable for damages to injury victims as well as for property damage to other vehicles. An experienced Salt Lake City truck accident attorney from Handy & Handy can help with this type of claim.