The Physics of Jackknifing: Calculating Speed from Trailer Pivot Marks

A jackknife accident occurs when the drive wheels of the tractor lock up, causing the trailer to swing forward and pivot until it faces the tractor. On Route 18 and the NJ Turnpike, these events are often blamed on “unavoidable road conditions.”

Kinetic Analysis vs. Driver Testimony

Trucking companies will often claim the driver was traveling at a safe speed and hit a patch of oil or black ice. Our kinetic analysis often proves otherwise. By measuring the length and angle of pivot marks on the asphalt, our engineers can calculate:

1. Approach Speed: The velocity of the vehicle prior to brake initiation.
2. Brake Bias: Whether the trailer’s braking system was improperly maintained, leading to unequal pressure.
3. Weight Distribution: How an improperly secured load contributed to the trailer’s centrifugal swing.

Proving Negligence in New Jersey

In NJ courts, proving that a jackknife was a result of driver speed-for-conditions or maintenance failure is the difference between a minor settlement and a multi-million dollar verdict.