Accident reconstruction expert witness for defense opines on dual tractor trailer accident


Accident reconstruction expert witnessAn accident reconstruction expert witness for the defense advises on a case that involves a collision between two tractor trailers that were traveling on an interstate. As the trucks were side-by-side, the defendant’s truck was traveling at 63 mph in the right lane.  The plaintiff was traveling about 60 mph in the left lane. The defendant, who says he suffered a medical event, crossed into the plaintiff’s lane, sideswiping his truck and allegedly causing cervical disc herniations and a right rotator cuff tear. The plaintiff’s trailer was pushed substantially to the left across multiple lanes. He was able to straighten out and brake to a stop after the collision. Neither truck struck the center median, rolled over, or ran off the road. The plaintiff sued the offending driver and his trucking company for negligence, and hired an accident reconstruction expert with ACTAR Certification to opine on the matter.

Question(s) For Expert Witness

  • 1. How severe was the crash?
  • 2. Could the accident have caused the injuries alleged?

Expert Witness Response

Using the Engineering Dynamics Simulation Model of Automobile Collisions (EDSMAC4) accident reconstruction software, I determined not only the most likely accident scenario, but also the most severe accident scenario that could have occurred without either tractor trailer striking the center median or losing control. In my opinion, the lower end of the range was most realistic because it was consistent with the defendant passing out due to a medical event. The high end of the range was not only inconsistent with the defendant suffering a medical event, it resulted in a simulation in which the plaintiff’s trailer was pushed two full lanes to the left into the median barrier and the defendant’s tractor was steered a full lane to the left. The motion of both trucks in this particular simulation was greater than either driver testified. Even so, the impact severity predicted by the most aggressive steer simulation was very minor

In this case, I did not simply look at photographs of the damage to the tractor trailers and estimate the crash severity. I conducted a rigorous analysis involving dozens of computer simulations. Therefore, my accident reconstruction in this case is not only scientifically valid, it has a level of reliability that greatly exceeds standard methods used outside of litigation.

Additionally, relying on the medical diagnoses of the plaintiff’s treating physicians and using a biomechanical approach to injury causation analysis my primary opinion in this case is that the collision was so minor that the crash forces were within the realm of everyday experience, and therefore unlikely to cause injury.

Lastly, I drew a distinction between injuries that result from a single application of mechanical force and chronic degenerative conditions that result from physiological processes or repetitive loading. I cited several dozen biomechanical, clinical, and epidemiological peer-reviewed studies showing that intervetebral disc herniations and rotator cuff tears are relatively common in the population, are rarely caused by trauma, and are strongly associated with genetic and occupational factors. Given the extremely minor nature of the collision, I concluded that the plaintiff’s cervical disc herniations and right rotator cuff tear were more likely degenerative in origin rather than traumatic. All of my opinions are based on a reliable and well-accepted scientific methodology that has been extensively tested and documented in the peer-reviewed literature.

The expert has degrees in bio-mechanical engineering and has performed numerous full-scale vehicle-to-vehicle crash tests involving sideswipes. He is a biomedical engineering professor and author or published studies.

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