R. Scott King, BSME, Automotive / Mechanical Engineer ::::
Case Synopsis: A commercial vehicle owner-operator, while monitoring a common “trucker’s” CB channel, heard a report of a truck that had lost its wheel and caused a multi-vehicle collision. Realizing he had just traveled through the reported incident area but did not witness the incident, the driver pulled over to examine his vehicle. He discovered that a pair of his tractor’s tandem wheels was missing and he was probably the subject of the CB report. The operator returned to the scene to identify himself, and assist with the investigation.
The incident occurred within a densely wooded area. The police and other investigators searched the area, but only located one of the truck’s tandem wheel assemblies. Based on this, the owner-operator theorized that the missing tandem wheel was actually not installed on the truck when its companion wheel detached, and that the missing wheel had been stolen while his rig was parked at a rest stop just a few miles up the road. The driver’s insurance carrier retained an engineer to assist with the investigation to determine whether the driver’s theory made sense.
Analysis: The ensuing investigation revealed that the wheel recovered at the scene was indeed an outer tandem wheel from the suspected truck. Further, the wheel possessed telltale marks demonstrating it had been installed on the truck with all 10 lug nuts in place; however, these marks also indicated the lug nuts had progressively loosened over time, resulting in a characteristic elongation of the lug stud holes. Moreover, an interview with the driver revealed that he had installed two new tires at the incident wheel location just one week before the incident.
The physical evidence revealed that the incident wheel was loosely attached to the vehicle with all its required lug nuts long enough to cause the telltale markings. If the driver’s theory that someone stole the companion tire just prior to the incident was true, then the thief would have had to remove both tandem wheels, steal only the inner wheel, replace the outer wheel, and reattach all 10 lug nuts. Although the inner wheel was never found, the physical evidence demonstrated a scenario that the insurance carrier simply could not sustain; particularly knowing the driver installed the wheels just one week earlier.
Result: The case settled without litigation
For additional information, contact R. Scott King at experts@forensicDJS.com