Why Did The Vehicle Cross the Centerline? Was It a Criminal Action?


Steven M. Schorr, PE ::::

Case Synopsis: A pickup truck traveling northbound on a two-lane, two-direction roadway was approaching a slight curve to the right when the vehicle failed to remain in the northbound lane, crossed the centerline, and entered the southbound lane.  Yaw marks (tire marks indicating the wheels were rotating but sliding sideways) were present in the southbound lane, consistent with the pickup truck operator attempting to steer back to the right prior to contacting southbound vehicles.  The pickup truck operator claimed he passed out due to medical reasons and when he came to, he was in the opposite lane and attempted to steer back to the right.  The Criminal Complaint versus the pickup truck operator claimed that the vehicle operator failed to negotiate the curve in the roadway due to excessive vehicle speed as well as the presence of alcohol in his blood.

Expert Analysis: The analysis of the available physical evidence established the speed of the pickup truck based on the yaw marks left on the roadway. The calculated speed was consistent with a vehicle traveling at, or around, the speed limit and, as such, excessive speed was not the reason why the vehicle crossed the centerline.  The analysis also indicated that the location along the curve where the vehicle crossed the centerline was consistent with the beginning of the curve.  That is, the physical evidence established that prior to the collision, the pickup truck was traveling properly within its northbound lane but, when it reached the curve, the vehicle never negotiated the right-hand turn and simply continued straight into the southbound lane. The physical evidence provided no data indicating the pickup truck operator took any action prior to entering the southbound lane.   As such, the physical evidence (or the lack of physical evidence) was consistent with the pickup truck operator’s testimony that he was not conscious as he crossed the centerline.  The physical evidence (the yaw marks) was consistent that once the pickup truck was over the centerline, the operator did take evasive action by steering back to the right.  In contrast to the Criminal Complaint assertion that the presence of alcohol in the pickup truck operator’s system caused him to fail to negotiate the curve, medical testimony was utilized to show the pickup truck operator had a specific medical condition which would be consistent with him “passing out”, as he testified.

Result: The case went to trial and the jury found the defendant driver not guilty of the most serious charges against him.

Steven M. Schorr, PE, is President of DJS Associates and can be reached via email at experts@forensicDJS.com or via phone at 215-659-2010.

Categories: Case Studies


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