Rollover Analysis

Nathan Rose investigated and reconstructed a crash involving a Chevrolet sedan and a Honda SUV. According to the provided police report and witness statements, the Honda was heading southbound on XYZ Ave. and was then struck by the Chevrolet attempting to make a left turn from eastbound X St. At the time of the incident, a tractor trailer was also traveling down XYZ Ave. The speed limit on XYZ Ave. was 35 mph. The subject intersection is depicted in the aerial photograph below. 

The Chevrolet collided with the rear passenger side fender of the Honda, causing the Honda to overturn on its driver side and slide in a southwesterly direction to its point of rest. The Honda came to rest facing north along the west curb of XYZ Avenue, seen in the photograph below. 

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Nathan Rose and Jason Zeitler inspected, photographed, and digitally mapped the area where this crash occurred and the two subject vehicles using a FARO laser scanner and DJI Mavic 2 Pro unmanned aerial vehicle (UAF). Pix4D photogrammetry software was utilized to generate measurement points of the accident site using the aerial photographs and ground control points collected during the inspection.

The Event Data Recorder (EDR) data reported that, during the collision, the Chevrolet experienced a rearward longitudinal change in velocity of 5.0 mph. This change in velocity occurred over approximately 80 milliseconds. The Airbag Control Module (ACM) reported a lateral change in velocity from the collision of 0.6 mph, which was achieved approximately 30 milliseconds into the collision. The EDR data also included pre-collision speed data for the Chevrolet for approximately 4.5 to 5 seconds preceding the subject collision, reported at ½ second intervals. This data showed that the Chevrolet was stopped until approximately 2 seconds prior to the collision with the Honda. The Chevrolet then accelerated into the intersection and reached a speed of 11 mph approximately 0.5 seconds prior to the collision. 

Based on his inspections and photographs, Mr. Rose was able to determine that the SUV experienced a rollover event of 1 ¼ times. 

Using data collected from his inspections, Nathan Rose used an accident analysis software package called PC-Crash to simulate the subject collision. PC-Crash utilizes physics-based equations to calculate the motion of vehicles caused by driver steering, braking, and acceleration inputs, or by collision forces. The software allows the analyst to specify the vehicle and scene geometries and the roadway surface conditions, and then to simulate the motion of the vehicles. This software package is commonly and widely utilized by accident reconstructionists, law enforcement offices, insurance companies, the automotive industry, and universities to analyze vehicular collisions. The software has been validated for accident reconstruction and subjected to peer review and publication. PC-Crash has also been widely utilized and accepted in previous legal matters involving vehicular collisions. The North American distributors of PC-Crash (MEA Forensic) have compiled a list of more than 200 instances of PC-Crash being admitted for use in expert testimony in court proceedings. 

Through PC-Crash, Mr. Rose was able to determine that the actual speed of the Honda was approximately 41 mph at the time of the crash, and the speed of the Chevrolet was approximately 14 mph. Based on the speed of the SUV and the placement of the tractor trailer, Mr. Rose was able to determine the events that led to the impact.