Journal of the National Academy of Forensic Engineers

Subjects’ Ability to Characterize g’s in Relation to Activities of Daily Living

William Lee — 2024-07-14

The amount of force associated with a specific activity or event often utilizes g’s (g-force) and the unit of force. In litigation, biomechanics forensic experts provide general causation analysis of injury events, referencing the g’s of the event and often the g’s associated with Activities of Daily Living (ADLs). It is assumed that jurors will understand and correctly interpret any presented g values. This research explored the validity of this assumption. A survey instrument was employed that included 610 subjects to probe an individual’s understanding of what g’s are and their beliefs of the associated magnitude of ADL g’s. The results indicated that most adults have a limited understanding of g’s, often holding incorrect beliefs. For example, many believe they do not experience 2 or 3 g’s during daily activities. Therefore, it is useful for the engineering expert to frame g-based analysis with references to ADLs, providing individuals (and jurors) with a proper framework to understand the analysis results. Without such reference points, jurors may misunderstand — and attorneys can misrepresent — the meaning of any g’s associated with the specific case analysis.

Distracted Driving: Determining Cell Phone Usage from Forensic Cellular Records

Mark McFarland — 2024-07-14

This paper presents an analysis of an alleged texting-while-driving collision case involving cellular call records. The plaintiff’s expert, unfamiliar with cellular networks, made serious errors in interpreting the cellular records, which resulted in a mischaracterization of the defendant’s cell phone usage at the time of the collision. Thus, the plaintiff’s expert could not support his opinion that the defendant was using her phone at the time of the collision. The expert made three critical mistakes interpreting the cellular records — mistakes that are commonly made by analysts who are unfamiliar with the design and operation of cellular phone networks. This paper explains the common mistakes and faulty assumptions behind them. The proper analysis methods of a qualified engineer with an understanding of cellular networks are also presented.

Forensic Investigations of Low-Clamp-Force Type Wheel Separations

Mark Bailey — 2024-07-14

Wheel separations are a common non-operator cause of damage and injury in road transport systems. Forensic investigators are often engaged to determine why a wheel separated from a moving vehicle. In 100 investigations, the authors observed wheel separations due to axle, bearing, or fastener system failures. Fastener system failures dominate, and the authors show that low fastener clamp force is their necessary and sufficient condition. Examples of physical evidence of low fastener clamp force commonly found in forensic investigations are presented. The reasons for low fastener clamp force are explored using known wheel installation-to-separation times and distances, torque audits, and interface corrosion. From these, it is often possible to form a sound explanation for a low-clamp-force type wheel separation. Finally, wheel nut re-torquing is identified as a probable effective measure in preventing low-clamp-force type wheel separations.

FE Evaluation of Pedestrian and Worker Fall Incidents — the Evolution of Analysis Techniques and Safety Requirements

Christopher Shiver — 2024-07-14

Fall injury and fatality claims and legal cases involving ordinary pedestrians as well as employees/contractors at work sites have increased dramatically over the course of the author’s 43-year engineering career. As a result, forensic engineers are frequently being contacted by insurers and attorneys to analyze these incidents. The need is to determine probable cause(s) and ascertain as to whether location features were designed, constructed, installed, manufactured, and/or maintained in accordance with the standard of care, including requirements specified in applicable codes and standards. The proper contemporary analysis techniques for these incidents are addressed in this paper as well as what constitutes proper basis for establishing a standard of care for involved installations and/or equipment. It will also expand on and update information provided in approximately two dozen past NAFE papers on various aspects of fall incident analysis, most of which are more than 10 to 30 years old.