Biomechanical Analysis of Occupant Kinematics: Interpretation of Witness Marks

Understanding the occupant kinematics associated with an automotive accident is essential to evaluating injury causation and can lead to improved design of vehicles and restraint systems. Biomechanical analysis can be undertaken with knowledge of the accident reconstruction, that is, velocities and trajectories of the involved vehicle or vehicles, as well as the results of a detailed vehicle inspection and evaluation of other physical and photographic evidence. Evidence can be incomplete, seemingly contradictory, or compromised by the passage of time, and the biomechanical engineer must seek an explanation that is consistent with all that is known. Sometimes a physical examination of the accident vehicle provides a vivid understanding of injury causation. At other times the information obtained from the vehicle is understood only in the context of injuries sustained, witness statements, and/or information derived from other sources. We explain a methodology for conduct of a physical inspection of an accident vehicle to develop insight to be used in conjunction with information from other sources to elicit a clear and complete understanding of injury causation. We specify common and less common “witness marks” that are examined to develop constraints on possible occupant kinematics. Selected case studies highlight the importance of a careful inspection and suggest specific applications to accident scenarios.