Comparison of Restraint System Marks with Proper and Improper Belt Usage

Accident investigators are often required to determine if an occupant was using a seat belt during a collision. Substantial research has been conducted on the types of physical evidence generated on a seat belt by occupant loading during a collision. However, very little research has been conducted concerning the characteristics of physical evidence that is created when an occupant uses their seat belt improperly. Case studies with misused seat belts were reviewed showing tell-tales of atypical or improper restraint usage. Occupants also experienced injuries consistent with greater excursion and contact with vehicle interior surfaces. To compare the physical evidence of properly and improperly used restraints, automotive frontal sled tests were conducted with matched pairs of anthropomorphic test devices (ATD) with seat belts used both correctly and incorrectly. When the seat belt was used improperly, distinctly different marks were observed. Improper seat belt usage also produced less effective restraint geometry and caused the ATD to experience greater forward excursion.