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Three years of data from the Large Truck Crash Causation Study (LTCCS) were analyzed to identify accidents involving heavy trucks (GVWR >10,000 lbs.). Risk of rollover and ejection was determined as well as belt usage rates. Risk of ejection was also analyzed based on rollover status and belt use. The Abbreviated Injury Scale (AIS) was used as an injury rating system for the involved vehicle occupants. These data were further analyzed to determine injury distribution based on factors such as crash type, ejection, and restraint system use. The maximum AIS score (MAIS) was analyzed and each body region (head, face, spine, thorax, abdomen, upper extremity, and lower extremity) was considered for an AIS score of three or greater (AIS 3+). The majority of heavy truck occupants in this study were belted (71%), only 2.5% of occupants were completely or partially ejected, and 28% experienced a rollover event.

The risk of sustaining injury in rear impact collisions is correlated to collision severity as well as other factors such as restraint usage. The most recent National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) data available (1997 to 2011) were analyzed to identify accidents involving passenger vehicles that have experienced an impact with a principal direction of force (PDOF) between 5:00 and 7:00, indicating a rear impact collision. The Abbreviated Injury Scale (AIS) was used as an injury rating system for the involved vehicle occupants who were at least sixteen years old and were seated in the outboard seating positions of the front row. These data were further analyzed to determine injury risk based on resultant delta-V and restraint system use. Each body region (head, spine, thorax, abdomen, upper extremity, and lower extremity) was considered separately.

It is well known from field accident studies and crash testing that seatbelts provide considerable benefit to occupants in rollover crashes; however, a small fraction of belted occupants still sustain serious and severe neck injuries. The mechanism of these neck injuries is generated by torso augmentation (diving), where the head becomes constrained while the torso continues to move toward the constrained head causing injurious compressive neck loading. This type of neck loading can occur in belted occupants when the head is in contact with, or in close proximity to, the roof interior when the inverted vehicle impacts the ground. Consequently, understanding the nature and extent of head excursion has long been an objective of researchers studying the behavior of occupants in rollovers.

Although most of the research on vehicular rear impacts has focused on the neck, there is increasing current concern about the lumbar spine. Spinal bending superimposed with sudden spinal compression has been suggested as a mechanism of creating acute herniations on the rare occasion in which low back pain associated with an intervertebral disc herniation was reported. During automotive rear-impacts, the vehicle accelerations are directed anteriorly, and the seat backs deflect posteriorly. In vehicle seats equipped with floor-mounted seatbelt restraints, the pelvis is restrained by the seatback and seatbelt, while the torso ramps upward and rearward on the seatback during the rearward motion, producing tension in the lumbar spine. However, in an all-belts-to-seat arrangement, the lumbar spines may experience overall compressive and bending loads.

Debate surrounds the utility of the Biofidelic Rear Impact Dummy (BioRID) anthropomorphic test device (ATD) for providing meaningful biomechanical metrics during rear impact and the appropriate criteria for interpreting the ATD response. In the current study, we performed a comparison of the kinematic and kinetic responses of the BioRID II and Hybrid III ATDs over a range of low- and moderate-speed rear impact conditions. A BioRID II and a midsize male Hybrid III were tested side-by-side in a series of rear impact sled tests. To evaluate occupant response in rear impact, the ATDs were positioned into front row standard production bucket seats, restrained by 3-point safety belts, and subjected to rear impacts with delta-Vs (ΔVs) of 2.2, 3.6, 5.4, and 6.7 m/s (5, 8, 12, and 15 mph).