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The risk of sustaining injury in side collisions is correlated to collision severity as well as other factors such as restraint usage and occupant position relative to the impact. The most recent National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) data available (1997 to 2007) were analyzed to identify accidents involving passenger vehicles that have experienced an impact with a principal direction of force (PDOF) either between 8:00 and 10:00 or between 2:00 and 4:00, indicating a side 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, restraint system use, and occupant position relative to the impact.

Seatback strength and injury potential in moderate to high-speed rear-end collisions were investigated in a series of 12 HYGE sled tests. The test methodology included the use of instrumented Hybrid-III anthropomorphic test devices (ATDs). Four tests employed a 95th percentile male ATD ballasted to a total weight of 300 lbs and subjected to approximate 15 mph Delta-V impacts. The remaining tests employed an unmodified 50th percentile male ATD with impacts of approximately 25 mph Delta-V, and three ATD positions, including two "out of position" postures corresponding to leaning forward ("forward" position), and leaning forward and inboard ("radio" position). Seats from three different vehicles were tested, representing a range of strength values. Upper neck values for N were less than 1.0 in all cases. Lower neck N values sometimes exceeded 1.0 with the 50th percentile male ATD out of position, and these values did not trend with seatback strength.

The risk of sustaining injury in frontal collisions is correlated to collision severity as well as other factors such as restraint usage and airbag deployment. Eleven years (1997 to 2007) of National Automotive Sampling System (NASS) data from the Crashworthiness Data System (CDS) were analyzed to identify accidents involving passenger vehicles that have experienced an impact with a principal direction of force (PDOF) between 11:00 and 1:00, indicating a frontal 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 factors such as delta-V, restraint system use, and airbag deployment. Each body region (head, face, spine, thorax, abdomen, upper extremity, and lower extremity) was considered separately.

Police accident reports (PARs) of motor vehicle collisions typically include information regarding occupant restraint use. It has been suggested that PARs overestimate restraint use. Previous studies comparing PAR restraint usage with that determined during a NASS/CDS in-depth investigation found agreement in approximately 90% of cases. The accuracy of PAR-reported restraint usage for outboard vehicle occupants was compared to that determined by NASS/CDS investigators as a function of injury severity and crash type. Restrained occupants were more likely to be identified correctly in the PAR, and unrestrained occupants were more likely to be accurately identified as injury severity increased. Differences in the accuracy of PAR-reported restraint usage rates for different crash types were small.

This study integrates data from multiple sources to obtain a more complete understanding of inertially-induced pediatric cervical spine injury risk and the role of impact severity and restraint type. Data from previously conducted frontal crash and sled tests using a variety of anthropomorphic test devices (ATDs) in various restraint configurations were compiled and compared to injury assessment reference values (IARVs). The data show that neck loads in frontal collisions increase with increasing delta-V. At high delta-Vs, the neck loads correspond to a relatively high risk of neck injury regardless of restraint configuration. Pediatric inertial cervical spine injury risk in frontal collisions is governed primarily by the energy involved in the collision.

Vehicle occupants undergo upward and outward excursion during the airborne phase of vehicle rollover due to the inertial effects coming from the vehicle's rotation. When this excursion is sufficient to permit contact between the occupant's head and the vehicle's interior roof panel, the neck may experience compressive loading. This compressive loading, generated during the airborne phase and prior to vehicle-to-ground impact, could render the occupant more susceptible to compressive neck injury during subsequent vehicle-to-ground impacts. In the present study, computational simulations were used to evaluate the effect of steady-state roll rate on compressive preloading in the cervical spine. The results show an increasing relationship between roll rate and compressive preloading when the head contacts the roof panel and becomes constrained.

During a rollover accident the position of an occupant within a vehicle at the time of vehicle-to-ground contact affects the occupant's injury potential and injury mechanisms. During rollovers, the accelerations developed during the airborne phases cause an occupant to move away from the vehicle's center of mass towards the perimeter of the vehicle. The occupant is already in contact with vehicle structures during upper vehicle structure-to-ground impacts. The location and extent of the occupant-to-vehicle contacts and the times and locations at which the contacts occur depend upon a variety of factors including occupant size, initial position in the vehicle, restraint status, vehicle geometry, and rollover accident parameters. Onboard and offboard video of existing dolly rollover studies, specifically the “Malibu” studies, were examined to quantify the motion of the occupants' heads and determine the timing and locations of head contacts to the vehicle perimeter.

There is a paucity of data regarding the potential for pediatric cervical spine injury as a result of acceleration of the head with no direct impact during automotive crashes. Sled tests were conducted using a 3-year-old anthropomorphic test device (ATD) to investigate the effect of restraint type and crash severity on the risk of pediatric inertial neck injury. At higher crash severities, the ATD restrained by only the vehicle three-point restraints sustained higher peak neck tension, peak neck extension and flexion moments, neck injury criterion (Nij) values, peak head accelerations, and HIC values compared to using a forward-facing child restraint system (CRS). The injury assessment reference values (IARVs) for peak tension and Nij were exceeded in all 48 and 64 kph delta-V tests using any restraint type.

Vehicle aspect ratio has been reported as a significant factor influencing the likelihood of fatality or severe injury/fatality during single-vehicle rollover crashes. To investigate this, dynamic simulations of friction-induced rollover accidents were performed using different roof heights, but otherwise identical vehicle parameters and initial conditions. Higher aspect ratios tended to cause the leading side roof to impact first, with significant impact force. The roof impact forces during the first roll of higher-roofed vehicles were primarily laterally directed with respect to the vehicle. Impact locations during subsequent rolls were less predictable. Lower aspect ratios produced higher impact forces on the trailing side roof that were more vertically oriented with respect to the vehicle. The vertically oriented forces potentially create greater risk for severe neck or head injuries.

Anthropomorphic test dummies (ATDs) have been validated for the analysis of various types of automobile collisions through pendulum, impact, and sled testing. However, analysis of the fidelity of ATDs in rollover collisions has focused primarily on the behavior of the ATD head and neck in axial compression. Only limited work has been performed to evaluate the behavior of different surrogate models for the analysis of occupant motion during rollover. Recently, Moffatt et al. examined head excursions for near- and far-side occupants using a laboratory-based rollover fixture, which rotated the vehicle about a fixed, longitudinal axis. The responses of both Hybrid III ATD and human volunteers were measured. These experimental datasets were used in the present study to evaluate MADYMO ATD and human facet computational models of occupant motion during the airborne phase of rollover.