Examination of Crash Injury Risk as a Function of Occupant Demographics.

The objectives of this study were to provide insights on how injury risk is influenced by occupant demographics such as sex, age, and size; and to quantify differences within the context of commonly-occurring real-world crashes. The analyses were confined to either single-event collisions or collisions that were judged to be well-defined based on the absence of any significant secondary impacts. These analyses, including both logistic regression and descriptive statistics, were conducted using the Crash Investigation Sampling System for calendar years 2017 to 2021. In the case of occupant sex, the findings agree with those of many recent investigations that have attempted to quantify the circumstances in which females show elevated rates of injury relative to their male counterparts given the same level bodily insult. This study, like others, provides evidence of certain female-specific injuries. The most problematic of these are AIS 2+ and AIS 3+ upper-extremity and lower-extremity injuries. These are among the most frequently observed injuries for females, and their incidence is consistently greater than for males. Overall, the odds of females sustaining MAIS 3+ (or fatality) are 4.5% higher than the odds for males, while the odds of females sustaining MAIS 2+ (or fatality) are 33.9% higher than those for males. The analyses highlight the need to carefully control for both the vehicle occupied, and the other involved vehicle, when calculating risk ratios by occupant sex. Female driver preferences in terms of vehicle class/size differ significantly from those of males, with females favoring smaller, lighter vehicles.

The Field Relevance of NHTSA's Oblique Research Moving Deformable Barrier Tests.

A small overlap frontal crash test has been recently introduced by the Insurance Institute for Highway Safety in its frontal rating scheme. Another small overlap frontal crash test is under development by the National Highway Traffic Safety Administration (NHTSA). Whereas the IIHS test is conducted against a fixed rigid barrier, the NHTSA test is conducted with a moving deformable barrier that overlaps 35% of the vehicle being tested and the angle between the longitudinal axis of the barrier and the longitudinal axis of the test vehicle is 15 degrees. The field relevance of the IIHS test has been the subject of a paper by Prasad et al. (2014). The current study is aimed at examining the field relevance of the NHTSA test. The field relevance is indicated by the frequency of occurrence of real world crashes that are simulated by the test conditions, the proportion of serious-to-fatal real world injuries explained by the test condition, and rates of serious injury to the head, chest and other body regions in the real world crashes resembling the test condition. The database examined for real world crashes is NASS. Results of the study indicate that 1.4% of all frontal 11-to-1 o'clock crashes are simulated by the test conditions that account for 2.4% to 4.5% of all frontal serious-to-fatal (MAIS3+F) injuries. Injury rates of the head and the chest are substantially lower in far-side than in near-side frontal impacts. Crash test ATD rotational responses of the head in the tests overpredict the real world risk of serious-to-fatal brain injuries.

Children in side-impact motor vehicle crashes: seating positions and injury mechanisms.

BACKGROUND: This study aimed to describe the injury mechanisms of children involved in side-impact car crashes, particularly as these relate to seating position, and to estimate the danger of the near-side seating position. METHODS: A prospective two-center study of children involved in severe car crashes in Canada was conducted as well as a retrospective cohort study of children involved in crashes reported in the Fatality Analysis Reporting System (FARS) and the National Automotive Sampling System: Crashworthiness Data System (NASS CDS). RESULTS: Children sitting at the side the car was struck (near-side position) sustained severe head, trunk, and limb injuries. Many of these injuries were attributable to direct intrusion, but some occurred without direct damage to the occupant compartment. Center-seat and far-side occupants had severe injuries only when unrestrained. Injury severity scores were higher for children seated on the near side, and this was statistically significant (p = 0.024) The analysis of Fatality Analysis Reporting System data showed that the risk of fatality was higher for children seated in the near-side position than for those in the center-seat position. The fatality risk ratio was 2.53 (95% confidence interval [CI], 2.08-3.07) for restrained children and 1.84 (95% CI, 1.57-2.17) for unrestrained children. Analysis of the NASS-CDS data showed that for restrained children, severe injury (ISS > or = 16) was more common among those on the near side (7 per 1,000 children) than among those in the center seat (2 per 1,000) or on the far-side seat (1 per 1,000) (p < 0.001). CONCLUSIONS: Severe injuries to near-side occupants occurred in both the presence and absence of compartment intrusion. A typical pattern of head, chest, and extremity injury similar to that seen among child pedestrians was observed among near-side child occupants in side-impact crashes. The center seat was statistically safer than the near-side seat, particularly for restrained child occupants. Scene information may be useful to trauma teams for the prediction of injury type and location. Avoiding intrusion and preventing the occupant from striking the vehicle wall are both important to side-impact protection for children. Improvement of the vehicle safety cage may protect against intrusion injuries. Seating two child occupants in inboard seating positions may provide additional protection against intrusion injuries, and also may protect against nonintrusion injuries.

Ejections of young children in motor vehicle crashes.

PURPOSE: The purpose of this study was to report the incidence of ejection from the vehicle among children involved in motor vehicle crashes, and to describe a novel mode of ejection from child safety seats. METHODS: The U.S. National Automotive Sampling System General Estimates System and the Fatality Analysis Reporting System databases from 1995 through 1999 were analyzed. A prospective two-center study of children involved in severe car crashes in Canada was performed. RESULTS: Only 0.2% of 5.5 million children involved in crashes experienced ejection, but 1924 (29%) of 6570 child fatalities involved ejections. Only 2.2% of children experienced rollover crashes, but these contributed 1832 (28%) of 6570 child passenger fatalities. Among 56 crashes, 5 restrained young children were ejected, 4 in rollover crashes. Ejection of a toddler through the shoulder straps of a forward-facing child safety seat was the mechanism of ejection in three of the five cases. CONCLUSION: Ejection from the vehicle is common (29%) among fatally injured children. Shoulder straps alone (as found in T-shield or overhead shield child seats) may not prevent the ejection of toddlers from child safety seats during rollovers.

Driver and front seat passenger fatalities associated with air bag deployment. Part 1: A Canadian study.

Real world motor vehicle collision research of injuries due to deployment of "first-generation" air bags has been conducted by Transport Canada since 1993. Fifty-three fatal crashes (36 frontal impacts; 17 side collisions) involving 48 drivers and 10 right front passengers were reviewed. In the Canadian data, air bag deployment in five of nine low severity frontal crashes (delta-V (deltaV) < 25 km/h or 15 mph) was linked to five deaths, four of whom were autopsied (four adults with craniocervical (basal skull and C2 fracture with brainstem avulsion; "closed head injury"--no autopsy) or chest trauma (aortic or pulmonary artery tears); one child with atlanto-occipital dislocation). An occupant who is close ("out-of-position") to the air bag at the time of deployment is at risk for injury. In 27 high severity frontal impacts, unusual (e.g., pulmonary "blast" hemorrhage in one autopsied case) or isolated potentially survivable injuries (e.g., clinically documented ruptured right atrium; probable flail chest observed during the autopsy on a decomposed body) localized to the head, neck or chest in three possibly out-of-position drivers pointed to the deployed air bag as a source of injury. In one of 17 side collisions an out-of-position driver sustained a radiographically confirmed C1-C2 dislocation in a minimally intruded vehicle.

Driver and front seat passenger fatalities associated with air bag deployment. Part 2: A review of injury patterns and investigative issues.

Assessment of the role of air bag deployment in injury causation in a crash of any severity requires analysis of occupant, vehicle, and impact data. The potential injurious role of an air bag is independent of crash severity and is more obvious in minor collisions, particularly those involving "out-of-position" occupants. Factors such as occupant height and other constitutional and medical factors, intoxication, age, type, and proper use of other restraint systems, pre-impact braking and multiple impacts can contribute to an occupant being "out-of-position." Two injury mechanisms are described in out-of-position occupants: "punch-out" when the individual covers the air bag module before deployment and "membrane-force" when the occupant contacts a partly deployed air bag. Each mechanism is associated with injury patterns. In adults, "punch-out" can cause thoraco-abdominal trauma and "membrane-force" loading can lead to craniocervical injury. This can also occur in short-statured occupants including children subjected to both types of loading. In more severe collisions, other factors, e.g., intrusion, steering column and seatbelt loading and other occupant compartment contacts, can contribute to trauma.