NASS CDS Research Articles

The effect of seatbelt pre-tensioners and load limiters in the reduction of MAIS 2+, MAIS 3+, and fatal injuries in real-world frontal crashes

Contemporary research has pointed out that while newer cars are contributing to the decrease of AIS2+ and AIS3+ injuries in several body regions, this effect is not shown for thoracic injuries like rib or sternal fractures. The objective of this study is to assess the effectiveness of advanced seat belt systems incorporating pre-tensioners and load limiters in the prevention of fatal, AIS2+ and AIS3+ injuries overall and then focus only on the head-face-neck and thoracic areas. Data from the NASS CDS database between 2000 and 2015 was augmented with specific vehicle information taken from NHTSA’s NCAP tests to identify the characteristics of the seat belt of each vehicle involved in a collision. Multivariate logistic regressions were developed to assess the likelihood of injuries for belted front seat occupants in frontal impacts. The presence of pre-tensioners and load limiters with a low load limiter (<4.5 kN) was significantly associated with a decreased risk of fatal and AIS3+ in the whole body (OR = 0.31 (p < 0.05) and OR = 0.70 (p < 0.1)), while high load limiters were significant in the prevention of fatal injuries (OR = 0.42). These effects should be considered always in combination with the delta-v of the collision, as the interaction term between delta-v and advanced seat belt features was significant. In the crashes considered, the model predicted a higher risk of injury for women compared to men, controlling for other occupant and crash factors. Impacts with a slightly oblique component increased the risk of injury compared to pure frontal impacts. After controlling for the presence of pre-tensioners and load limiters, the vehicle model year variable was found to be insignificant in any of the regression models. This study shows that the real-world effectiveness of advanced seat belts still requires further analysis. Other effects like age or impact direction might be more influential in the injury outcome than these seat belt features.

Real-Time Regression Analysis of Streaming Clustered Data With Possible Abnormal Data Batches

This article develops an incremental learning algorithm based on quadratic inference function (QIF) to analyze streaming datasets with correlated outcomes such as longitudinal data and clustered data. We propose a renewable QIF (RenewQIF) method within a paradigm of renewable estimation and incremental inference, in which parameter estimates are recursively renewed with current data and summary statistics of historical data, but with no use of any historical subject-level raw data. We compare our renewable estimation method with both offline QIF and offline generalized estimating equations (GEE) approach that process the entire cumulative subject-level data all together, and show theoretically and numerically that our renewable procedure enjoys statistical and computational efficiency. We also propose an approach to diagnose the homogeneity assumption of regression coefficients via a sequential goodness-of-fit test as a screening procedure on occurrences of abnormal data batches. We implement the proposed methodology by expanding existing Spark’s Lambda architecture for the operation of statistical inference and data quality diagnosis. We illustrate the proposed methodology by extensive simulation studies and an analysis of streaming car crash datasets from the National Automotive Sampling System-Crashworthiness Data System (NASS CDS). Supplementary materials for this article are available online.

Analysis of Side Impact Airbag Performance in NASS CDS Ⅱ

Analysis of Side Impact Airbag Performance in NASS CDS Ⅱ

Child occupant injury risk in rear impact and frontal impact: effect of impact conditions and occupant related factors

The rear-facing seat has become a potential seating configuration for the future autonomous vehicle, therefore the potential injury risk of a rear-facing occupant merits further investigation not only for adults, but also for children. The objectives of this study were to compare the child occupant injury risk on specific body regions in frontal and rear impact, and to investigate the effect of those crash conditions and occupant related factors on the occupant injury risk. Data from the NASS–CDS and CISS were studied for crashes during 2000–2019 involving model year 2000–2020 motor vehicles, including frontal and rear–end collision. The injury risk by specific body regions were compared by descriptive statistics. Logistic regression models were developed to examine the effects of various factors on injury risk, controlling for crash type (frontal impact and rear impact), vehicle impact speed, vehicle impact location, vehicle model year, and occupant gender, age, restraint use, and seating position. After controlling for the confounding factors, the children age 3–17 had higher injury risk than infant and toddler (age 0–2) (at MAIS 2+, OR 8.71, p < 0.001). The child occupant injury risk was higher in frontal impact than in rear impact (at MAIS 2+, OR 4.96, p < 0.001), especially for children age 3–17 with the exception of the MAIS 1+ neck/spine injury risk. This study provided child injury risk references for current vehicle which may provide insight to the potential injury risk of rear-facing child occupant in future vehicle configurations.

Analysis of Side Impact Airbag Performance in NASS CDS

Analysis of Side Impact Airbag Performance in NASS CDS

Occupant injuries in light passenger vehicles—A NASS study to enable priorities for development of injury prediction capabilities of human body models

To prioritize how the development of mathematical human body models for injury prediction in crash safety analysis should be made, the most frequent injuries in the NASS CDS data from 2000 to 2015 were analyzed. The crashes were divided into seven types, from front to side. Non-minor injuries (AIS2+) were analyzed in two steps. In the first step, a grouping was made according to the AIS definition of body regions: head, face, neck, thorax, abdomen and pelvic contents, spine, upper extremities (including shoulder girdle) and lower extremities (including pelvis). In a second step, the body regions were divided in organs, parts of the spine, and parts of the extremities. The three most often injured anatomical structures of each body region were estimated for drivers and front seat passengers in each type of crash.For drivers, an injury risk greater than 2.4 % was found for the lower extremities (pelvis) and the head (concussion) in side oblique near side impacts, for the head in frontal oblique near side impacts (concussion) and for the lower extremities (ankle joint) in frontal impacts. For passengers, an injury risk greater than 2.4 % was found for the thorax (lungs) in side near side impacts, for the head (concussion) in front oblique near side impacts, and for the thorax (sternum) and the upper extremities (wrist, hand) in frontal impacts.Future development of human body models should focus on injuries to the head, thorax and the lower extremities. More specifically, it should focus on concussion in all impact directions and on rib and pelvic fractures in side near side impacts and in side oblique near side impacts.

Opportunities for crash and injury reduction: A multiharm approach for crash data analysis

ABSTRACTObjective: A multiharm approach for analyzing crash and injury data was developed for the ultimate purpose of getting a richer picture of motor vehicle crash outcomes for identifying research opportunities in crash safety.Methods: Methods were illustrated using a retrospective analysis of 69,597 occupant cases from NASS CDS from 2005 to 2015. Occupant cases were analyzed by frequency and severity of outcome: fatality, injury by Abbreviated Injury Scale (AIS), number of cases, attributable fatality, disability, and injury costs. Comparative analysis variables included precrash scenario, impact type, and injured body region.Results: Crash and injury prevention opportunities vary depending on the search parameters. For example, occupants in rear-end crash scenarios were more frequent than in any other precrash configuration, yet there were significantly more fatalities and serious injury cases in control loss, road departure, and opposite direction crashes. Fatality is most frequently associated with head and thorax injury, and disability is primarily associated with extremity injury. Costs attributed to specific body regions are more evenly distributed, dominated by injuries to the head, thorax, and extremities but with contributions from all body regions. Though AIS 3+ can be used as a single measure of harm, an analysis based on multiple measures of harm gives a much more detailed picture of the risk presented by a particular injury or set of crash conditions.Conclusions: The developed methods represent a new approach to crash data mining that is expected to be useful for the identification of research priorities and opportunities for reduction of crashes and injuries. As the pace of crash safety improvement accelerates with innovations in both active and passive safety, these techniques for combining outcome measures for insights beyond fatality and serious injury will be increasingly valuable.

Evaluating the Potential Benefits of Advanced Automatic Crash Notification.

Advanced Automatic Collision Notification (AACN) services in passenger vehicles capture crash data during collisions that could be transferred to Emergency Medical Services (EMS) providers. This study explored how EMS response times and other crash factors impacted the odds of fatality. The goal was to determine if information transmitted by AACN could help decrease mortality by allowing EMS providers to be better prepared upon arrival at the scene of a collision. The Crash Injury Research and Engineering Network (CIREN) database of the US Department of Transportation/National Highway Traffic Safety Administration (USDOT/NHTSA; Washington DC, USA) was searched for all fatal crashes between 1996 and 2012. The CIREN database also was searched for illustrative cases. The NHTSA's Fatal Analysis Reporting System (FARS) and National Automotive Sampling System Crashworthiness Data System (NASS CDS) databases were queried for all fatal crashes between 2000 and 2011 that involved a passenger vehicle. Detailed EMS time data were divided into prehospital time segments and analyzed descriptively as well as via multiple logistic regression models. The CIREN data showed that longer times from the collision to notification of EMS providers were associated with more frequent invasive interventions within the first three hours of hospital admission and more transfers from a regional hospital to a trauma center. The NASS CDS and FARS data showed that rural collisions with crash-notification times >30 minutes were more likely to be fatal than collisions with similar crash-notification times occurring in urban environments. The majority of a patient's prehospital time occurred between the arrival of EMS providers on-scene and arrival at a hospital. The need for extrication increased the on-scene time segment as well as total prehospital time. An AACN may help decrease mortality following a motor vehicle collision (MVC) by alerting EMS providers earlier and helping them discern when specialized equipment will be necessary in order to quickly extricate patients from the collision site and facilitate expeditious transfer to an appropriate hospital or trauma center. Plevin RE , Kaufman R , Fraade-Blanar L , Bulger EM . Evaluating the potential benefits of advanced automatic crash notification. Prehosp Disaster Med. 2017;32(2):156-164.

A case–control study of vehicle panel damage and thoracic injury in rollover crashes

ABSTRACTThe aim of this case–control study was to determine if there is an association between vehicle panel damage and AIS3+ thoracic injuries. NASS CDS data from 2001 to 2012 was examined for single vehicle rollover crashes with occupants receiving serious thoracic injuries (cases) and those without thoracic injuries (controls). Vehicle panel damage for cases and controls were coded and logistic regression performed to determine if there is an association between serious thoracic injury and vehicle panel damage. Furthermore, an investigation into the differences in injury sources and injury outcomes between front-seated near- and far-side occupants was performed with the data.There were two main findings from this study. First, there is an association between the rear left segment, front left upper-half door, and front right upper-half door damage and serious thoracic injury. Second, the sources of thoracic injuries and the thoracic viscera injured are different for near-side and far-side occupants.

Similarity scoring methodology for comparing real-world cases to crash test standards

A National Automotive Sampling System–Crashworthiness Data System (NASS–CDS) based Similarity Scoring Methodology (SSM) is presented for the quantitative comparison of real-world crashes to crash tests. Using NASS–CDS 2000–2008, five categorical and five continuous crash, vehicle and occupant parameters were utilised for frontal and side impacts. Mahalanobis metric results revealed that 1% of frontal and 23% of side NASS–CDS cases scored received similarity scores of <0.14 demonstrating greater similarity to standard crash tests. These included 20,334 frontal and 442,511 side impact case occupants (weighted). On average, the best scores occurred for NASS–CDS cases compared to FMVSS 214 side crash tests. The majority of real-world crashes had lower delta-Vs and maximum crush than associated crash tests. The results will aid in the study of occupant safety and vehicle crashworthiness by helping researchers identify population groups to study real-world injuries versus the injury risk predicted by anthropomorphic test devices.

Obesity and non-fatal motor vehicle crash injuries: sex difference effects

BackgroundObesity and motor vehicle crash (MVC) injuries are two parallel epidemics in the United States. An important unanswered question is if there are sex differences in the associations between the presence of obesity and non-fatal MVC injuries.ObjectivesTo further understand the association between obesity and non-fatal motor vehicle crash injuries, particularly the sex differences in these relations.MethodsWe examined this question by analyzing data from the 2003 to 2007 National Automotive Sampling System Crashworthiness Data System (NASS CDS). A total of 10, 962 drivers who were aged 18 years or older and who survived frontal collision crashes were eligible for study.ResultsMale drivers experienced a lower rate of overall non-fatal MVC injuries than did female drivers (38.1% vs. 52.2%) but a higher rate of severe injuries (0.7% vs. 0.2%). After adjusting for change in velocity (ΔV) during the crashes, obese male drivers showed a much higher risk [logistic coefficients of BMI for moderate, serious, and severe injury are 0.0766, 0.1470, and 0.1792, respectively; all p<0.05] of non-fatal injuries than did non-obese male drivers and these risks increased with injury severity. Non-fatal injury risks were not found to be increased in obese female drivers. The association between obesity and risk of non-fatal injury was much stronger for male drivers than for female drivers.ConclusionThe higher risk of non-fatal MVC injuries in obese male drivers might result from their different body shape and fat distribution compared with obese female drivers. Our findings should be considered for obesity reduction, traffic safety evaluation and vehicle design for obese male drivers and provide testable hypotheses for future studies.

Motor vehicle mismatch: a national perspective

ObjectiveTo determine the RR of the severe injury associated with light truck vehicle (LTV) versus passenger vehicle (PV) mismatch following motor vehicle collisions across the USA.MethodsThis was a retrospective cohort...

Mortality and injury patterns associated with roof crush in rollover crashes

Background In the United States, a significant number of spine injuries, traumatic brain injuries (TBI), and deaths result from motor vehicle rollover crashes each year though they make up a small percentage of total crashes. We sought to explore the relationship between these injuries and the degree of roof crush. Methods We searched the NASS CDS database for belted, adult (≥16), non-middle seat passengers involved in rollover crashes from 1993 to 2006. We also searched the CIREN database for illustrative cases. Logistic regression was used to evaluate the relationship between different levels of roof crush and mortality, severe injury (AIS ≥3) to the spine, spinal cord, and head injury. Results The risk of mortality, TBI, and spine injury all increased as the degree of roof crush increased. For mortality increased risk occurred at >15 cm [15–30 cm: OR 2.089 (95% CI: 1.461–2.987); >30 cm: OR 6.301 (95% CI: 4.369–9.087)]. For TBI, increased risk was seen above 15 cm crush [15–30 cm: OR 1.52 (95% CI: 1.045–2.21); >30 cm: OR 3.672 (95% CI: 2.456–5.490)]. For spine injury increased risk was seen above 8 cm crush [8–15 cm: OR 1.968 (95% CI 1.273–3.043); 15–30 cm: OR 2.530 (95% CI 1.634–3.917); ≥30 cm OR 2.682 (95% CI 1.474, 4.877). Results were similar across the different statistical models. Conclusion There is an association between the degree of roof crush and mortality, spine injury, and head injury in rollover crashes.

Differences in the Effectiveness of Frontal Air Bags by Body Size Among Adults Involved in Motor Vehicle Crashes

Objective. There is concern that small stature occupants (particularly women) involved in motor vehicle crashes (MVCs) may be at risk of injury or death from frontal air bags, though evidence to substantiate this concern is lacking. We sought to assess how occupant body size (measured through height and weight) affects air bag effectiveness in mitigating the risk of serious injury, after adjusting for important crash factors. Methods. This was a retrospective cohort study using a national population-based cohort of adult front-seat occupants involved in MVCs as included in the National Automotive Sampling System Crashworthiness Data System database (NASS CDS) from 1995 to 2006. Drivers and front-seat passengers 15 years and older involved in MVCs involving passenger vehicles and light trucks were included in the analysis. The primary outcome was serious injury, defined as an Abbreviated Injury Scale (AIS) score ≥3 in any body region. Multivariable logistic regression models were used to test interaction terms (effect modification) between air bags, body size, and injury. The predicted probability of injury across body sizes was plotted to further illustrate potential differences. Results. Sixty-nine thousand three hundred eighty-seven adult front-seat occupants during the 12-year period were included in the analysis, of which 9333 (2.3%) were seriously injured. There was no evidence that height or weight modified air bag effectiveness among all crashes (p > .40). In primary frontal collisions, there was some evidence for effect modification by weight (p = .04) but not by height (p = .59). When assessed using air bag deployment, height was a strong effect modifier (p = .0078), but not weight (p = .43). Predicted probability figures confirmed that occupant height modifies the effect of air bag deployment, but there was no similar visual evidence for body weight. Conclusions. In this sample, we found no consistent evidence that body size modifies the overall effectiveness of frontal air bags. However, among crashes involving air bag deployment, the effect of deployment on injury differs by occupant height, with a relative increase in the odds of serious injury among smaller occupants. In such crashes, the probability of injury with (versus without) deployment began to increase with occupant heights less than 155 cm (5′), reaching a level of statistical difference below 138 cm (4′ 6″).

Seat position and the risk of serious thoracoabdominal injury in lateral motor vehicle crashes

Context: Previous studies have suggested that motor vehicle occupants seated on the near-side of a lateral impact have a higher proportion of thoracoabdominal injuries. However, due to limitations in previous studies, the true association between seat position, side of lateral impact, and thoracoabdominal injury is unclear. Objective: To assess the relationship between seat position (i.e., near-side, middle-seat, and far-side, regardless of row), side of lateral motor vehicle crash (MVC), and serious thoracoabdominal injury after adjusting for important crash factors. Design: National population-based cohort of adult subjects involved in MVCs and included in the National Automotive Sampling System Crashworthiness Data System database (NASS CDS) from 1995 to 2003. Patients: Occupants aged ≥16 years involved in MVCs where the highest external deformation of the vehicle was located on the right or left side (i.e., lateral). Main outcome measure: Serious thoracic or abdominal injury, defined as an Abbreviated Injury Scale (AIS) ≥3 in the thoracic or abdominal body region. Results: Fifteen thousand, one hundred and sixty persons involved in primary lateral MVCs were represented in the NASS CDS database during the 9-year period. There were 1867 (2%) persons with serious thoracic injuries and 507 persons (0.5%) with serious abdominal injuries. In multivariable logistic regression models that adjusted for important crash factors and the NASS CDS sampling design, seat position was a strong effect modifier of the association between side of lateral impact and serious thoracic ( p < 0.0001) and abdominal ( p = 0.0009) injury, with the risk of serious thoracic and abdominal injury highest for occupants seated on the near-side of the crash. The mean probability of injury was higher for near-side and middle-seat occupants compared to far-side occupants, and the probability of thoracic injury was approximately four times higher than that of abdominal injury for all seat positions. Conclusions: There is a strong, synergistic relationship between seat position and side of lateral MVC in assessing risk of serious thoracic and abdominal injury among adult occupants. The probability of serious thoracoabdominal injury increases with increasing proximity of seat position to side of the crash and the risk of thoracic injury is higher than abdominal injury for all seat positions.

Factors affecting pelvic and thoracic forces in near-side impact crashes: a study of US-NCAP, NASS, and CIREN data

The goal of this study was to identify variables related to vehicle design which are associated with pelvic and thoracic accelerations as measured by the driver's (near side) crash dummy during new car assessment program (NCAP) testing of motor vehicles. Vehicle specific parameters were analyzed using NCAP side impact test results. Data from national automotive sampling system, crashworthiness data system (NASS–CDS) and crash injury research and engineering network (CIREN) (both National Highway Traffic Safety Administration (NHTSA) injury databases) were assessed to confirm NCAP test observations. In addition, door armrest stiffness measurements were performed using a mechanical tester on a sample of 40 vehicles. NCAP data showed that of 10 variables tested using multiple linear regression, vehicle weight and door crush correlated with pelvic acceleration of the driver's crash dummy (overall, r 2 = 0.58, p = 0.002, n = 165). For thoracic trauma index (TTI) vehicle weight and peak door velocity correlated, significantly (overall, r 2 = 0.41, p = 0.03, n = 165). Mean TTI was 63.7 g with no side airbag ( n = 108) and 55.6 g with a thoracic side airbag ( n = 54), p = 0.01. The mean vehicle weight and door crush between airbag and no airbag groups were not significantly different. NASS–CDS data demonstrated a direct relationship between increased door crush and increased abbreviated injury score (AIS). CIREN data showed that occupants who sustained pelvic injuries had a median AIS of 3 with 24.9 cm of door crush, with abdominal injuries, a median AIS of 3 and 30 cm of crush, and with thoracic injuries, a median AIS of 4 and 34 cm of door crush. In addition, the frequency of bilateral pelvic injuries was significantly higher for subjects in CIREN crashes who were in a vehicle with a center console, but only if door intrusion was greater than 15 cm. This information may be useful in design of vehicles with greater protection in side impact crashes.

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

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. 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). 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). 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.