National Automotive Sampling System Database Research Articles

Analysis of Delta Velocity and PDOF by Means of Collision Partner and Structural Involvement in Real-Life Crash Pulses With Modern Passenger Cars

Objective: In the widely used National Automotive Sampling System (NASS)-Crashworthiness Data System (CDS) database, summary metrics that describe crashes are available. Crash angle or principal direction of force (PDOF) is estimated by the crash examiner and velocity changes (ΔV) in the x- and y-directions are calculated by the WinSMASH computer program using PDOF and results from rigid barrier crash testing combined with deformations of the crashed car. In recent years, results from event data recorders (EDRs) have been added to the database. The aim of this study is to compare both PDOF and ΔV between EDR measurements and WinSMASH calculations. Methods: NASS-CDS inclusion criteria were model-year 2000 through 2010 automobiles, frontal crashes with ΔV higher than 16 km/h, and the pulse entirely recorded in the EDR module. This resulted in 649 cases. The subject vehicles were further examined and characterized with regard to frontal structure engagement (large or small overlap) as well as collision properties of the partner (impact location; front, side, or back) or object. The EDR crash angle was calculated as the angle between the lateral and longitudinal ΔV at the time of peak longitudinal ΔV. This angle was compared to the NASS-CDS investigator's estimated PDOF with regard to structural engagement and the collision partner or object. Multiple linear regression was used to establish adjustment factors on ΔV and crash angle between the results calculated based on EDR recorded data and that estimated in NASS-CDS. Results: According to this study, simulation in the newest WinSMASH version (2008) underestimates EDR ΔV by 11 percent for large overlap crashes and 17 percent for small overlap impacts. The older WinSMASH version, used prior to 2008, underestimated each one of these two groups by an additional 7 percentage points. Another significant variable to enhance the prediction was whether the crash examiner had reported the WinSMASH estimated ΔV as low or high. In this study, none of the collision partner groups was significantly different compared to front-to-front impacts. However, with a larger data set a couple of configurations may very well be significantly different. In this study, the crash angle denoted by PDOF in the NASS database underestimates the crash angle calculated from recent EDR modules by 35 percent. Conclusion: On average the ΔV and crash angle are underestimated in NASS-CDS when analyzing the data based on collision partner/object and structural engagement. The largest difference is found in small overlap crashes and the least difference in collision scenarios similar to barrier tests. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.

Injury and Side Impact Air Bag Deployment in Near and Far Sided Motor Vehicle Crashes, United States, 2000–2005

Side impact crashes, the most lethal type, account for 26% of all motor vehicle crashes in the United States. The purpose of this study is to delineate side impact airbag (SIAB) deployment rates, injury rates, and analyze crash factors associated with SIAB deployment and occupant injury. All passenger vehicles equipped with SIABs that were involved in a side impact crash were identified from the National Automotive Sampling System database. Crashes with multiple impacts, ejections, unbelted drivers or rollovers were excluded from the study. The outcome variables of interest were SIAB deployment and driver injury. SIAB deployment was compared in similar crashes to analyze the impact on driver's injury severity score. Other crash factors were also examined to analyze what role they play in SIAB deployment rates and injury rates, such as plane of contact, striking object and Delta-V. The data set for this study contained 247 drivers in near and far side crashes in vehicles with installed SIABs. Overall SIAB deployment was 43% in side impact crashes. A significant factor associated with both the SIAB deployment rate and the driver's injury rate was increased Delta-V. SIABs do not deploy consistently in crashes with a high Delta-V or with a lateral primary direction of force and a front plane of contact. In these two scenarios, further research is warranted on SIAB deployments. With SIAB deployment, it appears drivers are able to sustain a higher Delta-V impact without serious injury.

Severe upper extremity injuries in frontal automobile crashes: the effects of depowered airbags

Background The purpose of this study was to determine the effects of depowered frontal airbags on the incidence of severe upper extremity injuries. Methods The National Automotive Sampling System database files from 1993 to 2000 were examined in a study that included 2,413,347 occupants who were exposed to an airbag deployment in the United States. Results Occupants exposed to a depowered airbag deployment were significantly more likely to sustain a severe upper extremity injury (3.9%) than those occupants exposed to a full-powered airbag deployment (2.5%) ( P = .01). Full-powered systems resulted in an injury distribution of 89.2% fractures and 7.9% dislocations compared with depowered systems with 55.3% fractures and 44.3% dislocations. Conclusions Although depowered airbags were designed to reduce the risk of injuries, they appear to have increased the overall incidence of severe upper extremity injuries through a shift from long bone fractures to joint dislocations.

Odontoid fracture in motor vehicle environments

The National Automotive Sampling System (NASS) and Crash Injury Research and Engineering Network (CIREN) databases were used in an analysis of odontoid fracture in motor vehicle crashes. NASS data were evaluated for the years 1996–2002, and CIREN from 1996 to 2003. Out of 58 fractures, 38 were identified in the NASS and 20 in the CIREN databases. There were 3108 weighted cases in the NASS database. Frontal impacts (11:00 to 1:00 h) were most commonly associated with the injury in both databases. Although male and female occupants sustained the injury, females were shorter in stature, older in age, lighter in weight, and crashes were less severe (lower change in velocity) when female occupants were involved in trauma. In both databases, pure odontoid fracture and facet/lamina fracture accounted for approximately one-third of the cases, and a majority of impacts were associated with changes in velocity less than 56 km/h. Although vehicle model years ranged from 1976 to 2002, recent model years were more frequently associated with CIREN data. In the CIREN database, type II odontoid fracture was the most common, but no particular mechanism of injury dominated; such information was not available in the NASS database. To ameliorate odontoid fracture, focus should be on frontal impacts. Because different types of odontoid fracture are not included in the current Abbreviated Injury Scale, appropriate coding schemes should be developed to classify this injury. The CIREN database is unique because it provides important clinical information, i.e., fracture type, and the associated mechanism of injury. The mechanism component in any epidemiologically based injury analyses is valuable to advance improvements in vehicle crashworthiness.

The Effects of Depowered Airbags on Skin Injuries in Frontal Automobile Crashes

The purpose of this study was to determine the effects of depowered frontal airbags on the incidence of skin injuries. The National Automotive Sampling System database files from 1993 to 2000 were examined in a study including 2,246,524 occupants exposed to airbag deployment in the United States. There was no significant difference between full-powered and depowered airbags, with 60.2 percent of those exposed to a full-powered deployment sustaining a skin injury versus 59.5 percent of occupants exposed to a depowered airbag (p = 0.19). Whether occupants were exposed to a full-powered airbag (1,936,485 occupants) or a depowered airbay (310,039 occupants), the majority of skin injuries were to the upper extremity and the face. Regardless of airbag power, the overwhelming majority of the skin injuries were minor (99.8 percent). There was not a significantly greater risk of injury from any source for occupants exposed to a depowered airbag or a full-powered airbag (p = 0.87). The data suggest that the implementation of depowered airbags did not affect the number, seriousness, location, or source of skin injuries.

The effects of depowered airbags on eye injuries in frontal automobile crashes

The purpose of this study was to investigate eye injuries resulting from frontal automobile crashes and to determine the effects of depowered airbags. The National Automotive Sampling System database files from 1993 to 2000 were examined in a 3-part investigation of 22 236 individual crashes. Of the 2 103 308 occupants exposed to a full powered deployment, 3.7% sustained an eye injury compared to 1.7% of the 310 039 occupants exposed to a depowered airbag deployment. Occupants were at a significantly higher risk to sustain an airbag-induced eye injury when exposed to a full powered airbag compared with occupants exposed to a depowered airbag deployment ( P = .04). Approximately, 90% of the eye injuries in full powered airbag deployments were caused by the airbag, compared to only 35% of the depowered airbag eye injuries.

Traumatic brain injury and automotive design: making motor vehicles safer.

Traumatic brain injury (TBI) remains a major public health problem in the United States. Identifying and modifying vehicle designs associated with TBI will have a significant impact on the frequency and severity of TBI in motor vehicle crashes (MVCs). Our objective, therefore, was to identify interior vehicle contact points associated with severe TBI (head Abbreviated Injury Scale score > 3) among drivers and determine the extent to which modifications of these contact points impact the likelihood of severe TBI. We analyzed drivers in MVCs from the 1993 to 2001 National Automotive Sampling System database. The odds of severe TBI with respect to various vehicle contact points were estimated using multivariate logistic regression. Using computer simulation software, the magnitude of driver head deceleration was modeled while manipulating vehicle design features. The potential impact of this design modification on the frequency and hospital charges of TBI cases was estimated. There were 18,313 drivers involved who were victims of TBI, equating to a national sample size of 3,275,472 cases. The most frequent contact point associated with severe TBI was the roof rail (odds ratio, 2.0; 95% confidence interval, 1.2-3.3). Increasing roof rail padding thickness to 5.0 cm reduced the peak acceleration from 700 g to 218 g, which would potentially reduce the attributable number of severe TBI cases per year from 2,730 to 210, thereby reducing annual acute care charges from $136.5 million to $10.5 million US dollars. Contact with the roof rail significantly increases the likelihood of TBI in MVCs. Minor increases in padding at these points may reduce the frequency of severe TBI, which would have a substantial effect on health care costs.

The effects of airbags on orbital fracture patterns in frontal automobile crashes.

To investigate orbital fractures that occurred in frontal automobile crashes and to determine the effects of frontal airbags on injury incidence and severity. The National Automotive Sampling System database files from 1993 to 2000 were examined. Frontal crashes were selected that included drivers and front-seat passengers only and excluded ejected occupants and rollover crashes. Orbital fractures could be closed, open, displaced, or any combination of these and were identified by using the Abbreviated Injury Scale codes. The analysis included 12,429,580 front-seat occupants from 25,464 cases. Of all occupants who were exposed to an airbag deployment, 0.09% sustained an orbital fracture. In contrast, occupants who were not exposed to an airbag deployment were more than twice as likely to sustain an orbital fracture (0.22%). In addition to reduction in incidence, airbags were also shown to decrease the severity of orbital fractures that occupants sustained. Occupants exposed to airbag deployment mostly sustained closed, less severe fractures (61.9%), whereas occupants not exposed to airbag deployment sustained the majority as more severe, open, displaced, or comminuted fractures (61.3%). This article presents the most comprehensive study of orbital fractures in automobile crashes to date. It is shown that both the incidence and the overall severity of orbital fractures decreases considerably with exposure to airbag deployment. This is accomplished because the airbag minimizes occupant contact with the windshield and steering wheel, which are the two leading sources of orbital fractures for occupants not exposed to airbag deployment.

The effects of airbag deployment on severe upper extremity injuries in frontal automobile crashes

The purpose of this study was to investigate severe upper extremity injuries resulting from frontal automobile crashes and to determine the effects of frontal airbags. The National Automotive Sampling System database files from 1993 to 2000 were examined in a study that included 25,464 individual cases that occurred in the United States. An analysis of the cases indicated that occupants exposed to an airbag deployment were statistically more likely to sustain a severe upper extremity injury (2.7%) than those occupants not exposed to an airbag deployment (1.6%) (P = .01). In particular, 0.7% of occupants exposed to an airbag deployment sustained a severe upper extremity injury specifically from the airbag. In addition, when in crashes with an airbag deployment, older occupants were at a higher risk for severe upper extremity injury, as well as occupants in crashes with higher changes in velocity. (Am J Emerg Med 2003;21:100-105. Copyright 2003, Elsevier Science (USA). All rights reserved.)

The effect of frontal air bags on eye injury patterns in automobile crashes.

To investigate eye injuries resulting from frontal automobile crashes and to determine the effects of frontal air bags. The National Automotive Sampling System database files from January 1, 1993, through December 31, 1999, were examined in a 3-part study that included an investigation of 22 236 individual crashes that occurred in the United States. A new 4-level eye injury severity scale that quantifies injuries based on recovery time, need for surgery, and possible loss of sight was developed. Of all occupants who were exposed to an air bag deployment, 3% sustained an eye injury. In contrast, 2% of occupants not exposed to an air bag deployment sustained an eye injury. A closer examination of the type of eye injuries showed that there was a statistically significant increase in the risk of corneal abrasions for occupants who were exposed to an air bag compared with those who were not (P =.03). Of occupants exposed to an air bag deployment, 0.5% sustained a corneal abrasion compared with 0.04% of occupants who were not exposed to an air bag. Using the new injury levels, it was shown that although occupants exposed to an air bag deployment had a higher risk of sustaining minor eye injuries, the air bag appears to have provided a beneficial exchange by reducing the number of severe eye injuries.

Abdominal Injury Patterns in Motor Vehicle Accidents: A Survey of the NASS Database from 1993 to 1997

The purpose of this study was to determine patterns of abdominal injuries using the publicly available National Automotive Sampling System (NASS) database. Data from the NASS database for the years between 1993 and 1997 were extracted in order to gain an enhanced understanding of abdominal injury patterns resulting from vehicular collisions. The liver was most frequently injured due to contact with components in the front of the passenger compartment, such as the steering assembly and the instrument panel. Injuries to the spleen frequently resulted from contact with components on the left side of the passenger compartment. When considering only contact with components on the sides of the passenger compartment, the liver was injured more frequently due to contact with components on the right side of the passenger compartment while contact with components on the left side of the passenger compartment were more likely to result in injuries of the spleen. A more in-depth survey of the NASS database will be needed to determine if the asymmetrical features of human anatomy must be considered in the design of crash test dummies and mathematical models used in the evaluation of abdominal impact protection in automotive accidents.

Use of out-of-hospital variables to predict severity of injury in pediatric patients involved in motor vehicle crashes

Study Objective: We sought to create a clinical decision rule, on the basis of variables available to out-of-hospital personnel, that could be used to accurately predict severe injury in pediatric patients involved in motor vehicle crashes as occupants. Methods: We analyzed the National Automotive Sampling System database, a national probability sample, using pediatric patients up to 15 years old (occupants only) involved in motor vehicle crashes from January 1993 to December 1999. The National Automotive Sampling System database includes patients from regions throughout the country, weighted to represent a nationwide sample. Twelve out-of-hospital variables were used in classification and regression tree analysis to create a decision rule separating children with severe injuries (Injury Severity Score [ISS] ≥16) from those with minor injuries (ISS<16). Misclassification costs and complexity parameters were selected to yield a decision tree with appropriate sensitivity and specificity for the identification of severely injured patients, while also being simple and practical for out-of-hospital use. Probability weights were used throughout the analysis to account for the sampling design and sampling weights. Results: Using a sample size of 8,392 children, we constructed a decision rule using 3 out-of-hospital variables (Glasgow Coma Scale score, passenger space intrusion ≥6 in [≥15 cm], and restraint use) to predict those patients with an ISS of 16 or more. Internal cross-validation was used to determine the sensitivity and specificity, yielding values of 92% and 73%, respectively, for the prediction of patients with an ISS of 16 or more. Conclusion: Out-of-hospital variables available to field personnel could be used to effectively triage pediatric motor vehicle crash patients using the decision rule developed here. Prospective trials would be needed to test this decision rule in actual use. [Newgard CD, Lewis RJ, Jolly BT. Use of out-of-hospital variables to predict severity of injury in pediatric patients involved in motor vehicle crashes. Ann Emerg Med. May 2002;39:481-491.]