Unbelted Occupants Research Articles

Injury comparisons between paired drivers and front-seat passengers in frontal collisions using publicly available crash and injury data.

Forensic engineers and crash safety researchers sometimes use the injuries of a seatbelted occupant to infer the injury risk of an unbelted occupant in the same crash, had they instead been wearing a seatbelt. It is unclear, however, whether this inference is valid or how often two occupants in the same collision have similar injuries. Here, we sought to compare the injury outcomes between drivers and front-seat passengers in frontal collisions using real-world collision data. We compared the injury severity, quantified using the Abbreviated Injury Scale (AIS), of 22 injury categories between front-seat occupants with matching seatbelt use and airbag deployment in single-event frontal collisions recorded in the publicly available National Automotive Sampling System, Crashworthiness Data System (years 1993-2015) database to assess whether they had similar severity injuries. We analyzed the four combinations of seatbelt use and airbag deployment and all seatbelt/airbag conditions combined. In only 3 of 88 combinations of injuries and seatbelt/airbag conditions did more than 50% of occupant pairs have the same AIS score, although the related confidence intervals showed these proportions were not significantly greater than 50%. In contrast, we found 19 combinations of injuries and seatbelt/airbag conditions where one occupant was consistently injured more severely than the other. Our findings show that injury outcome is not similar for both front-seat occupants in the same frontal collision with similar seatbelt and airbag conditions; however, one may be able to predict that one occupant would be more severely injured than their fellow occupant.

Adult occupant injury risk in rear impact and frontal impact: Effect of impact conditions and occupant-related factors

Objectives The objectives of this study were to compare the adult 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 injury risk. Method Data from the NASS-CDS and Crash Investigation Sampling System were studied for crashes during 2000 to 2019 involving model year 2000 to 2020 motor vehicles, including frontal collisions and rear-end collisions. The injury risk by specific body regions were compared by descriptive statistics, and logistic regression models were developed to examine the effects of various factors on injury risk by specific body regions, controlling for crash type (frontal impact and rear impact), vehicle impact speed, vehicle impact location, vehicle model year, and occupant gender, age, belt use, and seating position. Results After controlling for the confounding factors, the occupants in frontal impact had higher overall injury risk than in rear impact (at Maximum Abbreviated Injury Scale [MAIS] 3+; odds ratio [OR] = 6.23; 95% confidence interval [CI] [6.06–6.40]), except for lower neck/spine injury risk at MAIS 1+ (OR = 0.47; 95% CI [0.46–0.47]). The impact speed (at MAIS 3+; OR = 1.10; 95% CI [1.10–1.10]) and aging (at MAIS 3+; OR = 1.05; 95% CI [1.05–1.05]) increase overall injury risk, and the unbelted occupants had higher overall injury risk than belted occupants not only in frontal impact (at MAIS 3+; OR = 4.04; 95% CI [3.98–4.10]), but also in rear impact (at MAIS 3+; OR = 28.4; 95% CI [26.4–30.5]). Females had higher overall injury risk than males in frontal impact (at MAIS 3+; OR = 2.01; 95% CI [1.99–2.04]) but not in rear impact (at MAIS 3+; OR = 0.77; 95% CI [0.73–0.81]). Conclusions Occupants in rear impact had lower injury risk than in frontal impact at MAIS 1+ to MAIS 3+, except for neck/spine at MAIS 1+. The belt restraint was effective not only in frontal impact but also in rear impact. This study provided injury risk references for current vehicles that may provide insight to the potential injury risk of rear-facing occupants in future vehicle configurations.

Effects of sedan wheelbase size on left rear-seat occupant injury risk in small offset crashes

The objective of this study was to investigate the effect of sedan wheelbase size on the kinematics and injury severity of left rear-seat occupants by using the finite element (FE) modeling method. A total of 270 cases with detailed accidental information records were analyzed to define the influence laws of wheelbase size and impact speed on the injury of left rear-seat occupants. First, the THUMS (Ver. 4.0.2) FE model was used to reconstruct two small offset collisions with different wheelbases size and unbelted left rear-seat occupants, and the effectiveness of the accident model was verified. Then, seatbelts were added to the left rear-seat occupant models. Finally, LS-DYNA software was used to study the correlation among head and chest injury and five sedan wheelbases sizes (2300, 2450, 2600, 2750, and 2905 mm) at three impact velocities (54, 64, and 74 km/h). The results showed that the occupants’ chest injuries showed an upward trend at the impact velocity of 64 and 74 km/h when the wheelbases sizes was reduced to 2300 mm. This research illustrated that at higher impact velocities, excessively small wheelbases might increase the chest injury severity of left rear-seat occupants.

Influence of non-standard seating postures on safety of motorcoach passengers in frontal collisions: A numerical study

With increasing public concern about the safety of motorcoach passengers, new regulations have been established for large passenger vehicles worldwide. In contrast to regulation testing, the real-world environment features several uncertainties that can potentially increase the injury risk for occupants. This paper is aimed at investigating the effect of the non-standard occupant seating posture, stature and low seatbelt usage rate on the safety of motorcoach passengers in frontal collisions. The study is performed numerically, using the validated finite element model of a sled test. The posture of the two unbelted occupants, 5th and 95th percentile ATDs, is varied stochastically according to the results of a volunteer study available in the literature. Compared to the reference posture used in the regulation testing, a maximum variation of +104% is observed for the Head Injury Criterion (HIC) and +58% for the femur forces of the 95th percentile ATD. The HIC and femur forces for the 5th percentile ATD and neck injury criteria for both ATDs demonstrate a difference of about 20% from the standard posture. No direct correlation is observed between posture parameters and the probability of an injury. Overall, the results of the study provide an estimate of the dispersion in the injury criteria values introduced by posture variations and highlight the importance of accounting for the real-world uncertainties during design and testing of vehicle structures.

Field data analysis of recreational off-highway vehicle crashes

Objective: Recreational off-highway vehicle (ROHV) crashes are of concern because sales of these vehicles have been growing rapidly and because newer vehicles tend to have significantly greater performance than older models. We evaluated the available data to understand trends in ROHV crashes and the factors that contributed to serious injury.Methods: We combined information from (1) the Fatality Analysis Reporting System (FARS), (2) a database compiled by the Consumer Product Safety Commission, and (3) a vehicle sales database. These aggregated data were used to describe trends, demographics, and frequent causes of serious injuries and fatalities.Results: On-road fatal crashes grew from 0 in the year 2000 to 37 in 2015; at the same time, sales grew from approximately 100,000 to 400,000 vehicles annually. Much of the increase in ROHV sales was in 2 new, higher performance classes of vehicles. Further, seat belt and helmet use in this cohort was rare (at least 46% unbelted, only 2% confirmed to be helmeted) and drinking and driving was common (57% of crashes in FARS). These vehicles appear to have increased potential for rollover, which often led unbelted occupants to be ejected, putting them at risk of being injured as the vehicle rolled on top of them.Conclusions: Serious ROHV crashes have grown with sales. Resulting injuries appear to be strongly influenced by inconsistent seat belt use, frequent drunk driving, and increased propensity for the vehicles to roll over.

Accident analysis to support the development of strategies for the prevention of brain injuries in car crashes

This study estimated the frequency and risk of Moderate-to-Maximal traumatic brain injuries sustained by occupants in motor vehicle crashes in the US. National Automotive Sampling System - Crashworthiness Data System crashes that occurred in years 2001–2015 with light vehicles produced 2001 or later were incorporated in the study. Crash type, crash severity, car model year, belt usage and occupant age and sex were controlled for in the analysis. The results showed that Moderate concussions account for 79% of all MAISbrain2+ injuries. Belted occupants were at lower risks than unbelted occupants for most brain injury categories, including concussions. After controlling for the effects of age and crash severity, belted female occupants involved in frontal crashes were estimated to be 1.5 times more likely to sustain a concussion than male occupants in similar conditions. Belted elderly occupants were found to be at 10.5 and 8 times higher risks for sub-dural haemorrhages than non-elderly belted occupants in frontal and side crashes, respectively. Adopted occupant protection strategies appear to be insufficient to achieve significant decreases in risk of both life-threatening brain injuries and concussions for all car occupants. Further effort to develop occupant and injury specific strategies for the prevention of brain injuries are needed. This study suggests that these strategies may consider prioritization of life-threatening brain vasculature injuries, particularly in elderly occupants, and concussion injuries, particularly in female occupants.

Driver and front passenger injury in frontal crashes: Update on the effect of unbelted rear occupants

ABSTRACTPurpose: This is a study of the influence of an unbelted rear occupant on the risk of severe injury to the front seat occupant ahead of them in frontal crashes. It provides an update to earlier studies.Methods: 1997–2015 NASS-CDS data were used to investigate the risk for severe injury (Maximum Abbreviated Injury Score [MAIS] 4+F) to belted drivers and front passengers in frontal crashes by the presence of a belted or unbelted passenger seated directly behind them or without a rear passenger. Frontal crashes were identified with GAD1 = F without rollover (rollover ≤ 0). Front and rear outboard occupants were included without ejection (ejection = 0). Injury severity was defined by MAIS and fatality (F) by TREATMNT = 1 or INJSEV = 4. Weighted data were determined. The risk for MAIS 4+F was determined using the number of occupants with known injury status MAIS 0+F. Standard errors were determined.Results: The risk for severe injury was 0.803 ± 0.263% for the driver with an unbelted left rear occupant and 0.100 ± 0.039% with a belted left rear occupant. The driver's risk was thus 8.01 times greater with an unbelted rear occupant than with a belted occupant (P <.001). With an unbelted right rear occupant behind the front passenger, the risk for severe injury was 0.277 ± 0.091% for the front passenger. The corresponding risk was 0.165 ± 0.075% when the right rear occupant was belted. The front passenger's risk was 1.68 times greater with an unbelted rear occupant behind them than a belted occupant (P <.001). The driver's risk for MAIS 4+F was highest when their seat was deformed forward. The risk was 9.94 times greater with an unbelted rear occupant than with a belted rear occupant when the driver's seat deformed forward. It was 13.4 ± 12.2% with an unbelted occupant behind them and 1.35 ± 0.95% with a belted occupant behind them.Conclusions: Consistent with prior literature, seat belt use by a rear occupant significantly lowered the risk for severe injury to belted occupants seated in front of them. The reduction was greater for drivers than for front passengers. It was 87.5% for the driver and 40.6% for the front passenger. These results emphasize the need for belt reminders in all seating positions.

Brainstem injury in motor vehicle crashes

ABSTRACTObjective: This is a descriptive study of the frequency and risk for brainstem injury by crash type, belt use, and crash severity (delta-V). NASS-CDS electronic cases were reviewed to see whether the transition from vehicles without advanced airbags and seat belts and side airbags and curtains to vehicles with the safety technologies has influenced the risk for brainstem injury.Methods: 1994–2013 NASS-CDS was analyzed to determine the number of brainstem injuries in nonejected adults (15+ years old) in vehicle crashes. Crashes were grouped by front, side, rear, and rollover. The effect of belt use was investigated. Light vehicles were included with model year (MY) 1994+. Occupants with severe head injury (Abbreviated Injury Scale [AIS] 4+) and Maximum Abbreviated Injury Scale (MAIS) 4+F injury were also determined. The risk for injury with standard errors was determined using the MAIS 0+F exposure by belt use and crash type. NASS-CDS electronic cases were studied with brainstem injury in 2001–2013 MY vehicles.Results: NASS-CDS indicates there are 872 ± 133 cases of brainstem injury per year. About 16.0% of AIS 4+ head injury involves the brainstem. For belted occupants, the highest risk for brainstem injury was in side impacts at 0.065 ± 0.010%. In contrast, the highest risk for brainstem injury was 0.310 ± 0.291% in rear impacts and 0.310 ± 0.170% in rollovers for unbelted occupants. The risk for brainstem injury increased with crash severity. The highest risk for brainstem injury was 3.54 ± 1.45% in crashes with >72 km/h (>45 mph) delta-V. Exponential functions fit the change in risk with delta-V. Eighteen NASS-CDS electronic cases showed that brainstem injury occurred in very severe collisions where the occupant experienced multiple injuries from intrusion or impact on vehicle structures stiffened by deformation.Conclusions: The risk for brainstem injury in belted occupants has remained essentially constant over 20 years, whereas the risk for MAIS 4+F injury has declined 38.3%. The prevention of brainstem injuries must address the extreme speed of collisions and weight mismatches that overwhelm structures, seat belts, frontal airbags, side airbags, and curtains in modern vehicles.

Does unbelted safety requirement affect protection for belted occupants?

ABSTRACTObjective: Federal regulations in the United States require vehicles to meet occupant performance requirements with unbelted test dummies. Removing the test requirements with unbelted occupants might encourage the deployment of seat belt interlocks and allow restraint optimization to focus on belted occupants. The objective of this study is to compare the performance of restraint systems optimized for belted-only occupants with those optimized for both belted and unbelted occupants using computer simulations and field crash data analyses.Methods: In this study, 2 validated finite element (FE) vehicle/occupant models (a midsize sedan and a midsize SUV) were selected. Restraint design optimizations under standardized crash conditions (U.S.-NCAP and FMVSS 208) with and without unbelted requirements were conducted using Hybrid III (HIII) small female and midsize male anthropomorphic test devices (ATDs) in both vehicles on both driver and right front passenger positions. A total of 10 to 12 design parameters were varied in each optimization using a combination of response surface method (RSM) and genetic algorithm. To evaluate the field performance of restraints optimized with and without unbelted requirements, 55 frontal crash conditions covering a greater variety of crash types than those in the standardized crashes were selected. A total of 1,760 FE simulations were conducted for the field performance evaluation. Frontal crashes in the NASS-CDS database from 2002 to 2012 were used to develop injury risk curves and to provide the baseline performance of current restraint system and estimate the injury risk change by removing the unbelted requirement.Results: Unbelted requirements do not affect the optimal seat belt and airbag design parameters in 3 out of 4 vehicle/occupant position conditions, except for the SUV passenger side. Overall, compared to the optimal designs with unbelted requirements, optimal designs without unbelted requirements generated the same or lower total injury risks for belted occupants depending on statistical methods used for the analysis, but they could also increase the total injury risks for unbelted occupants.Conclusions: This study demonstrated potential for reducing injury risks to belted occupants if the unbelted requirements are eliminated. Further investigations are necessary to confirm these findings.

A study into the kinematic response for unbelted human occupants during emergency braking

ABSTRACTSince January 2014 more vehicles are being fitted with new active safety systems facilitating vehicle collision avoidance or mitigation by reducing the kinetic energy prior to impact, the most common being autonomous emergency braking systems. Although beneficial in reducing crash energy these safety features may influence the occupant's posture within the cabin, and require special attention for the design and development of restraints system should the occupants be out of position or unbelted. This paper reviews the current reference volunteers’ physical test, proposed by Ejima, used to validate the unbelted kinematics of active human computer model and proposes a new set of generic biomechanical kinematic responses based on OM4IS sled test data, which are judged more representative to an unbelted occupant's reaction. New kinematics corridors for head and torso angular change in a typical 1 ‘g’ frontal scenario are provided.

Numerical parametric study on factors affecting passenger safety in motorcoach frontal collision

ABSTRACTThe paper presents the results of a numerical parametric study on the factors affecting passenger safety in a motorcoach frontal collision. The study is performed using the numerical model of the motorcoach sled test validated by the experimental data. The numerical model implements the rigid-body dynamics approach coupled with the finite-stiffness joints and deformable finite-element models of dummies. Three factors are parametrically studied: seating and restraint layout, seat stiffness and the shape of the input acceleration pulse. The positive effect of the seatbelt is demonstrated; the head injury criterion values for belted passenger do not exceed the safety limit for all considered seating layouts. The most dangerous seating layout is found to be the 50th percentile occupant with a 95th unbelted occupant sitting behind. Seat stiffness variation studies have shown the positive effect of plastic deformation in the seat structure. By varying the shape of the input acceleration pulse, the probability of a head injury is demonstrated to increase with the increase in the duration of maximum acceleration and time of its occurrence.

Adverse fetal outcome in road accidents: Injury mechanism study and injury criteria development in a pregnant woman finite element model

This study documents the development of adverse fetal outcome predictors dedicated to the analysis of road accidents involving pregnant women. To do so, a pre-existing whole body finite element model representative of a 50th percentile 26 weeks pregnant woman was used. A total of 8 accident scenarios were simulated with the model positioned on a sled. Each of these scenarios was associated to a risk of adverse fetal outcome based on results from real car crash investigations involving pregnant women from the literature. The use of airbags and accidents involving unbelted occupants were not considered in this study. Several adverse fetal outcome potential predictors were then evaluated with regard to their correlation to this risk of fetal injuries. Three predictors appeared strongly correlated to the risk of adverse fetal outcome: (1) the intra uterine pressure at the placenta fetal side area (r=0.92), (2) the fetal head acceleration (HIC) (r=0.99) and (3) area of utero-placental interface over a strain threshold (r=0.90). Finally, sensitivity analysis against slight variations of the simulation parameters was performed and assess robustness of these criteria.

Real-World Rib Fracture Patterns in Frontal Crashes in Different Restraint Conditions

Objective: The purpose of this study was to use the detailed medical injury information in the Crash Injury Research and Engineering Network (CIREN) to evaluate patterns of rib fractures in real-world crash occupants in both belted and unbelted restraint conditions. Fracture patterns binned into rib regional levels were examined to determine normative trends associated with belt use and other possible contributing factors.Methods: Front row adult occupants with Abbreviated Injury Scale (AIS) 3+ rib fractures, in frontal crashes with a deployed frontal airbag, were selected from the CIREN database. The circumferential location of each rib fracture (with respect to the sternum) was documented using a previously published method (Ritchie et al. 2006) and digital computed tomography scans. Fracture patterns for different crash and occupant parameters (restraint use, involved physical component, occupant kinematics, crash principal direction of force, and occupant age) were compared qualitatively and quantitatively.Results: There were 158 belted and 44 unbelted occupants included in this study. For belted occupants, fractures were mainly located near the path of the shoulder belt, with the majority of fractures occurring on the inboard (with respect to the vehicle) side of the thorax. For unbelted occupants, fractures were approximately symmetric and distributed across both sides of the thorax. There were negligible differences in fracture patterns between occupants with frontal (0°) and near side (330° to 350° for drivers; 10° to 30° for passengers) crash principal directions of force but substantial differences between groups when occupant kinematics (and contacts within the vehicle) were considered. Age also affected fracture pattern, with fractures tending to occur more anteriorly in older occupants and more laterally in younger occupants (both belted and unbelted).Conclusions: Results of this study confirmed with real-world data that rib fracture patterns in unbelted occupants were more distributed and symmetric across the thorax compared to belted occupants in crashes with a deployed frontal airbag. Other factors, such as occupant kinematics and occupant age, also produced differing patterns of fractures. Normative data on rib fracture patterns in real-world occupants can contribute to understanding injury mechanisms and the role of different causation factors, which can ultimately help prevent fractures and improve vehicle safety.

Evaluation of Vehicle-Based Crash Severity Metrics

Objective: Vehicle change in velocity (delta-v) is a widely used crash severity metric used to estimate occupant injury risk. Despite its widespread use, delta-v has several limitations. Of most concern, delta-v is a vehicle-based metric which does not consider the crash pulse or the performance of occupant restraints, e.g. seatbelts and airbags. Such criticisms have prompted the search for alternative impact severity metrics based upon vehicle kinematics. The purpose of this study was to assess the ability of the occupant impact velocity (OIV), acceleration severity index (ASI), vehicle pulse index (VPI), and maximum delta-v (delta-v) to predict serious injury in real world crashes.Methods: The study was based on the analysis of event data recorders (EDRs) downloaded from the National Automotive Sampling System / Crashworthiness Data System (NASS-CDS) 2000–2013 cases. All vehicles in the sample were GM passenger cars and light trucks involved in a frontal collision. Rollover crashes were excluded. Vehicles were restricted to single-event crashes that caused an airbag deployment. All EDR data were checked for a successful, completed recording of the event and that the crash pulse was complete. The maximum abbreviated injury scale (MAIS) was used to describe occupant injury outcome. Drivers were categorized into either non-seriously injured group (MAIS2−) or seriously injured group (MAIS3+), based on the severity of any injuries to the thorax, abdomen, and spine. ASI and OIV were calculated according to the Manual for Assessing Safety Hardware. VPI was calculated according to ISO/TR 12353-3, with vehicle-specific parameters determined from U.S. New Car Assessment Program crash tests. Using binary logistic regression, the cumulative probability of injury risk was determined for each metric and assessed for statistical significance, goodness-of-fit, and prediction accuracy.Results: The dataset included 102,744 vehicles. A Wald chi-square test showed each vehicle-based crash severity metric estimate to be a significant predictor in the model (p < 0.05). For the belted drivers, both OIV and VPI were significantly better predictors of serious injury than delta-v (p < 0.05). For the unbelted drivers, there was no statistically significant difference between delta-v, OIV, VPI, and ASI.Conclusions: The broad findings of this study suggest it is feasible to improve injury prediction if we consider adding restraint performance to classic measures, e.g. delta-v. Applications, such as advanced automatic crash notification, should consider the use of different metrics for belted versus unbelted occupants.

Estimated Injury Risk for Specific Injuries and Body Regions in Frontal Motor Vehicle Crashes

Objective: Injury risk curves estimate motor vehicle crash (MVC) occupant injury risk from vehicle, crash, and/or occupant factors. Many vehicles are equipped with event data recorders (EDRs) that collect data including the crash speed and restraint status during a MVC. This study's goal was to use regulation-required data elements for EDRs to compute occupant injury risk for (1) specific injuries and (2) specific body regions in frontal MVCs from weighted NASS-CDS data.Methods: Logistic regression analysis of NASS-CDS single-impact frontal MVCs involving front seat occupants with frontal airbag deployment was used to produce 23 risk curves for specific injuries and 17 risk curves for Abbreviated Injury Scale (AIS) 2+ to 5+ body region injuries. Risk curves were produced for the following body regions: head and thorax (AIS 2+, 3+, 4+, 5+), face (AIS 2+), abdomen, spine, upper extremity, and lower extremity (AIS 2+, 3+). Injury risk with 95% confidence intervals was estimated for 15–105 km/h longitudinal delta-Vs and belt status was adjusted for as a covariate.Results: Overall, belted occupants had lower estimated risks compared to unbelted occupants and the risk of injury increased as longitudinal delta-V increased. Belt status was a significant predictor for 13 specific injuries and all body region injuries with the exception of AIS 2+ and 3+ spine injuries. Specific injuries and body region injuries that occurred more frequently in NASS-CDS also tended to carry higher risks when evaluated at a 56 km/h longitudinal delta-V. In the belted population, injury risks that ranked in the top 33% included 4 upper extremity fractures (ulna, radius, clavicle, carpus/metacarpus), 2 lower extremity fractures (fibula, metatarsal/tarsal), and a knee sprain (2.4–4.6% risk). Unbelted injury risks ranked in the top 33% included 4 lower extremity fractures (femur, fibula, metatarsal/tarsal, patella), 2 head injuries with less than one hour or unspecified prior unconsciousness, and a lung contusion (4.6–9.9% risk). The 6 body region curves with the highest risks were for AIS 2+ lower extremity, upper extremity, thorax, and head injury and AIS 3+ lower extremity and thorax injury (15.9–43.8% risk).Conclusions: These injury risk curves can be implemented into advanced automatic crash notification (AACN) algorithms that utilize vehicle EDR measurements to predict occupant injury immediately following a MVC. Through integration with AACN, these injury risk curves can provide emergency medical services (EMS) and other patient care providers with information on suspected occupant injuries to improve injury detection and patient triage.

Seat Belt Usage in Injured Car Occupants: Injury Patterns, Severity and Outcome After Two Main Car Accident Mechanisms in Kashan, Iran, 2012.

Background:Road traffic accidents (RTAs) are the main public health problems in Iran. The seat belts, which are vehicle safety devices, are imperative to reduce the risk of severe injuries and mortality.Objectives:The aim of the study was to evaluate injury patterns, severity and outcome among belted and unbelted car occupants who were injured in car accidents.Patients and Methods:This cross-sectional prospective study was performed on all car occupants injured in RTAs (n = 822) who were transported to hospital and hospitalized for more than 24 hours from March 2012 to March 2013. Demographic profile of the patients, including age, gender, position in the vehicle, the use of seat belts, type of car crashes, injured body regions, revised trauma score (RTS), Glasgow coma score (GCS), duration of hospital stay and mortality rate were analyzed by descriptive analysis, chi-square and independent t-test. P < 0.05 was considered significant.Results:A total of 560 patients used seat belts (68.1%). The unbelted occupants were younger (28 years vs. 38 years) and had more frequently sustained head, abdomen and multiple injuries (P = 0.01, P = 0.01 and P = 0.009, respectively). Also, these patients had significantly lower GCS and elongated hospitalization and higher death rate (P = 0.001, P = 0.001 and P = 0.05, respectively). Tendency of severe head trauma and low RTS and death were increased in unbelted occupants in car rollover accident mechanisms (P = 0.001, P = 0.01 and P = 0.008, respectively).Conclusions:During car crashes, especially car rollover, unbelted occupants are more likely to sustain multiple severe injuries and death. Law enforcement of the seat belt usage for all occupants (front and rear seat) is obligatory to reduce severe injuries sustained as a result of car accidents, especially in vehicles with low safety.

Occupant and crash characteristics in thoracic and lumbar spine injuries resulting from motor vehicle collisions

Background contextMotor vehicle collisions (MVC) are a leading cause of thoracic and lumbar (T and L) spine injuries. Mechanisms of injury in vehicular crashes that result in thoracic and lumbar fractures and the spectrum of injury in these occupants have not been extensively studied in the literature. PurposeThe objective was to investigate the patterns of T and L spine injuries after MVC; correlate these patterns with restraint use, crash characteristics, and demographic variables; and study the associations of these injuries with general injury morbidity and fatality. Study design/settingThe study design is a retrospective study of a prospectively gathered database. Patient sampleSix hundred thirty-one occupants with T and L (T1–L5) spine injuries from 4,572 occupants included in the Crash Injury Research and Engineering Network (CIREN) database between 1996 and 2011 were included in this study. Outcome measuresNo clinical outcome measures were evaluated in this study. MethodsThe CIREN database includes moderate to severely injured occupants from MVC involving vehicles manufactured recently. Demographic, injury, and crash data from each patient were analyzed for correlations between patterns of T and L spine injuries, associated extraspinal injuries and overall injury severity score (ISS), type and use of seat belts, and other crash characteristics. T and L spine injuries patterns were categorized using a modified Denis' classification to include extension injuries as a separate entity. ResultsT and L spine injuries were identified in 631 of 4,572 vehicle occupants, of whom 299 sustained major injuries (including 21 extension injuries) and 332 sustained minor injuries. Flexion-distraction injuries were more prevalent in children and young adults and extension injuries in older adults (mean age, 65.7 years). Occupants with extension injuries had a mean body mass index of 36.0 and a fatality rate of 23.8%, much higher than the fatality rate for the entire cohort (10.9%). The most frequent extraspinal injuries (Abbreviated Injury Scale Grade 2 or more) associated with T and L spine injuries involved the chest (seen in 65.6% of 631 occupants). In contrast to occupants with major T and L spine injuries, those with minor T and L spine injuries showed a strikingly greater association with pelvic and abdominal injuries. Occupants with minor T and L spine injuries had a higher mean ISS (27.1) than those with major T and L spine injuries (25.6). Among occupants wearing a three-point seat belt, 35.3% sustained T and L spine injuries, whereas only 11.6% of the unbelted occupants sustained T and L spine injuries. Three-point belted individuals were more likely to sustain burst fractures, whereas two-point belted occupants sustained flexion-distraction injuries most often and unbelted occupants had a predilection for fracture-dislocations of the T and L spines. Three-point seat belts were protective against neurologic injury, higher ISS, and fatality. ConclusionsT and L spine fracture patterns are influenced by the age of occupant and type and use of seat belts. Despite a reduction in overall injury severity and mortality, seat belt use is associated with an increased incidence of T and L spine fractures. Minor T and L spine fractures were associated with an increased likelihood of pelvic and abdominal injuries and higher ISSs, demonstrating their importance in predicting overall injury severity. Extension injuries occurred in older obese individuals and were associated with a high fatality rate. Future advancements in automobile safety engineering should address the need to reduce T and L spine injuries in belted occupants.

Spinal Fracture-Dislocations and Spinal Cord Injuries in Motor Vehicle Crashes

Purpose: This study estimated the annual count of spinal cord injuries (SCIs) in motor vehicles crashes by type and seat belt use using 18 years of NASS-CDS data. It determined the rate for SCI and fracture-dislocation of the spine.Methods: 1994–2011 NASS-CDS was used to estimate the annual occurrence of spinal injuries in front seat occupants involved in motor vehicle crashes. Crashes were grouped by front, side, rear, and rollovers, and the effects of belt use were investigated. Light vehicles were included with model year 1994+. Spinal injuries were classified as minor (Abbreviated Injury Scale [AIS] 1), moderate (AIS 2), serious (AIS 3), fracture-dislocations, and SCI (AIS 4+). The annual count and rate for different types of spinal injury were estimated along with standard errors. The results were compared to estimates of head injuries. NASS-CDS electronic cases of SCIs in rear impacts were investigated.Results: There were 5,592 ± 1,170 fracture-dislocations of the spine and 1,046 ± 193 AIS 4+ SCI per year in motor vehicle crashes. Most of the injuries occurred in rollovers and frontal crashes and the least occurred in rear impacts. The rate of SCI was 0.054 ± 0.010%. The highest rate was 0.220 ± 0.056% in rollover crashes and the lowest rate was 0.032 ± 0.009% in frontal crashes. The highest rate for spinal fracture-dislocation was 1.552 ± 0.455% in rollovers and the lowest was 0.065 ± 0.021% in rear impacts. The rate for SCI was 0.027 ± 0.005% in belted and 0.145 ± 0.028% in unbelted occupants giving 81% effectiveness of belt use in reducing SCI. The cervical spine was associated with 66.3 ± 11.3% of the AIS 4+ SCI with 30.5 ± 7.4% in the thoracic spine and 3.2 ± 1.3% in the lumbar spine. Severe head injuries occurred 13.3 times more often than SCIs.Conclusions: Spinal cord injury occurred in one out of 1,860 front seat occupants in tow-away crashes. The rate was highest in rollover crashes and was reduced by seat belt use. Fracture-dislocation of the spine occurred about 5.3 times more often than SCIs and was also prevented by seat belt use.

Occupant Kinematic Study in Safe Bus Superstructure

The risk of injuries and fatalities is severe when bus superstructure fails during rollover accidents. This study deals with two stages of analyses which are superstructure strength having rollover analysis and occupants kinematic analysis. The validation process by correlating the strain results obtained from simple box rollover and simulation process done. The inputs from validation process had been used for full-scale bus superstructure rollover. A complete bus structure was developed and simulation was done according to the United Nation Economic Commission of Europe (UNECE) regulation 66 by utilizing finite element analysis software. Injury to occupant at various locations was studied as well as comparison study between belt occupant and unbelted occupants by using the Mathematical Dynamic Model (MADYMO) software. Analysis suggested that superstructure strength and occupant kinematics consideration can reduce fatality and serious injury in bus rollover accident.

Attitudes Toward Seat Belt Use and In-Vehicle Technologies for Encouraging Belt Use

Objectives: In-vehicle seat belt reminders and interlocks can encourage belt use, but widespread adoption of these features depends on the degree of acceptance among both belted and unbelted occupants. The current study collected information about attitudes toward belt use and in-vehicle technologies for encouraging belt use. Methods: A national telephone survey of 1218 adult drivers and passengers was conducted using random samples of landline and cell phone numbers. Part-time belt users and nonusers were oversampled. All respondents were asked about frequency of belt use, buckling routines, and support for different types of belt interlocks. Part-time belt users and nonusers were queried in more depth about different types of reminders and reminder strategies. Results: Almost all respondents said that they always use their seat belts (91%). Few said that they did not always (8%) or never (1%) used belts. Driving a short distance (67%), forgetting (60%), and comfort (47%) were common reasons why part-time belt users do not buckle up; comfort (77%), not needing a seat belt (54%), and disliking being told what to do (50%) were most frequently cited among nonusers. When asked about various types of belt interlocks, part-time belt users and nonusers most often said that ignition interlocks would make them more likely to buckle up (70% and 44%, respectively). However, only 44 to 51 percent of all respondents, including full-time belt users, supported using the different types of interlocks to increase belt use. A larger proportion of part-time belt users and nonusers said that they would be more likely to buckle up in response to auditory and haptic reminders than visual reminders. More than two thirds of part-time belt users and at least one third of nonusers said that they would be more likely to buckle up in response to belt reminders that become more intense or continue indefinitely; these reminders would be acceptable to about half of part-time belt users and around one fifth of nonusers. Conclusions: The Moving Ahead for Progress in the 21st Century (MAP-21) law allows the National Highway Traffic Safety Administration to strengthen minimum requirements for belt reminders or allow the use of interlocks to meet federal safety standards. Even though most people always buckle up, belt interlocks are supported by only about half of full-time belt users and by fewer part-time belt users and nonusers. Enhanced reminder systems are more acceptable than belt interlocks and are viewed as almost as effective as interlocks if persistent enough. Supplemental materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention to view the supplemental file.