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Injury Risks in Frontal Crashes by Delta V and Body Region With Focus on Head Injuries in Low-Speed Collisions
Traffic Injury Prevention
Abstract
This study investigated injury risks in frontal crashes by belt use and crash severity (delta V) with a focus on studying whether there is a pattern to the crashes causing serious head injuries in low-speed frontal collisions.
1996-2007 National Automotive Sample System-Crashworthiness Data System (NASS-CDS) was analyzed for frontal crashes involving front-outboard occupants. Light vehicles were included with model year 1997+. Injuries of maximum severity MAIS 0-6 and fatalities were determined by crash severity and belt. Body region injury (AIS 0-6) was also determined. NASS-CDS electronic cases involving <15 mph crashes were evaluated to determine the crash circumstances causing serious head injury (AIS 3+) in occupants with overall severe injuries (MAIS 4+F).
More than half (51.3%) of belted occupants in 10-15 mph delta V crashes were uninjured compared with 30.2 percent for unbelted occupants. The ratio of the fraction (relative risk) of belted occupants who were uninjured to the fraction of unbelted, uninjured occupants was highest at 3.74 in the 30-35 mph delta V. For 10-15 mph crashes, 0.40 +/- 0.15 percent of unbelted occupants were severely injured (MAIS 4+F) compared to 0.033 +/- 0.009 percent for belted occupants. For 30-35 mph crashes, 8.51 +/- 2.20 percent of unbelted and 5.83 +/- 1.93 percent of belted occupants were severely injured. Overall, seat belt use was 87.4 percent effective in preventing severe injury (MAIS 4+F). The effectiveness decreased with increasing crash severity. The highest relative risk for severe injury of unbelted compared to belted occupants was 12.3 in crashes of 10-15 mph delta V. The relative risk was 8.8 in <10 mph crashes. Overall, the relative risk was 8.0 for severe injury (MAIS 4+F) in frontal crashes. 16.5 +/- 0.98 percent of unbelted occupants experienced serious (AIS 3-6) injury. This risk was 6.49 times greater than the 2.53 +/- 0.10 percent risk with belted occupants. The largest relative risk for serious injury (AIS 3-6) was to the neck (367 times), face (15.5 times) and head (10.2 times).
The highest relative risk for severe injury of unbelted occupants was in frontal crashes <15 mph. Most of the crashes involved multiple impacts and air bag deployment in the accident sequence. The use of long fill-time side curtains, additional curtain deployment logic, limited deflation front air bags and broader curtain coverage of the front interior may address these injuries.
... Earlier published studies not focusing on advanced airbags showed that serious injuries were likely to occur at delta Vs above about 60 km/h, despite airbag deployment and belt use [11,12]. Viano and Parenteau [13] reported that the rate of serious injury (MAIS3+F) for a belted front occupant with front airbag deployment in 1997-2007 model year vehicles was approximately 75% in a frontal collision with delta V of 64-72 km/h. Of note, all of these prior studies involved vehicle models produced before the complete rollout of advanced restraint technologies. ...
... The data from this study also showed that more than 10% of front-seat occupants sustained a serious-to-fatal injury at delta Vs less than 24 km/h. Viano and Parenteau [13] reviewed NASS-CDS electronic cases involving severely injured front-seat occupants involved in frontal crashes with a delta V less than 24 km/h. They noted that most crashes at these speeds that met the inclusion criteria for NASS CDS involved multiple impacts; additional impacts may have occurred after airbag deployment, and/or occupants may have been out-of-position at the time of an injurious impact. ...
... The results of this study continue to support that lap-shoulder belts are effective in reducing injury rates, consistent with prior work [13,14,15]. Despite this fact, lap and shoulder belts, even with pretensioners and load limiters, do not prevent all serious injuries. ...
... Earlier published studies not focusing on advanced airbags showed that serious injuries were likely to occur at delta Vs above about 60 km/h, despite airbag deployment and belt use [11,12]. Viano and Parenteau [13] reported that the rate of serious injury (MAIS3+F) for a belted front occupant with front airbag deployment in 1997-2007 model year vehicles was approximately 75% in a frontal collision with delta V of 64-72 km/h. Of note, all of these prior studies involved vehicle models produced before the complete rollout of advanced restraint technologies. ...
... The data from this study also showed that more than 10% of front-seat occupants sustained a serious-to-fatal injury at delta Vs less than 24 km/h. Viano and Parenteau [13] reviewed NASS-CDS electronic cases involving severely injured front-seat occupants involved in frontal crashes with a delta V less than 24 km/h. They noted that most crashes at these speeds that met the inclusion criteria for NASS CDS involved multiple impacts; additional impacts may have occurred after airbag deployment, and/or occupants may have been out-of-position at the time of an injurious impact. ...
... The results of this study continue to support that lap-shoulder belts are effective in reducing injury rates, consistent with prior work [13,14,15]. Despite this fact, lap and shoulder belts, even with pretensioners and load limiters, do not prevent all serious injuries. ...
This study updated injury information in frontal collisions for current restraint technology. First, the rate of serious-to-fatally (MAIS3+F) injured lap-shoulder belted front-seat occupants involved in frontal motor vehicle crashes with airbag deployment was determined by model year groups as a function of frontal airbag regulatory changes (1989-1998, 1999-2005, and 2006+) using 1994-2015 NASS-CDS. The results a trend for reductions in injury rates with modern restraint technology. Second, the distribution of exposed (MAIS 0+F) and serious-to-fatally (MAIS3+F) injured front seat occupants was assessed by crash severity for 2006+ MY vehicles equipped with modern technologies. Injury rates were also determined as a function of belt use to estimate belt effectiveness. The results showed that the rate of MAIS3+F injury increased with the vehicle's change in velocity. However, there was a marked increase in injury rate with delta V 64+ km/h compared to lower-severity crashes. Injury rates were consistently lower for belted than unbelted occupants, though seat belt effectiveness decreased from approximately 70% to 42% as delta V increased from 20 to 76 km/h. In a third part of the study, an in-depth case review was conducted to identify the circumstances of frontal collisions resulting in fatality despite availability of advanced restraint systems, including severe crash conditions or a frail front occupant.
... Many researchers have investigated the relationship between velocity and the risk of injury to occupants and have posited numerous relationships between velocity and risk from the literature to their studies [17][18] [19]. Gabauer and Gabler [20] studied the maximum injury and chest injuries of occupants according to the delta-v from event data recorders (EDRs) via a binary logistic regression for MAIS3+ injuries using the NHTSA EDR database. ...
... Kusano and Gabler [14] created two risk functions for belted occupants and unbelted occupants through a logistic regression based on the NASS/CDS database. Viano and Parenteau [17] determined the discrete line-of-injury risk with the fraction of injured occupants according to the delta-v obtained from the NASS/CDS database. As shown above, the relationship between injury risks and relative velocities in crashes has been studied thoroughly. ...
One of the recent developments in safety systems is an external airbag installed on the front bumper of a vehicle and autonomous emergency braking system. In this paper, we propose a framework for a cost-benefit analysis of the external airbag and autonomous emergency braking system in order to validate its commercialization. Road traffic crash data obtained from the National Automotive Sampling System/Crashworthiness Data System (NASS/CDS) was used, and three different crash types related to frontal damage in vehicles were extracted to estimate the safety performance of an external airbag. An ordinal logistic regression model was applied to estimate the safety performance in terms of the reduced maximum abbreviated injury scale (MAIS) based on a reduction in the total delta-v following the installation of an external airbag. Given the estimated safety performance of the external airbag, a cost-benefit analysis is conducted. According to the results, the external airbag system saves 46% of occupants with MAIS 3+ injuries and prevents 40% of fatalities. Moreover, the benefit/cost ratios of the external airbag system range from 0.496 to 0.509 depending on the scenario. Lastly, sensitivity analyses were performed with important parameters, including the initial and maximum market penetration ratio and the price of the system.
... Furthermore, we found that in 13 cases the MVs were older passenger cars lacking side airbags and side curtain airbags, which probably contributed to the injury severity in side impacts. Such airbags help mitigate impacts to the head, chest, abdomen, and pelvis since they provide coverage of the A-pillar, B-pillar, and side roof rail, and further serve as a containment barrier to prevent partial or complete ejection from the MV [33]. Moreover, older MVs also do not include modern crash-avoidance systems, and 81% of the MVs in the current study were older than 10 years. ...
Purpose
We performed a multidisciplinary investigation of young adults involved in motor vehicle collisions (MVCs) to elucidate injury mechanisms and the role of passive safety equipment such as seat belts and airbags.
Methods
MVCs resulting in death or serious injuries to the driver or passengers aged 16–24 years in southeastern Norway during 2013–2016 were investigated upon informed consent. We assessed the crash scene, the motor vehicle (MV) interior and exterior, and analyzed data from medical records, forensic autopsies and reports from police and civil road authorities.
Results
This study included 229 young adult occupants involved in 212 MVCs. The Maximum Abbreviated Injury Scale (MAIS) score was ≥2 in 111 occupants, of which 22 were fatalities. In 59% (65/111) of the cases with MAIS score ≥2 injuries, safety errors and occupant protection inadequacies were considered to have contributed to the injury outcome. Common errors were seatbelt non-use and misuse, carrying insecure luggage, and the seat back being too reclined. MAIS score ≥2 head/neck injuries were observed in side impacts despite correct seatbelt use, related to older MVs lacking side airbag curtains. The independent risk factors for MAIS score ≥2 injuries included not using a seatbelt, driving under the influence of alcohol or drugs, nighttime driving, side impacts, heavy collision partner, and MV deformation.
Conclusion
User safety errors (not using a seatbelt, seatbelt misuse, excessive seat-back reclining, and insecure cargo) and a lack of occupant protection in older MVs resulted in young adults sustaining severe or fatal injuries in MVCs.
... Female drivers over age 65 had a higher percentage of overall fatal crash rates than males in 2019 (NHTSA, 2021a;2019 Data Traffic Safety Facts, 813121). Crashes of younger drivers, attributed largely to speeding (Shannon et al., 2020), tend to be more severe as measured with delta-V (change in vehicle velocity over the duration of the crash event) related to patterns of injury (Sunnevang et al., 2009;Viano and Parenteau, 2010;Shannon et al., 2020). However, the fragility associated with advanced age leads to greater injury and death when older people are involved in crashes (Hakamies-Blomqvist and Davidse, 2004;Calvo et al., 2020). ...
Automobile crashes are a leading cause of death in the United States and worldwide. Driver automation systems and active safety systems have the potential to improve the safety and mobility of all road users and may particularly benefit older adults who have been slow to accept and adopt such systems. Age-related sensory-cognitive changes contribute to higher crash rates and increased physical frailty makes severe injury or death more likely when a crash occurs. Vehicle automation can decrease the sensory-cognitive load of the driving task and many advanced automated safety features can decrease crash severity. Acceptance and adoption of driver automation systems is necessary for their benefit to be realized yet little is known about drivers’ preferred sources of information and knowledge about such systems. In a sample of 404 active drivers, we examined the impact of age and gender on understanding and acceptance of vehicle automation, acceptance of new technologies more generally, and preferred sources of information to learn about vehicle automation. Results revealed that older respondents and females felt less technically sophisticated than their younger and male counterparts. Males subjectively reported greater understanding of vehicle automation. However, assessment of objective knowledge of automation operation showed males had no greater knowledge than females. Males also reported a greater willingness to accept higher levels of vehicle automation than females across all age groups. When asked how they would prefer to learn about new vehicle automation, older adults reported wanting information from more objective sources than their younger counterparts and were significantly less likely to rely on friends and family, or social media. The present results provide support for the idea that people are not willing to accept technology that they do not feel they understand well and conversely, if people feel that they understand vehicle automation they will be more likely to adopt it. The results provide insights into assisting drivers to gain more accurate knowledge and hence acceptance of vehicle automation systems.
... Female drivers over age 65 had a higher percentage of overall fatal crash rates than males in 2019 (NHTSA, 2021a;2019 Data Traffic Safety Facts, 813121). Crashes of younger drivers, attributed largely to speeding (Shannon et al., 2020), tend to be more severe as measured with delta-V (change in vehicle velocity over the duration of the crash event) related to patterns of injury (Sunnevang et al., 2009;Viano and Parenteau, 2010;Shannon et al., 2020). However, the fragility associated with advanced age leads to greater injury and death when older people are involved in crashes (Hakamies-Blomqvist and Davidse, 2004;Calvo et al., 2020). ...
Advanced driver assistance systems (ADAS) in passenger vehicles can improve highway safety. ADAS place powerful, yet imperfect, automation in the hands of drivers who hold both misconceptions and reservations about ADAS. There is little previous research on drivers’ knowledge of ADAS, and even less on sources of information drivers use to inform their knowledge. The present study addressed this gap, testing hypotheses about influences on understanding of seven ADAS in 634 licensed US drivers (aged 18–82). Multiple regression to predict self-assessed driver characteristics revealed: (a) Drivers who rated themselves as more technically sophisticated tended to be young and male, to be at once less objectively knowledgeable and more confident of their knowledge of ADAS, to avoid car dealers for ADAS information, and to value brand status; (b) Drivers who rated themselves as faster to adopt new technology also tended to be male but to be more objectively knowledgeable about ADAS and to prefer learning about ADAS from owner manuals; (c) Drivers who rated themselves as more confident in using novel vehicle technology tended to be young males with greater objective knowledge of ADAS who valued “hands-on” ADAS experience; (d) Drivers who rated themselves as more concerned about vehicle safety tended to be female, to value crash data, and to rely on hands-on experience to learn about ADAS; (e) Drivers who rated themselves as having greater aesthetic concerns tended to rely on information on styles, colors, wheels when buying a new car and preferred specific ADAS components. Neither of the latter two differed in objective ADAS knowledge. These results make a novel contribution in revealing how driver demographics and characteristics are related to preference for specific sources of information on ADAS and objective knowledge of ADAS. These results can inform future efforts to increase driver understanding of the capabilities and limitations of ADAS and hence increase public safety.
... Delta-V relates to overall injury severity. 14,31,32 Delta-V in this study is of the vehicle or VRU overall, not the delta-V local body region (e.g. head), which can vary based on the specific kinematics of the collision. ...
Road traffic collisions are a major cause of traumatic brain injury. However, the relationship between road traffic collision dynamics and traumatic brain injury risk for different road users is unknown. We investigated 2,065 collisions from Great Britain’s Road Accident In-depth Studies collision database involving 5,374 subjects (2013-20). 595 subjects sustained a traumatic brain injury (20.2% of 2,940 casualties), including 315 moderate-severe and 133 mild-probable. Key pathologies included skull fracture (179, 31.9%), subarachnoid haemorrhage (171, 30.5%), focal brain injury (168, 29.9%) and subdural haematoma (96, 17.1%). These results were extended nationally using >1,000,000 police-reported collision casualties. Extrapolating from the in-depth data we estimate that there are ∼20,000 traumatic brain injury casualties (∼5,000 moderate-severe) annually on Great Britain’s roads, accounting for severity differences. Detailed collision investigation allows vehicle collision dynamics to be understood and the change-in-velocity (known as delta-V) to be estimated for a subset of in-depth collision data. Higher delta-V increased the risk of moderate-severe brain injury for all road users. The four key pathologies were not observed below 8km/h delta-V for pedestrians/cyclists and 19km/h delta-V for car occupants (higher delta-V threshold for focal injury in both groups). Traumatic brain injury risk depended on road user type, delta-V and impact direction. Accounting for delta-V, pedestrians/cyclists had a 6-times higher likelihood of moderate-severe brain injury than car occupants. Wearing a cycle helmet was protective against overall and mild-to-moderate-severe brain injury, particularly skull fracture and subdural haematoma. Cycle helmet protection was not due to travel or impact speed differences between helmeted and non-helmeted cyclist groups. We additionally examined the influence of delta-V direction. Car occupants exposed to a higher lateral delta-V component had a greater prevalence of moderate-severe brain injury, particularly subarachnoid haemorrhage. Multivariate logistic regression models created using total delta-V value and whether lateral delta-V was dominant had the best prediction capabilities (area under the receiver operator curve as high as 0.95). Collision notification systems are routinely fitted in new cars. These record delta-V and automatically alert emergency services to a collision in real-time. These risk relationships could therefore inform how routinely fitted automatic collision notification systems alert the emergency services to collisions with a high brain injury risk. Early notification of high-risk scenarios would enable quicker activation of the highest level of emergency service response. Identifying those that require neurosurgical care and ensuring they are transported directly to a centre with neuro-specialist provisions could improve patient outcomes.
... A study conducted by Afukaar [51] reported that speeding was highly associated with fatal injuries because the high impact force exceeds human tolerance. Other studies have revealed that drivers involved in head-on crashes are more likely to sustain head, cervical, and chest injuries [52][53][54][55], which generally lead to unfavourable trauma outcomes. ...
Background:
Studies have suggested that trauma centre-related risk factors, such as distance to the nearest trauma hospital, are strong predictors of fatal injuries among motorists. Few studies have used a national dataset to study the effect of trauma centre-related risk factors on fatal injuries among motorists and motorcyclists in a country where traffic is dominated by motorcycles. This study investigated the effect of distance from the nearest trauma hospital on fatal injuries from two-vehicle crashes in Taiwan from 2017 to 2019.
Methods:
A crash dataset and hospital location dataset were combined. The crash dataset was extracted from the National Taiwan Traffic Crash Dataset from 1 January 2017 through 31 December 2019. The primary exposure in this study was distance to the nearest trauma hospital. This study performed a multiple logistic regression to calculate the adjusted odds ratios (AORs) for fatal injuries.
Results:
The multivariate logistic regression models indicated that motorcyclists involved in crashes located ≥5 km from the nearest trauma hospital and in Eastern Taiwan were approximately five times more likely to sustain fatal injuries (AOR = 5.26; 95% CI: 3.69-7.49).
Conclusions:
Distance to, level of, and region of the nearest trauma centre are critical risk factors for fatal injuries among motorcyclists but not motorists. To reduce the mortality rate of trauma cases among motorcyclists, interventions should focus on improving access to trauma hospitals.
... Due to the high impact force that exceeds the human body threshold, speeding is highly correlated with fatal injuries [60]. In addition, drivers involved in a head-on crash were more likely to suffer head, chest and neck injuries [61][62][63][64]. ...
Background:
Research suggests that drivers tend to engage in risk-taking behaviours on public holidays. Studies that examined the association between holidays (or other special days) and fatal injuries are inconsistent. This study used UK STATS19 data to investigate the associations of nine public holidays on road crash casualties.
Methods:
This retrospective study assessed UK STATS19 crash data for 1990-2017. All casualties from two vehicle crashes were initially considered; subsequently, casualties with missing data were excluded. Multiple logistic regression was estimated to explore the associations of potential risk factors with the likelihood of killed or seriously injured (KSI) casualties and to calculate adjusted odds ratios (AORs).
Results:
In total, 3,751,998 casualties from traffic accidents in the United Kingdom during 1990-2017 were included in the final data set; among these, 410,299 (10.9%) were KSI casualties, and 3,341,699 (89.1%) were slight injuries. Crashes on public holidays were 16% (AOR = 1.16; 95% confidence interval [CI] = 1.13-1.19) more likely to involve KSI casualties than were crashes on non-holidays. With other factors controlled for, crashes during the Queen's 2002 Golden Jubilee and on New Year's Day were 48% (AOR = 1.48; 95% CI = 1.06-2.07) and 36% (AOR = 1.36; 1.26-1.48) more likely to lead to KSIs, respectively.
Conclusions:
The proportion of crashes resulting in KSI casualties on public holidays was higher than that on non-holidays. Furthermore, crashes during the Queen's 2002 Golden Jubilee had the highest risk of KSI casualties followed by New Year's Day.
... Speeding is highly associated with fatal injuries due to the high impact force that surpasses human tolerance (Afukaar, 2003). Also, drivers involved in head-on crashes are more likely to sustain head, chest, and cervical injuries (Lin et al., 2004;Ooi et al., 2011;Viano and Parenteau, 2010;Yu et al., 2011). ...
Background
Alcohol-involved riders tend to engage in other risk-taking behaviours such as un-helmeted riding which could further increases injury severity. The combined effect of alcohol-involved and un-helmeted riding on fatal injuries is rarely investigated. This study investigated the interaction effect between blood alcohol concentration and helmet use on fatal injuries.
Methods
This study used the National Taiwan Traffic Crash Dataset for the period from 2011 to 2015. Data on road crashes involving a motorcycle and an automobile were extracted and analysed. Multiple logistic regression models were used to calculate the adjusted odds ratio (AOR). We calculated an interaction effect for blood alcohol concentration and helmet use based on STROBE guidelines.
Results
There were a total of 669,292 motorcyclist casualties; among these casualties, 3459 (0.5 %) motorcyclists sustained fatal injuries. Alcohol-involved riders were 9.47 times (AOR = 9.47; 95 % CI = 8.75–10.25) more likely than sober ones to sustain fatal injuries. Alcohol-involved and un-helmeted riders were approximately 18 times (AOR = 18.1; CI: 15.9–20.4) more likely to sustain fatal injuries than sober and helmeted riders. Riders involved in head-on crashes and approach-turn motorcycle crashes had an increased probability of sustaining fatal injuries by 240 % (AOR = 3.4; 95 % CI = 2.91–4.09) and 132 % (AOR = 2.3; 95 % CI = 2.016–2.67), respectively.
Conclusions
This study found that alcohol-involved riding acts synergistically with un-helmeted riding to increase motorcyclist injury severity.
... Part-time belt users cite other reasons for not always using a seat belt besides forgetfulness, such as taking a short trip (Boyle & Lampkin, 2007;Kidd et al., 2014). Belt use during short trips on and off public roadways (e.g., parking lots, private drives) is important considering that crash injury risk is elevated for unrestrained occupants relative to restrained ones even at low speeds (Viano & Parenteau, 2010). However, part-time belt users may be willing to tolerate visual and auditory signals from a seat belt reminder system when traveling on short trips unbelted, thereby limiting the efficacy of this technology. ...
Introduction:
Vehicle technologies that increase seat belt use can save thousands of lives each year. Kidd, Singer, Huey, and Kerfoot (2018) found that a gearshift interlock was more effective for increasing seat belt use than an intermittent audible reminder, but interlocks may not be more effective than persistent audible reminders lasting at least 90 seconds.
Method:
Forty-nine part-time belt users with a recent seat belt citation who self-reported not always using a seat belt drove two vehicles for 1 week each. Thirty-three drove a Chevrolet with an intermittent audible reminder followed by either a BMW with a persistent 90-second audible reminder (n = 17) or a Subaru with an incessant audible reminder (n = 16). The other 16 participants experienced the BMW persistent reminder followed by an interlock that limited speed to 15 mph during unbelted driving. These data were combined with data from 32 part-time belt users in Kidd et al. (2018) who experienced the intermittent reminder for 2 weeks or the intermittent reminder for 1 week and a gearshift interlock the next.
Results:
Relative to the intermittent reminder, seat belt use was significantly increased an estimated 30% by the BMW persistent reminder, 34% by the Subaru incessant reminder, and 33% by the speed-limiting interlock. Belt use was increased an estimated 16% by the gearshift interlock, but this change was not significant. More participants circumvented the speed-limiting interlock to drive unbelted than the audible reminders. Responses to a poststudy survey indicated that interlocks were less acceptable than reminders.
Conclusions:
Audible reminders lasting at least 90 seconds and a speed-limiting interlock were more effective for increasing seat belt use than an intermittent audible reminder, but reminders were found more acceptable. Practical applications: Strengthening existing U.S. safety standards to require audible reminders lasting at least 90 seconds for front-row occupants could save up to 1,489 lives annually.
... Of the injuries suffered in vehicular impacts, head injuries, mostly commonly due to impacts with the vehicle interior, are some of the most frequently observed injuries suffered by vehicle occupants. Such injuries are most commonly found in the frontal and lateral impacts (Augenstein et al. 2000;Farmer et al. 1997;Kuppa et al. 2001;Viano and Parenteau 2010). In rear impacts, the neck is most frequent site of injury, with more than 80% of injuries suffered in rear impacts being cervical whiplash (Ono and Kanno 1996). ...
Due to the increased number of fatalities and injuries in motor vehicle accidents, it is crucial to study the kinematic and kinetic occupant response during collisions, specifically the head and neck response due to their vulnerable nature. In Part I we have addressed rear end collisions. In Part II we examine occupant response in frontal and lateral collisions. Two multibody dynamics models of the cervical spine of the 50th percentile male were developed and validated. The cervical spine was modeled as a series of rigid links connected through single and two degrees of freedom viscoelastic joints. In addition, finite element simulations of two compact sedan vehicle were conducted to capture realistic crash acceleration of the driver seat in frontal and lateral collision scenarios. Furthermore, finite element simulations were performed to capture the kinematic and kinetic response of a seated restrained male occupant subjected to the realistic seat accelerations in frontal and lateral collisions. Finally, the possibility of injury in frontal, lateral and rear collisions was evaluated. The evaluation of ligament injury risk shows high risk of injury at the interspinous ligament in frontal collision, at the anterior longitudinal ligament in rear collision and at the near-side capsular ligament in lateral collision. The highest vertebral fracture risks were found at the mid- and lower cervical spine in rear and lateral collisions. The outcomes of this work provide a better understanding of occupant injury mechanism during frontal, lateral and rear collisions which is essential to enhancing motor vehicle safety.
... Several studies have investigated the influence of specific risk factors or countermeasures on injury severity among motorcyclists. However, research showing an accurate relation between travelling speed (or change of velocity during a motorcycle crash) and injury outcome among motorcyclists remains sparse, although such a relationship has been extensively investigated for car occupants (Gabauer and Gabler, 2006;Hampton and Gabler, 2009;Kusano and Gabler, 2011;Richards and Cuerden, 2009;Viano and Parenteau, 2010;Weaver et al., 2015), and pedestrians (Kröyer et al., 2014;Rosén et al., 2011;Tefft, 2013). ...
The Vision Zero approach advocates for a road transport system designed with human injury tolerance and human fallibility as its basis. While biomechanical limits and the relationship between speed and injury outcome has been extensively investigated for car occupants and pedestrians, research analyzing this relationship for motorcyclists remains limited. The aim of this study was to address this issue by developing multivariate injury risk models for motorcyclists that estimate the relationship between speed and injury severity. For that purpose, motorcycle injury crashes from the German In-Depth Accident Study (GIDAS) database for the period 1999–2017 (n = 1037) were extracted. Different models were tested using logistic regression and backwards elimination of non-significant variables. The best fitting model in the current study included relative speed, type of crash opponent, impact location on the motorcycle and impact mechanism of the rider during the crash. A strong and significant relationship between relative speed and injury severity in motorcycle crashes was demonstrated. At 70 km/h, the risk for at least serious injuries in collisions with wide objects, crash barriers and narrow objects was 20%, 51%, and 64%, respectively. Further, it was found that head-on collisions between motorcycles and passenger cars, with both vehicles traveling at 60 km/h (a relative speed at 120 km/h), present 55% risk of at least serious injury to the motorcycle rider. More research is needed to fully understand the boundary conditions needed to design a safe road transport system for motorcyclists. However, this study provides important insights into the relationship between speed and injury severity for riders in various crash situations. The results may be useful in the discussion of appropriate speed limits and in determining the benefits of countermeasures which aim to reduce crash speed.
... Part-time belt users cite other reasons for not always using a seat belt besides forgetfulness, such as taking a short trip (Boyle & Lampkin, 2007;Kidd et al., 2014). Belt use during short trips on and off public roadways (e.g., parking lots, private drives) is important considering that crash injury risk is elevated for unrestrained occupants relative to restrained ones even at low speeds (Viano & Parenteau, 2010). However, part-time belt users may be willing to tolerate visual and auditory signals from a seat belt reminder system when traveling on short trips unbelted, thereby limiting the efficacy of this technology. ...
Introduction
Seat belts reduce the risk of fatal injury in a crash, yet in 2015, nearly 10,000 people killed in passenger vehicles were unrestrained. Enhanced seat belt reminders increase belt use, but a gearshift interlock that prevents the vehicle from being placed into gear unless the seat belt is used may prove more effective.
Method
Thirty-two people with a recent seat belt citation and who admitted to not always using a seat belt as a driver were recruited as part-time belt users and asked to evaluate two new vehicles. Sixteen drove two vehicles with an enhanced reminder for one week each, and 16 drove a vehicle with an enhanced reminder for one week and a vehicle with a gearshift interlock the following week. Sixteen full-time belt users who reported always using a seat belt drove a vehicle with a gearshift interlock for one week to evaluate acceptance.
Results
Relative to the enhanced reminder, the gearshift interlock significantly increased the likelihood that a part-time belt user used a belt during travel time in a trip by 21%, and increased the rate of belt use by 16%; this effect approached significance. Although every full-time belt user experienced the gearshift interlock, their acceptance of the technology reported in a post-study survey was fairly positive and not significantly different from part-time belt users. Six part-time belt users circumvented the gearshift interlock by sitting on a seat belt, waiting for the system to deactivate, or unbuckling during travel.
Conclusion
The gearshift interlock increased the likelihood that part-time belt users buckled up and the rate of belt use during travel relative to the enhanced reminder but could be more effective if it prevented circumvention.
Practical applications
An estimated 718–942 lives could be saved annually if the belt use of unbuckled drivers and front passengers increased 16–21%.
... Cervical and lumbar radiculitisdespite being common clinical diagnoses with ICD-10 codesare not typically reported pathologies in studies pertaining to MVCs. Rather, much research has examined the influence of intrinsic and/or extrinsic factors on sustaining AIS-3 injuries [25][26][27][28][29]. The Abbreviated Injury Scale, however, is a threat to life scale, with a score of 3 indicating to a serious threat [30]. ...
Background
There are more than 5 million motor vehicle collisions annually in the United States, resulting in more than 2 million injured occupants. The most common types of collisions are head-on impacts, rear-ends, side-swipes, and t-bones, whilst the most common injury sites are the cervical and lumbar spine. The purpose of this retrospective record review was to examine the differences in frequency of cervical and lumbar pathology across and between these common collision types.
Methods
Nine-hundred and three patients were included in this analysis, 88 of whom described being in a head-on collision, 546 in a rear-end, 123 in a side-swipe, and 146 in a t-bone. Four diagnoses were examined, two each for the cervical and lumbar regions: disc derangement and radiculitis. Pearson’s Chi-squared contingency tables were used to test whether there were differences in clinical diagnosis frequencies across collision type, while Marascuilo’s post hoc multiple proportion comparisons were conducted to determine inter-group differences.
Results
There were significant differences across collision type for cervical disc derangement (p < 0.0001), cervical radiculitis (p < 0.00001), lumbar disc derangement (p = 0.0002) and lumbar radiculitis (p < 0.00001). There were also significant differences in pathology frequency between collision types.
Conclusions
Symptomatic cervical disc derangements were more common among patients who were involved in aside-swipe, whereas symptomatic lumbar disc derangements were more common among those in head-on or side-swipe collisions. Expanded controlled prospective studies are encouraged to better understand the mechanisms of injury and determine radiculitis tolerance limits.
Electronic supplementary material
The online version of this article (10.1186/s12891-017-1797-5) contains supplementary material, which is available to authorized users.
... The vast majority was above 30 mph and some above 40 mph. Frontal Crashes involving velocity changes in the 30 mph to 40 mph account for approximately 1.4% of all frontal crashes (Viano and Parenteau, 2010). ...
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.
... There is a high degree of variation in the sampling weights in the NASS-CDS, so concerns may arise when analyses with small subpopulations are conducted (26); 1 case with a large sampling weight may unduly influence the results. Even with 9 years of data, sample sizes are somewhat small, and standard errors can be large (27). Our small sample size precluded the ability to analyze groups other than whites, blacks, and Hispanics. ...
Prior studies on racial and ethnic disparities in survival after motor vehicle crashes have examined only population-based death rates or have been restricted to hospitalized patients. In the current study, we examined 3 components of crash survival by race/ethnicity: survival overall, survival to reach a hospital, and survival among those hospitalized. Nine years of data (from 2000 through 2008) from the National Automotive Sampling System Crashworthiness Data System were used to examine white non-Hispanic, black non-Hispanic, and Hispanic drivers aged ≥15 years with serious injuries (injury severity scores of ≥9). By using multivariable logistic regression, we found that a driver's race/ethnicity was not significantly associated with overall survival after being injured in a crash (for blacks, odds ratio (OR) = 0.69, 95% confidence interval (CI): 0.36, 1.32; for Hispanics, OR = 1.00, 95% CI: 0.59, 1.72), and blacks and Hispanics were equally likely to survive to be treated at a hospital compared with whites (for blacks, OR = 1.00, 95% CI: 0.52, 1.93; for Hispanics, OR = 1.13, 95% CI: 0.71, 1.79). However, among patients who were treated at a hospital, blacks were 50% less likely to survive 30 days compared with whites (OR = 0.50, 95% CI: 0.33, 0.76). The disparity in survival after serious traffic injuries among blacks appears to occur after hospitalization, not in prehospital survival. © 2013 © The Author 2013. Published by Oxford University Press on behalf of the Johns Hopkins Bloomberg School of Public Health. All rights reserved. For permissions, please e-mail: [email protected]
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... While head injuries are the most common injury for all restrained occupants regardless of age (Durbin et al 2003, Bohman et al 2011, Nance et al 2011 GarcíaEspaña et al 2008, Viano et al 2010, Yoganandan et al 2011) thoracic injuries are seen more frequently with increasing age (Koppel et al 2011, Bansal et al 2011, Stitzel et al 2010, Ruan et al 2003). Biomechanical studies have highlighted that the stiffness of the thorax increases with increasing age (Maltese et al, 2008) and radiological assessment of torso shape has documented differences with age (Gayzik et al 2008, Kent et al 2005, Comeau, 2010). ...
The objective of this research was to delineate age-based differences in specific thoracic injury diagnoses for seat belt restrained rear seat occupants and describe the associated injury causation in order to provide insight into how the load of the seat belt is transferred to occupants of various sizes. Using data from the Crash Investigation Research and Engineering Network (CIREN), 20 cases of rear seated, lap and shoulder belt restrained occupants with AIS2+ thoracic injuries in frontal crashes were reviewed. Seven were children and adolescents age 8-15 years, 5 were 16-24 years, 3 were 25-54 years, and 5 were 55+ years. Six of the seven 8-15 year olds sustained injuries to the lung in the form of pulmonary contusion or pneumothorax. Only three of the seven sustained a skeletal (sternum or rib) fracture; only one of these three involved multiple ribs bilaterally. In contrast, four of the five 16-24 year olds sustained at least one rib fracture - often multiple and bilateral. The adult cohort (25+ years) was involved in predominantly more minor crashes; however they all sustained complex rib fractures - seven of the eight involved multiple ribs, four of the eight were also bilateral. Belt compression - either from the shoulder belt or the lap belt - was identified as the primary cause of the thoracic injuries. Often, there was clear evidence of the location of belt loading from AIS 1 chest contusions or abrasions. These findings have implications for age-based thoracic injury criteria suggesting that that different metrics may be needed for different age groups.
Objectives:
Vehicle and occupant responses in 35 mph NCAP tests were determined for small-midsize passenger cars grouped around model year (MY) 1980, 1990, 2000, 2010 and 2020. A baseline was established with 1980 vehicles not designed for NCAP. The results of four decades of vehicles designed for NCAP were compared to the baseline. The study also determined the risk for serious injury (MAIS 3 + F) by vehicle model year (MY) using 1989-2015 NASS and 2017-2020 CISS. It explored safety trends in frontal crashes over 50 MYs of vehicles.
Methods:
The 1980 baseline group was established with 10 1979-1983 MY passenger cars weighing <1,500 kg. Four decades of vehicle crash tests from five manufacturers established trends in vehicle dynamics and dummy responses over four decades of vehicles designed for NCAP. Triaxial acceleration of the head and chest were reanalyzed for each test to have a consistent set of responses over five decades. The risk for serious injury (MAIS 3 + F) to the driver and front passenger was determined by vehicle MY using 1989-2015 NASS and 2017-2020 CISS with belted and unbelted drivers and right-front passengers. The data was sorted in four MY groups 1961-1989 MY, 1990-1999 MY, 2000-2009 MY and 2010 MY-2021 MY. The risk for MAIS 3 + F injury was determined with standard errors using weighted data.
Results:
The 1980 NCAP tests brought about changes in vehicle structures and occupant restraints by 1990; however, HIC15 and 3 ms chest acceleration have not changed much the past 20 years since the use of advanced airbags and seatbelts with pretensioner and load-limiters. For the driver, HIC15 dropped 40 ± 19% from the 1980 to 1990 NCAP tests and dropped further to 76 ± 32% in 2020. The percentage drops after 1990 were not statistically significant. The driver 3 ms chest acceleration dropped 18 ± 5% from 1980 to 1990 and plateaued with 22 ± 6% in 2020. For the front passenger, HIC15 dropped 68 ± 52% from the 1980 to 1990 NCAP tests and plateaued at 71 ± 49% in 2020. The passenger 3 ms chest acceleration dropped 13 ± 5% from 1980 to 1990 and has fluctuated with minimal change. Injury risks based on responses show the same initial drop in 1990 and have remained essentially constant. Nothing meaningful has changed in dummy responses in the past 20 years of NCAP testing. The field data found the belted driver MAIS 3 + F risk was 1.66 ± 0.37% in 1961-1989 MY vehicles and 1.39 ± 0.33% in 2010-2021 MY vehicles. For belted right-front passengers, the risk was 1.52 ± 0.39% in 1961-1989 MY vehicles and 1.42 ± 0.46% in 2010-2021 MY vehicles. The field data shows no meaningful change in injury risk in 50 MYs of vehicles. NCAP involves 35-40 mph delta-V, which represents a small fraction, 0.33%, of belted occupant exposure and only 8.6% of severe injury based on 1994-2015 NASS.
Conclusions:
The NCAP test lacks field relevance. Manufacturers are merely "tuning" the restraint systems for star ratings without meaningful changes in field injury risks the past 20 years. There are disbenefits of "tuning" safety for a single, high-severity crash when most of the severe injury occurs in lower severity crashes. NHTSA should reevaluate plans to change the dummy to Thor and add BrIC injury criteria to assess NCAP responses. These changes would cause manufacturers to further "tune" structures, restraints and interiors without meaningful effects in real-world crashes.
Objective:
The history of airbags was reviewed for benefits and risks as they became a supplement to lap-shoulder belts. Sled and crash tests were evaluated and field data was analyzed for airbag effectiveness. Field data on airbag deaths and studies on mechanisms of deployment injury were analyzed. The history was reviewed as airbags evolved from the early 1970s to today.
Methods:
Airbag benefits were determined from NHTSA crash tests with unbelted and belted dummies in 40, 48, and 56 km/h (25, 30, and 35 mph) frontal impacts with and without airbags. The literature was reviewed for testing of passive restraints with and without airbags. Recent NCAP tests were compared with earlier tests to determine the change in occupant responses with seatbelts and supplemental airbags in modern vehicles. 1994-2015 NASS-CDS field data was analyzed for MAIS 4 + F injury. Risks were compared for belted and unbelted occupants in frontal impacts by delta V. Airbag risks were identified from field deployments and research. The 1973-76 GM fleet had two deaths due to the occupant being out-of-position (OOP). The mechanisms of injury were determined. From 1989-2003, NHTSA investigated 93 driver, 184 child passenger, and 13 adult passenger airbag deaths. The data was reviewed for injury mechanisms. Second generation airbags essentially eliminated OOP airbag deaths. More recently, three suppliers were linked to airbag rupture deaths. The circumstances for ruptures were reviewed.
Results:
The risk for serious head injury was 5.495% in drivers and 4.435% passengers in 40-48 km/h (25-30 mph) frontal crash tests without belts or airbags. It was 80.5% lower at 1.073% in drivers and 82.0% at 0.797% in passengers with belts and airbags in 35 mph NCAP crash tests of 2012-20 MY vehicles. NASS-CDS field data showed a 15.45% risk for severe injury (MAIS 4 + F) to unbelted occupants and 4.68% with belted occupants in 30-35 mph frontal crash delta V with airbags, as deployed. The reduction in risk was 69.7% with belt use and airbags deploying in 96.1% of crashes. There were benefits over the range of delta V. Two airbag deaths were studied from the 1970s GM fleet of airbags. The unbelted driver death was caused by punchout force with the airbag cover blocked by the occupant and membrane forces as the airbag wrapped around the head, neck or chest with the occupant close to the inflating airbag. The unbelted child death was from airbag inflation forces from pre-impact braking causing the child to slide forward into the deploying airbag. Research showed that unrestrained children may have 13 different positions near the passenger airbag at deployment. NHTSA investigation of first generation airbag deaths found most driver deaths were females (75.3%) sitting forward on the seat track, close to the driver airbag. Seatbelt use was only 30%. Most child deaths (138, 75.4%) involved no or improper use of the lap-shoulder belts. Of these, 115 deaths involved pre-impact braking. Only 37 (20.2%) children were in child seats with 29 in rear-facing and 8 in forward-facing child seats. Eight child deaths (4.4%) occurred with lap-shoulder belt use. Airbag designs changed. More recently, Takata airbags were related to at least 24 deaths by airbag rupture prompting a recall; the successor company Joyson had an airbag recall. ARC airbags have experienced a chunk of the inflator propelled into the driver during deployment with several deaths leading to a recall.
Conclusions:
Airbags are effective in preventing death and injury in crashes. They provide the greatest protection in combination with seatbelt use. NHTSA estimated airbags saved 28,244 lives through 1-1-09 while causing at least 320 deployment deaths, which has prompted improved designs, testing, and recalls.
The current study aimed to develop a method for estimating whole-body Injury metric values (WBIMs), which are widely used in epidemiological studies, to determine airbag deployment threshold during frontal crashes using a computational human surrogate model and real-world crash data. To this end, a finite element human body model was instrumented to predict the risk of the injuries. The whole body was divided into 22 body regions. Then, body region-specific injury pattern databases were constructed for these body regions using the NASS-CDS database. Monte Carlo Sampling was performed to calculate WBIMs, such as the probability of death and lost years of life. A series of frontal crash simulations was performed for various Delta-V with and without deploying pyrotechnic restraint systems. Lastly, the WBIM values obtained from the proposed method were compared to those obtained from the NASS-CDS. From the Delta-V of 25 km/h, the airbag-deployed conditions demonstrated a protective effect compared to the non-deployed conditions. The predicted WBIM values using the proposed method demonstrated a similar trend to that presented in the field data. The proposed method to estimate WBIM values can be used to evaluate various occupant protection systems.
div class="section abstract"> The risk for severe injury (MAIS 4+F) was determined by crash type, seatbelt use and crash severity (delta V) using 22 years of NASS-CDS from 1994-2015 with all light vehicles and occupants 15+ years old. There were 9 increments of delta V from <16-72+ km/h (<10-45+ mph). Crashes were grouped by the location of damage to the front, near-side, far-side and rear. Injury risk was calculated by dividing the number of severely injured (MAIS 4+F) by the number of exposure (MAIS 0+F) occupants using weighted data. Standard errors were determined. The data and plots provide a national estimate of injury by delta V in front, near-side, far-side and rear impacts based on the multi-year field data in NASS-CDS.
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Hanoi City is a typical motorcycle dominant city in Vietnam with a modal share of motorcycles of more than 80% and motorcycle riders involved in more than 70% of road fatalities. It is important to understand the major causes of motorcycle crash severity to suggest effective countermeasures. There have been studies elsewhere examining factors related to small-displacement motorcycle crash severity, but work in Vietnam is scarce. This study uses ordinal logistic regression to investigate contributory factors to the odds of severe crashes involving motorcycle riders. A distinction is made between crashes where motorcyclists are involved as the second party (i.e., as victims of the crash) on the one hand and as the first party (i.e., as the person responsible for causing the crash) on the other hand. Results show that age and gender of the first party person, size of the vehicle collided with, and presence of a pillion passenger significantly contribute to the severity of crashes in which motorcyclists are involved as the second party. Significant factors to the severity of crashes in which motorcyclists are involved as the first party are age, time of the crash, road class, size of the second party vehicle, pillion passenger presence, and riding speed. The findings contribute to a deeper understanding of fatal crashes with small-displacement motorcycles in a developing city. This study helps to identify countermeasures to improve road safety of small-displacement motorcycle riders.
Most of the previous studies that investigated the factors increasing the severity of rear-end collisions were based on analyzing collision reports from multiple years and combining them into a single dataset for analysis. Analyzing pooled data from multiple years carries the risk of introducing aggregation bias in the analysis. Those aggregated models might be structurally unstable, and the significance of the risk factors identified using those aggregated models might change over time due to the ongoing changes in vehicle technologies, law-enforcement technologies, and drivers’ attitudes. This study demonstrates the importance of testing the temporal stability of pooled data by utilizing logistic regression modeling to analyze all rear-end collisions that occurred in North Carolina for the period from January 1, 2004 to December 31, 2015. Separate models were developed for each year to model injury severity of striking and struck drivers. The year-wise models were compared together to identify the most temporally stable factors, and it was found that older and female drivers are usually more severely injured, but they do not increase injury severity of the drivers they collide with. It was also found that compared to other light-duty vehicles, passenger cars are usually associated with increased injury severity to their drivers and reduced injury severity to the drivers of the vehicles they collide with. The increased age of a vehicle was found to increase the injury severity of its driver as well as the driver of the vehicle it collides with. Dark conditions were found to increase drivers’ injury severity, but adverse weather conditions have no similar effect. For comparison, aggregated models were also developed by pooling data from all analysis years (from 2004 to 2015) and were found to return significant factors that were found by the year-wise models to be temporally unstable. Chow tests were performed on the data, and it was found that pooling data for four years or more generally returned structurally unstable models.
Purpose: This is a descriptive study of the incidence and risk for severe injury in a single impact and multi-impact crashes by belt use and crash type using NASS-CDS.
Methods: 1997–2015 NASS-CDS was used to determine the distribution of crashes by the number of impacts and severe injury (MAIS 4+F) to >15 year old non-ejected drivers by seatbelt use in 1997+ MY vehicles. It compares the risk for severe injury in a single impact and in crashes involving two, three or four+ impacts in the collision with focus on a frontal crash followed by other impacts.
Results: Most vehicle crashes involve a single impact (75.4% of 44,889,518 vehicles), followed by two impact crashes (19.6%), three impact crashes (5.0%) and four+ impacts (2.6%). For lap-shoulder belted drivers, the distribution of severe injury was 42.1% in a single impact, 29.3% in two impacts, 13.4% in three impacts and 15.1% in 4+ impact crashes. The risk for a belted driver was 0.256% ± 0.031% in a single impact, 0.564% ± 0.079% in two impacts, 0.880% ± 0.125% in three impacts and 2.121% ± 0.646% in four+ impact crashes. The increase in risk from a single crash to multi-impact collisions was statistically significant (p < 0.001).
In a single impact, 53.8% of belted drivers were in a frontal, 22.4% in a side, 20% in a rear crash and 1.7% in a rollover. The risk for severe injury was highest in a rollover at 0.677% ± 0.250%, then a near-side impact at 0.467% ± 0.084% and a far-side impact at 0.237% ± 0.071%. Seatbelt use was 82.4% effective in preventing severe injury (MAIS 4+F) in a rollover, 47.9% in a near-side impact and 74.8% in a far-side impact.
In two impact crashes with a belted driver, the most common sequence was a rear impact followed by a frontal crash at 1,843,506 (21.5%) with a risk for severe injury of 0.100% ± 0.058%. The second most common was a frontal impact followed by another frontal crash at 1,257,264 (14.7%) with a risk of 0.401% ± 0.057%. The risk was 0.658% ± 0.271% in a frontal impact followed by a rear impact. A near-side impact followed by a rear crash had the highest risk for severe injury at 2.073% ± 1.322%.
Conclusions: Restraint systems are generally developed for a single crash or sled test. The risk for severe injury was significantly higher in two, three and four+ impact crashes than a single impact. The majority (57.9%) of severe injury occurred in multi-impact crashes with belted drivers. The evaluation of restraint performance warrants additional study in multi-impact crashes.
Occupant motion and injury response in motor vehicle crashes is dictated by the forces applied to the human body in combination with the relative motion between occupant and vehicle. These responses are complex and dependent on many factors including those relating to crash, vehicle, and occupant characteristics. The study of occupant response is an important step in improving vehicle design and crashworthiness. This chapter provides an overview of the important aspects of occupant response for the four main crash modes: frontal, side, rollover, and rear. The general characteristics of occupant kinematic response are discussed with respect to each crash mode. Typical injury patterns and mechanisms are identified and their relationship to occupant motion and interaction with the crash environment is highlighted.
This study examines the potential for evidence-based solutions to reduce the burden of non-intentional farm injury fatalities in Australia and identifies key priority interventions for action. Data from the National Coroner's Information System indicate that there were 326 non-intentional farm injury deaths in the period 2003-2006. Of these, the six leading agents, which were selected for further review, were responsible for 559f (n = 181) of all cases. Based on existing evidence, a list of potentially effective solutions to these common agents (tractors, quad bikes, dams/water bodies, farm utilities, motorcycles and horses) was defined. Each selected case was reviewed to ascertain if the relevant intervention may have been effective by either preventing the incident and/or the fatality. A conservative approach was adopted to ensure that only cases where adequate information was available in the database were categorised.
Purpose:
This is a descriptive study of the annual incidence of brain injuries in motor vehicle crashes by type, seat belt use, and crash severity (delta V) using national accident data. The risk for concussion, diffuse axonal injury (DAI), and severe head injury was determined.
Methods:
1994-2011 NASS-CDS was analyzed to estimate the number of brain injuries annually in nonejected adults involved in motor vehicle crashes. Crashes were grouped by front, side, rear, and rollover, and the effect of belt use was investigated. Light vehicles were included with model year 1994+. Head injuries were identified as concussion, DAI, severe head injury (Abbreviated Injury Scale [AIS] 4+), and skull fracture. The annual incidence, risk, and rate for different types of head injury were estimated with standard errors.
Results:
Motor vehicle crashes involved 33,191 ± 7,815 occupants with concussion, 5,665 ± 996 with AIS 4+ head injuries, 986 ± 446 with DAI, and 3,300 ± 531 with skull fracture annually. The risk was 1.64 ± 0.39% for concussion, 0.28 ± 0.05% for severe head injury (AIS 4+), 0.05 ± 0.02% for DAI, and 0.16 ± 0.03% for skull fracture in tow-away crashes. The risk for severe head injury (AIS 4+) was highest in rollovers (0.74 ± 0.16%) and lowest in rear impacts (0.17 ± 0.05%). Head injury risk depended on seat belt use, crash type, and crash severity (delta V). Seat belt use lowered the risk for AIS 4+ head injury by 74.8% and skull fracture by 73.2%.
Conclusions:
Concussions occur in about one out of 61 occupants in tow-away crashes. The risk was highest in rollover crashes (4.73 ± 1.09%) and it was reduced 69.2% by seat belt use. Severe brain injuries occurred less often and the risk was also reduced by seat belt use.
Purpose:
NHTSA studied interior loose objects in the 2000-04 NASS-CDS as part of rulemaking on cargo retention testing in FMVSS 208. This study extends the investigation of cargo and loose interior object loading on occupant injury and seat deformation by cargo in motor-vehicles crashes using NASS-CDS data.
Methods:
1996-2011 NASS-CDS was used to investigate the effects of loose interior objects and seat responses on occupant injury in motor vehicle crashes. Crashes were grouped by front, side, rear and rollover. Light vehicles were included with model year 1994+. NASS-CDS added new variables for cargo loading as an injury source and cause for seat deformation in 2007. NASS-CDS electronic cases were analyzed for rear occupants with moderate to severe injury (AIS 2+) from loose objects and MAIS 4+F injury with cargo deforming seats in frontal crashes.
Results:
There were no AIS 2+ injuries due to cargo loading in the 16 years of NASS-CDS, including specific coding from 2007-11 and by case evaluation in earlier years. In frontal crashes, loose or other interior objects accounted for 250 AIS 2+ injuries in drivers, 32 in front passengers and 206 in 2nd row occupants. The overall rate of AIS 2+ injury was 1.000% for 2nd row occupants due to loose or other interior objects. The individual cases of AIS 2+ injury from loose or other interior objects in 2nd row occupants involved 16 occupants with 44 injuries in frontal crashes. Two cases involved police vehicles and one, an ambulance. In two other cases, the loose interior object was a bike placed in the 3rd row of a station wagon and an unsecured fan in the 2nd row. Each year, there were 540 driver seats deformed by cargo, 438 front-passenger seats and 889 in 2nd row seats. Most cargo deformation of front seats occurred in frontal crashes. Annually, there were 462 driver seats deformed by cargo in frontal crashes, 143 front-passenger seats and 660 in 2nd row seats.
Conclusions:
This analysis supports NHTSA's earlier conclusion that cargo is not a major source of injury in frontal crashes. While anecdotal cases have been presented in the literature, there were no cases in NASS-CDS. NASS-CDS also showed that when untethered cargo deforms rear seats, it was not related to severe injury to 2nd row occupants.
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.
To assess the efficacy of occupant protection systems, the authors measured the mortality reduction associated with air bag deployment and seat belt use for drivers involved in head-on passenger car collisions in the United States. They used a matched case-control design of all head-on collisions involving two passenger cars reported to the Fatality Analysis Reporting System in 1992-1997, and driver mortality differences between the paired crash vehicles for air bag deployment and seat belt use were measured with matched-pair odds ratios. Conditional logistic regression was used to adjust for multiple effects. There were 9,859 head-on collisions involving 19,718 passenger cars and drivers. Air bag deployment reduced mortality 63% (crude odds ratio (OR) = 0.37, 95% confidence interval (Cl): 0.32, 0.42), while lap-shoulder belt use reduced mortality 72% (OR = 0.28, 95% Cl: 0.25, 0.31). In a conditional logistic model that adjusted for vehicle (rollover, weight, age) and driver (age, sex) factors, air bags (OR = 0.71, 95% Cl: 0.58, 0.87) and any combination of seat belts (OR = 0.25, 95% Cl: 0.22, 0.29) were both associated with reduced mortality. Combined air bag and seat belt use reduced mortality by more than 80% (OR = 0.18, 95% Cl: 0.13, 0.25). Thus, this study confirms the independent effect of air bags and seat belts in reducing mortality. Am J Epidemiol 2001;153:219-24.
In the mid-1990s, evidence emerged that air bag deployments could result in deaths to vulnerable vehicle occupants who were very close to air bag modules when they deployed. In 1997, federal frontal crash test requirements were modified to allow crash testing with unbelted dummies to be performed using sled tests. As a result, vehicle manufacturers were able to redesign air bags to deploy with less force and energy, thereby reducing the toll of air bag-induced deaths. However, there was concern that depowered air bags may not provide the same level of protection to unbelted occupants in severe frontal crashes, particularly occupants of large stature and body mass. This paper provides a summary of recent studies addressing this issue.
To expedite the accrual of data regarding air bag performance, the collection of additional crash data was funded by the Alliance of Automobile Manufacturers. A panel of experts was commissioned to oversee the process and evaluate the data. During the past 6 years, a series of studies has been undertaken by panel members and others to evaluate the performance of redesigned air bags and the data are summarized here.
There is now convincing evidence that the combination of air bag redesign and public education have resulted in dramatic reductions in air bag-induced infant and child deaths. In addition, the frontal crash fatality risks among children sitting in front seats have been reduced by as much as half, with younger children showing the greatest benefits. Among adult drivers and right-front passengers, there is no evidence for the predicted overall loss of protection with sled-certified air bags and there are far fewer air bag-induced deaths among this population. However, despite exhaustive analyses of frontal-crash data, the possibility of a somewhat elevated fatality risk among a subset of unbelted drivers in sled-certified 1998-1999 model vehicles cannot be ruled out. There also is some evidence that the risks of serious chest injury may be higher among unbelted drivers in frontal crashes in sled-certified vehicles with redesigned air bags. Further research is warranted to determine whether these differences remain in newer model vehicles designed to the advanced air bag rule, which took effect in 2003.
The effectiveness of air bags was estimated in this study by comparing driver fatalities in frontal crashes with driver fatalities in nonfrontal crashes, for cars with air bags and manual belts and cars with manual belts only.
Fatal Accident Reporting System data for drivers fatally injured during 1985 to 1991 in 1985 to 1991 model year cars that were equipped with air bags in or before model year 1991 were analyzed.
Driver fatalities in frontal crashes in air bag cars were 28% lower than those in comparable cars with manual belts only. This percentage was used for estimating the overall fatality reduction in air bag cars. The reduction was greater in large cars (50%) than in midsize cars (19%) or in small cars (14%). Air bags reduced driver fatalities in frontal crashes involving ejection by about 9%. Fatalities in frontal crashes among drivers who were reportedly using manual belts at the time of the crash were reduced by about 15%. The comparable reduction among drivers who were reportedly not using manual belts was 31%.
It was estimated that air bags reduced the total number of all driver fatalities by about 19%.
Airbags have been shown to significantly reduce mortality and morbidity in motor vehicle crashes. However, the airbag, like the seat belt, produces its own range of injuries. With the increasing use of airbags in the UK, airbag associated injuries will be seen more often. These are usually minor, but in certain circumstances severe and fatal injuries result. Such injuries have been described before in the medical literature, but hitherto most reports have been from North America. This is the first case report from the UK of serious injury due to airbag deployment and describes the case of a driver who was fatally injured when her airbag deployed in a moderate impact frontal collision where such severe injury would not normally have been anticipated. The range of airbag associated injuries is described and predisposing factors such as lack of seat belt usage, short stature, and proximity to airbag housing are discussed. The particular dangers airbags pose to children are also discussed.
The purpose of this study was to evaluate the effectiveness of frontal restraint systems in reducing the potential for head injuries, specifically brain injuries and skull fractures. The US DOT NASS database files from 1991-1998 were evaluated for drivers and right front seat occupants in frontal crashes. Of the total driver and right front seat occupants in this data set, 3.83% sustained a brain injury without skull fracture, 0.05% sustained a skull fracture without a brain injury, and 0.16% sustained both brain injury and skull fracture. The incidence of head injury was lowest among occupants who were restrained by belt alone (2.76%) and by both airbag and belt systems (3.51%). The unrestrained population had a 10.39% incidence of at least one type of head injury. In general, for maximum AIS > or = 2 head injuries, airbag effectiveness was greatest between 16-45 kph crash delta V. For the more severe maximum AIS > or = 3 head injuries, the airbag restraint had its greatest effect up to 35 kph. It can be concluded that brain injury in frontal crashes is substantially reduced with the presence of a restraint system and the use of both airbag and belt restraint offers the greatest protection across all delta V categories. Restraint system effectiveness for the non-head-injured occupant is variable but, generally, the belted occupant sustained the lowest percentage of injuries. Skull fractures in frontal impact were relatively rare and the incidence appeared to be unaffected by the presence of a restraint system.
A woman who was the lap/shoulder belt-restrained driver of a car equipped with a full-size air bag was involved in an oblique frontal collision with a tractor-trailer combination. She was extremely out of position, i.e., witnessed to be slumped over the steering wheel before impact. This preimpact positioning led to fatal injuries resulting from the inflating air bag. Postmortem examination showed an unusual partial ring fracture of the base of the skull, which to the authors' knowledge has not previously been reported.
In motor vehicle collisions the mechanism of injury is important in determining severity as well as for triage decisions in the pre-hospital phase of patient management. This study correlates deformation of the basic structures of the passenger compartment [windscreen, control panel (dashboard) and steering wheel] with occupants' injuries in passenger vehicle head-on collisions involving non-airbag-carrying vehicles, with or without compartment intrusion. The study took place in the broad urban area of Patras, over an 18-month period (January 2000-June 2001) and evaluated 48 vehicle crashes. Car and compartment deformation are significant factors affecting occupants' injuries and consequently the appropriate type of further treatment, either in the hospital setting or primary health-care centres. It would be particularly useful to transmit the post-crash condition of a vehicle to the trauma dispatch centre, utilising satellite technology, thus allowing the centre to organise the rescue teams, plan triage in advance and provide the emergency medical personnel with all necessary information before their arrival at the scene of the accident.
This study compares injury outcomes in vehicle crashes involving different age groups of belted passengers. Two datasets were considered. Firstly, UK national data revealed that younger passengers are much more likely to be involved in crashes per million miles travelled compared to older passengers although older passengers are much more likely to be killed or seriously injured compared to younger passengers. Secondly, in-depth vehicle crash injury data were examined to determine some of the underlying reasons for the enhanced injury risk amongst older passengers. In crashes of approximately equal severity, the older passenger group were significantly more likely to be fatally injured in frontal crashes (p<0.001). However young passengers were as equally likely to be killed in struck-side crashes compared to the older group. The results also showed that older passengers sustained more serious injuries to the chest region in frontal crashes compared with the younger aged group (p<0.0001) and it is this body region that is particularly problematic. When the data were analysed further, it was found that a large proportion of passengers were female and that in the majority of cases, the seat belt was responsible for injury. Since by the year 2030, 1 in 4 persons will be aged over 65 in most OECD countries, the results suggest a need for intervention through vehicle design including in-vehicle crashworthiness systems that take into account reduced tolerance to impact with ageing.
Obesity rates are reaching an epidemic worldwide. In the US, nearly 40 million people are obese. The automotive safety community is starting to question the impact of obesity on occupant protection. This study investigates fatality and serious injury risks for front-seat occupants by Body Mass Index (BMI). NASS-CDS data was analyzed for calendar years 1993-2004. Occupant exposure and injury was divided in seven BMI categories with obese defined as those with BMI ≥ 30 kg/m2. Injuries were studied for drivers and right-front passengers and included analysis of lap-shoulder belted and unbelted occupants. The results show that obese occupants have a higher fatality risk compared to normal BMI occupants; morbidly obese occupants (BMI ≥ 40 kg/m2) have 2.25 times higher fatality risk (1.15% v 0.51%). The fatality risk for belted obese drivers was 0.29%, which was 6.7 times lower than the 1.94% for those unbelted. These rates are similar to other BMI occupants. In conclusion, obesity influences the risk of serious and fatal injury in motor vehicle crashes. The greatest difference in risk is for fatalities, which are highest in the morbidly obese, in part, because of lower seatbelt wearing rates.
Objective
To estimate the association of driver air bag presence with driver fatality in road traffic crashes.
Design
Matched pair cohort study.
Setting
All passenger vehicle crashes in the United States during 1990-2000 inclusive.
Subjects
51 031 driver-passenger pairs in the same vehicle.
Main outcome measures
Relative risk of death within 30 days of a crash.
Results
Drivers with an air bag were less likely to die than drivers without an air bag (adjusted relative risk 0.92 (95% confidence interval 0.88 to 0.96)). This estimate was nearly the same whether drivers wore a seat belt (adjusted relative risk 0.93) or not (0.91). Air bags were associated with more protection for women (0.88 (0.82 to 0.93)), than for men (0.94 (0.90 to 0.99)). Drivers wearing a seat belt were less likely to die than unbelted drivers (0.35 (0.33 to 0.36)). Belted drivers with an air bag were less likely to die than unbelted drivers without an air bag (0.32 (0.30 to 0.34)).
Conclusions
If the associations are causal the average risk of driver death was reduced 8% (95% confidence interval 4% to 12%) by an air bag. Benefit was similar for belted and unbelted drivers and was slightly greater for women. However, seat belts offered much more protection than air bags.
What is already known on this topic
What is already known on this topic
Studies have estimated that driver air bags reduce the risk of death in a road vehicle crash by 10-14% These studies disagree as to whether benefit is greater for drivers wearing a seat belt or for unbelted drivers
What this study adds
What this study adds
Having an air bag was associated with an 8% reduction in the risk of death, whether the driver was belted or not The reduction in risk was greater for women (12%) than for men (6%)
Seat belts provided much greater protection, with seat belt use reducing the risk of death by 65% (or by 68% in combination with an air bag)
Airbags have been shown to significantly reduce mortality and morbidity in motor vehicle crashes. However, the airbag, like the seat belt, produces its own range of injuries. With the increasing use of airbags in the UK, airbag associated injuries will be seen more often. These are usually minor, but in certain circumstances severe and fatal injuries result. Such injuries have been described before in the medical literature, but hitherto most reports have been from North America. This is the first case report from the UK of serious injury due to airbag deployment and describes the case of a driver who was fatally injured when her airbag deployed in a moderate impact frontal collision where such severe injury would not normally have been anticipated. The range of airbag associated injuries is described and predisposing factors such as lack of seat belt usage, short stature, and proximity to airbag housing are discussed. The particular dangers airbags pose to children are also discussed.
Automotive airbag technology has reduced the number of injuries and fatalities resulting from motor vehicle crashes. With the increasingly frequent application of this safety feature in automobiles, recent reports of airbag-associated injuries have emerged, including ocular and non-lethal cardiac trauma. We report three cases of airbag-related upper extremity injuries seen at a level-I trauma center over a 6-month period. A heightened awareness of this type of injury in patients injured in motor vehicle crashes with airbag deployment is recommended. The awareness, identification, and management of these high energy injuries will take on added meaning as the airbag technology becomes universally applied.
Objective and Design: To determine the relationship between airbags and lower extremity injuries, 10 drivers admitted to a level-I trauma center with substantial lower extremity trauma incurred in crashes involving airbag-equipped vehicles were studied in depth with regard to their injuries, the circumstances of the crashes, and the medical charges for the acute management of those injuries. Materials and Methods: During the clinical investigation portion of this study, we photographed lower extremity injuries, both soft tissue and radiographs, and performed a detailed surgical exploration during the debridement of open wounds or fracture fixation to treat them appropriately and to define the mechanism of injury, the fracture pattern, the pattern of soft-tissue insult, and the extent of periosteal stripping. We recorded the hospital and professional charges associated with the acute management not only of these injuries, but of the other injuries as well. The analysis performed for each case included a detailed crash reconstruction, including force, contact point, and vehicle intrusion data. Particular attention was paid to the dashboard and toe pan areas to determine deformation and intrusion and their association with thigh, leg, and foot injuries. Pertinent deformation and trajectory information was entered into the Calspan Reconstruction of Accident Speeds on the Highway (CRASH) computer program to generate a triangle V or change in velocity measurement used as a measure of collision severity. When field data were incompatible with the limitations of the CRASH program, manual calculations such as "slide to stop'' and conservation of momentum formulas were used. Results: The seven male and three female drivers had a mean age of 39.4 years. Only four used seatbelt restraints. The mean triangle V was 28.3 mph and the mean maximum crush was 32.4 inches. The mean Injury Severity Score of 13.2. Musculoskeletal injuries included 11 foot/ankle fractures, 6 tibial fractures, 2 patellar fractures, 6 femoral fractures, and two acetabular/pelvic fractures. Other trauma included abdominal, thoracic, and facial injuries. All drivers survived. The mean total acute care cost was $54,578. Conclusions: Although airbags have been shown to reduce head and upper torso injuries, it seems that these safety devices do not prevent injuries to the lower extremity.
This paper presents the dynamic injury tolerances for the female humerus and forearm derived from dynamic 3-point bending tests using 22 female cadaver upper extremities. Twelve female humeri were tested at an average strain rate of 3.7±1.3%/s. The strain rates were chosen to be representative of those observed during upper extremity interaction with frontal and side airbags. The average moment to failure when mass scaled for the 5th centile female was 128±19 Nm. Using data from the in situ strain gauges during the drop tests and geometric properties obtained from pretest CT scans, an average dynamic elastic modulus for the female humerus was found to be 24.4±3.9 GPa. The injury tolerance for the forearm was determined from 10 female forearms tested at an average strain rate of 3.94±2.0%/s. Using 3 matched forearm pairs, it was determined that the forearm is 21% stronger in the supinated position (92±5 Nm) versus the pronated position (75±7 Nm). Two distinct fracture patterns were seen for the pronated and supinated groups. In the supinated position the average difference in fracture time between the radius and ulna was a negligible 0.4±0.3 ms. However, the pronated tests yielded an average difference in fracture time of 3.6±1.2 ms, with the ulna breaking before the radius in every test. This trend implies that in the pronated position, the ulna and radius are loaded independently, while in the supinated position the ulna and radius are loaded together as a combined structure. To produce a conservative injury criterion, a total of 7 female forearms were tested in the pronated position, which resulted in the forearm injury criterion of 58±12 Nm when scaled for the 5th centile female. It is anticipated that these data will provide injury reference values for the female forearm during driver air bag loading, and the female humerus during side air bag loading.
This study investigated the risk of severe-to-fatal injury (MAIS 4+F) to near- and far-seated front occupants in side impacts by belt use and crash severity (delta V).
1993-2007 NASS-CDS was analyzed for front-seat occupants in side impacts while they were either the near-side or far-side occupant by belt use. Light vehicles were included with model year 1994+. Injury severity was subdivided into MAIS 0-2, 3, and 4+F. The risk for MAIS 4+F injury was determined by dividing the number of MAIS 4+F by the number of exposed occupants with known injuries. Individual NASS-CDS cases were downloaded from the 1997-2007 electronic data to evaluate injury patterns causing high relative risks.
In 35+ mph side-impact delta Vs, the risk for MAIS 4+F injury was 75.4 +/- 41.0% for unbelted near-side and 48.1 +/- 14.6% for unbelted far-side occupants. The risk was 51.8 +/- 14.8% for belted near-side and 30.9 +/- 8.2% for far-side occupants. Seat belt use was 81.4% effective in preventing MAIS 4+F injury for near-side occupants and 93.5% for far-side occupants. The relative risk (RR) for unbelted compared to belted occupants was 35.9 for far-side occupants in 10-15 mph delta V crashes. The relative risk was 35.1 for near-side occupants in < 10 mph delta V side impacts. The high relative risks were associated with complex, high-speed multi-collision crashes often with occupant impacts on the windshield, steering wheel, or other frontal components and ejection.
Seat belt use was more effective in preventing severe injury (MAIS 4+F) to far-side occupants than near-side occupants in < 25 mph delta V impacts. High relative risk for unbelted occupants in low-speed side impacts was explained by the fact that the accidents were high-speed, multi-impact collisions. Severe injury was caused by ejection, impact with the side interior, or impact with the frontal components where airbags sometimes deployed.
This is a conference paper. Much analysis of accident data and most crash tests focus on single impacts. However, in reality, multiple impacts account for a large proportion of serious injury accidents and are expected to become a larger proportion as countermeasures, developed primarily for single mode impacts, take effect. It is proposed that multiple impacts should be considered separately since consideration of their characteristics may have implications for occupant protection. This study investigates multiple impacts in more detail and, in particular, explores their relative importance in the accident population, analyses their characteristics and discusses some possible consequences for occupant protection measures.
Previous studies had demonstrated that injury severity and risk of death after motor-vehicle crashes are related to human body characteristics. The purpose of this study was to clarify the relationship between body mass index (BMI) and head injury severity in front seat passengers after a frontal collision.
Data from all front seat occupants with at least one injury, older than 16 years old involved in a frontal collision from 1993 to 2005 were retrieved from the National Automotive Sampling System (NASS) database. Patient and collision characteristics were analyzed. Two cohorts were defined according to BMI < or > or =30 kg/m2.
A total of 6,977 patients were included in this study, 5,918 (85%) had complete data on weight and height. Patient's mean age was 37 +/- 18 years old, the median ISS was 6, interquartile range (IQR) 15, and 61% were men. The mortality rate was positively associated to the crash delta velocity (DV) (p < 0.0001). The use of restraint system reduced the risk of death (p = 0.01). There was a significant increase in fatal outcome (p < 0.0001; RR 1.84 95% CI 1.61-2.1) and injury severity (ISS >25 p < 0.0001; RR 1.36 95% CI 1.19-1.54) in the obese cohort. Obese patients had higher chances of having a maximum head injury (Abbreviated Injury Score head = 6) than those not obese (p = 0.003; RR 1.97 95% CI 1.52-2.55).
Obese passengers are more likely to suffer a more severe head trauma after a frontal collision. Further studies with computational models are needed to determine the precise role of BMI on brain injury-related biomechanical metrics.
The objectives of this study were to examine the response, repeatability, and injury predictive ability of the Hybrid III small-female dummy to static out-of-position (OOP) deployments using a depowered driver-side airbag. Five dummy tests were conducted in two OOP configurations by two different laboratories. The OOP configurations were nose-on-rim (NOR) and chest-on-bag (COB). Four cadaver tests were conducted using unembalmed small-female cadavers and the same airbags used in the dummy tests under similar OOP conditions. One cadaver test was designed to increase airbag loading of the face and neck (a forehead-on-rim, or FOR test). Comparison between the dummy tests of Lab 1 and of Lab 2 indicated the test conditions and results were repeatable. In the cadaver tests no skull fractures or neck injuries occurred. However, all four cadavers had multiple rib fractures. These results suggested that an older, osteoporatic, small-female driver would experience AIS > or = 3 thoracic injury if exposed to this type of depowered airbag inflation for the three positions tested, but would be unlikely to experience any head or neck injury. The cadaver results provided no information about the possibility of AIS > or = 3 rib fractures for the average small, female driver. The Hybrid III small-female dummy results suggest that a low percentage (15%) of small, female drivers would experience AIS > or = 3 thoracic injuries if they had their chest on the module cover at the time of deployment of this depowered airbag. Also, for this position, the dummy results indicated a risk of an AIS = 2 neck injury for some small, female drivers. For all positions tested, the dummy results predicted that head injury was unlikely for most small-female drivers.
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.
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 >or=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.
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.
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'').
More than half of all brain trauma is caused by motor vehicle crashes. Prevention strategies that reduce the likelihood of motor vehicle crashes or injuries to occupants will also prevent trauma. Many effective strategies have yet to be applied on a large scale. Roadway design improvements such as removal of fixed objects from roadsides, widening roadside recovery zones, installing dividers between opposing lanes of traffic, and replacing fixed utility poles with breakaway designs, have been effective in reducing crashes and injuries. Driver measures of documented benefit include the 55 mph speed limit, safety belt use laws, 21 year legal drinking age, administrative license suspension for drinking drivers, and driving curfews and postponement of licensure for teenagers. Motor vehicle safety has improved greatly since the National Highway Traffic Safety Administration began regulating vehicle design. Significant design requirements include lap and shoulder belts in front seat positions, and, more recently, automatic safety belts or air bags in front seat positions, head restraints in front seat positions, reinforcing side and roof beams, and the center-mounted brake light. The most significant future advance will be the provision of full front seat air bags in all passenger vehicles. As much as one-quarter of brain trauma can be prevented or reduced in severity by this measure alone. Further safety requirements should include head restraints in rear positions, a-pillar, b-pillar, and roof padding, antilock brakes, and a vehicle rollover standard.
The effectiveness of airbags was estimated in a recent paper by assuming that they do not affect ejection probability and protect only in frontal and near-frontal crashes; the impact-reducing effectiveness in such crashes was assumed equal to that of lap/shoulder belts. The effectiveness, estimated as 18%, thus depends on the distribution of crashes by direction of impact and the incidence of ejection. Ejection rates and impact directions are markedly different for single-car as compared to two-car crashes and as a function of driver age and alcohol use. This raises the possibility that the overall effectiveness estimates might reflect an average of higher effectiveness for drivers more likely to be responsible for crashes (youths, drunks, those involved in single-car crashes) and a lower effectiveness for those less likely to be responsible (non-youths, the sober, and those involved in two-car crashes). By using FARS data for 1975-1986 to distribute fatal crashes by impact direction under various conditions, airbag effectiveness was calculated under these same conditions. Although substantial dependencies on impact direction were found, the fraction of all fatalities that were frontals remained surprisingly constant. It is concluded that effectiveness does not depend much on driver age or alcohol consumption, but is greater for two-car crashes than for single-car crashes (21% compared to 16%).
Enactment of seatbelt legislation in Maryland presented the opportunity to compare seatbelt compliance among seriously injured drivers admitted to a Level I trauma center and to establish levels of severity, length of stay, and hospital cost differences among the study population. Fifty-five randomly selected drivers were examined from a total surgical population of 689. Seatbelt compliance rate was 41.8%, reflecting the rate in the community. Seatbelts reduced the total number of injuries by 34%, major injuries by 57%, and minor injuries by 20%. No deaths occurred among the belted group. The unbelted group had a mean Injury Severity Score two times as great as the belted group and were hospitalized 1.6 times longer at double the cost. Major injuries to the face, chest, and pelvic regions were prevented by the seatbelt. Among the belted group, severe injuries did occur to the head, neck, and abdominal regions. It is recommended that both air bags and automatic restraining devices be required for all drivers if the trauma occurring daily on highways is to be eliminated and acute hospital cost minimized.
Seat belt use was observed in 1,628 cars with air bags and manual belts and 34,223 cars with manual seat belts only. Sixty-six percent of drivers in cars with air bags wore seat belts compared to 63 percent of drivers in cars with manual belts only. The study found no evidence for the speculation that drivers with air bags will reduce their seat belt use because they believe an air bag alone provides sufficient protection.
Motor vehicle crashes account for approximately one-half of all hospitalized patients with brain injury. Therefore, measures to reduce the frequency and severity of injuries from motor vehicle crashes have the potential for making a substantial impact on the incidence and severity of brain trauma. Occupant restraints, including seat belts and air bags, have been proven highly effective in preventing injuries, yet the specific benefits for the brain, the face, and the cervical spine provided by air bags have not been widely publicized. Air bags prevent the violent whiplash motion of the head in a frontal crash, resulting in a more controlled deceleration of the brain. Wrenching forces exerted on the cervical spine are attenuated, and the face is protected from contact with hard or lacerating surfaces. Furthermore, compliance is not a problem with air bags. When a car is equipped with air bags, they are in effect 100% of the time, which is important for the protection of high risk groups, such a teenage boys, who tend to wear seat belts less often than other groups. It is estimated from national data and from epidemiological studies that air bags could have prevented or reduced brain injury for 25% of the hospitalized, brain-injured population. If provided as standard equipment on both the driver and the passenger side, air bags could do more to reduce the toll of brain trauma than any other available intervention. Air bags were ready for introduction into the marketplace 15 years ago. Since then, approximately 150,000 preventable deaths and more than 1,500,000 preventable brain injuries have occurred.(ABSTRACT TRUNCATED AT 250 WORDS)
The paper examines the types of head injury sustained by restrained front-seat car occupants in frontal collisions. Injuries are classified into soft tissue, diffuse and focal brain injuries and facial bone or skull fractures. Survivors seldom sustain focal injuries although these are common amongst fatalities. The contact sources within the car are described. Intruding structures and high crash severities are typically associated with high rates of the more severe injuries from steering wheel contact, although some are sustained with intrusion below 11 cm. Low-speed impact testing on nondeployed airbag-equipped wheels is suggested. Toughened glass windscreens are overrepresented amongst those sustaining injuries from glazing materials. Test procedures to reduce injuries from pillar contacts should take account of the dynamic effects of an intruding pillar. Contacts with objects outside the car caused higher rates of severe fractures and brain injury; however, the total numbers are greater from interior contacts.
Automotive airbag technology has reduced the number of injuries and fatalities resulting from motor vehicle crashes. With the increasingly frequent application of this safety feature in automobiles, recent reports of airbag-associated injuries have emerged, including ocular and non-lethal cardiac trauma. We report three cases of airbag-related upper extremity injuries seen at a level-I trauma center over a 6-month period. A heightened awareness of this type of injury in patients injured in motor vehicle crashes with airbag deployment is recommended. The awareness, identification, and management of these high energy injuries will take on added meaning as the airbag technology becomes universally applied.
To determine the relationship between airbags and lower extremity injuries, 10 drivers admitted to a level-I trauma center with substantial lower extremity trauma incurred in crashes involving airbag-equipped vehicles were studied in depth with regard to their injuries, the circumstances of the crashes, and the medical charges for the acute management of those injuries.
During the clinical investigation portion of this study, we photographed lower extremity injuries, both soft tissue and radiographs, and performed a detailed surgical exploration during the debridement of open wounds or fracture fixation to treat them appropriately and to define the mechanism of injury, the fracture pattern, the pattern of soft-tissue insult, and the extent of periosteal stripping. We recorded the hospital and professional charges associated with the acute management not only of these injuries, but of the other injuries as well. The analysis performed for each case included a detailed crash reconstruction, including force, contact point, and vehicle intrusion data. Particular attention was paid to the dashboard and toe pan areas to determine deformation and intrusion and their association with thigh, leg, and foot injuries. Pertinent deformation and trajectory information was entered into the Calspan Reconstruction of Accident Speeds on the Highway (CRASH) computer program to generate a delta V or change in velocity measurement used as a measure of collision severity. When field data were incompatible with the limitations of the CRASH program, manual calculations such as "slide to stop" and conservation of momentum formulas were used.
The seven male and three female drivers had a mean age of 39.4 years. Only four used seatbelt restraints. The mean delta V was 28.3 mph and the mean maximum crush was 32.4 inches. The mean Injury Severity Score of 13.2. Musculoskeletal injuries included 11 foot/ankle fractures, 6 tibial fractures, 2 patellar fractures, 6 femoral fractures, and two acetabular/pelvic fractures. Other trauma included abdominal, thoracic, head and upper torso injuries, it seems that these safety devices do not prevent injuries to the lower extremity.
Details on airbag injuries to the upper extremity are relatively unknown to clinicians. The injuries presented here should provide a clear understanding of the mechanisms of forearm, hand, and wrist injuries that may be seen by emergency room physicians.
From our crash investigations of 325 airbag-equipped passenger cars, a subset of upper extremity injuries are presented that are related to airbag deployments.
Minor hand, wrist, or forearm injuries--contusions, abrasions, and sprains--are not uncommonly reported. Infrequently, hand fractures have been sustained and, in isolated cases, fractures of the forearm bones or of the thumb, wrist, and fingers. The close proximity of the forearm to the airbag module door is related to most of the fractures identified. Steering wheel airbag deployments can fling the hand-forearm into the instrument panel, rearview mirror, or windshield, as indicated by contact scuffs, tissue debris, or the star burst (spider web) pattern of windshield breakage in fron of the steering wheel.
Minor injuries of the upper extremity can occur when contacted by the deploying airbag either directly or by flinging the hand-forearm into interior car structures. Fractures of the forearm are rare and usually are due to direct impact by the forceful opening of the airbag module door.
An elderly woman was the driver and sole occupant of a midsize car involved in a minor collision with a standard sized automobile. She was restrained with a lap and shoulder belt and the air bag was deployed. Yet she suffered fatal chest injuries. No injuries were sustained by the unrestrained driver and passenger of the larger vehicle. Despite maximum restraint in a fully functioning new model car, even a minor collision can be fatal.
Loadings induced by deploying currently representative air bags were studied with driver surrogates (anesthetized swine) leaning against the system during inflation. Torso injury mechanisms were studied in a physiologic model, supported against a static steering wheel-mounted air bag system. Severe and extensive chest and abdominal injuries to the swine were observed in the tests. Loading caused by air bag deployment can occur in either of two phases. The first phase represents the initial punch out of the bag from the module; the second phase represents the membrane force of the inflating bag. Statistical analysis indicated that punch out induced injury because of the high rate of loading to the surrogate body region in direct contact with the air bag module. Membrane forces induced injury by high compression over a larger area. Punch-out loading might be reduced by allowing the bag to escape from other parts of the container not in contact with the driver during deployment. Loading by the inflating bag might be reduced by using a compliant steering system to support the module. The amount and rate of generated gas had only marginal effect on the cumulative injury. Even an inflator with inadequate gas output to protect a properly seated occupant had sufficient energy to induce severe injuries in a surrogate in contact with the inflating module. Analysis of the field relevance of the results must consider not only the injury potential given that a driver is in direct contact with the air bag module at the time of deployment, but also the expected field frequency of such an event. Analysis of the field relevance of the results must also consider the correlation of the laboratory test environment with real-world exposure.
Today an increasing number of automobiles are being equipped with additional passive safety devices: driver and passenger airbags. To examine the efficiency of the airbag in real road traffic accidents, a collective study was conducted from 181 traumatology centres throughout Germany. The inquiry was answered by 81 per cent of the medical centres contacted. From the evaluation of 122 accident victims in 1993 who were protected with an airbag the following was concluded. The patients treated in surgical and in traumatological departments suffered predominantly superficial injuries of the head, cervical vertebra and thorax. Some of these chiefly superficial wounds, such as abrasions and bruises, were initiated by contact with the airbag. It is remarkable that 72.1 per cent of the airbag-protected patients suffered a maximum of MAIS 2. What is also notable is the continuing high number of patients suffering from severe injuries (AIS 3+) of the lower extremities.
This paper presents the dynamic injury tolerances for the female humerus and forearm derived from dynamic 3-point bending tests using 22 female cadaver upper extremities. Twelve female humeri were tested at an average strain rate of 3.7+/-1.3%/s. The strain rates were chosen to be representative of those observed during upper extremity interaction with frontal and side airbags. The average moment to failure when mass scaled for the 5th centile female was 128+/-19 Nm. Using data from the in situ strain gauges during the drop tests and geometric properties obtained from pretest CT scans, an average dynamic elastic modulus for the female humerus was found to be 24.4+/-3.9 GPa. The injury tolerance for the forearm was determined from 10 female forearms tested at an average strain rate of 3.94+/-2.0%/s. Using 3 matched forearm pairs, it was determined that the forearm is 21% stronger in the supinated position (92+/-5 Nm) versus the pronated position (75+/-7 Nm). Two distinct fracture patterns were seen for the pronated and supinated groups. In the supinated position the average difference in fracture time between the radius and ulna was a negligible 0.4+/-0.3 ms. However, the pronated tests yielded an average difference in fracture time of 3.6+/-1.2 ms, with the ulna breaking before the radius in every test. This trend implies that in the pronated position, the ulna and radius are loaded independently, while in the supinated position the ulna and radius are loaded together as a combined structure. To produce a conservative injury criterion, a total of 7 female forearms were tested in the pronated position, which resulted in the forearm injury criterion of 58+/-12 Nm when scaled for the 5th centile female. It is anticipated that these data will provide injury reference values for the female forearm during driver air bag loading, and the female humerus during side air bag loading.
To describe occupant and crash characteristics in the first 27 publicly released investigations of air-bag-related fatalities.
A retrospective review of the first 27 released crash investigations of air-bag-induced fatalities was conducted. Data were obtained by the National Highway Traffic Safety Administration.
Three separate groups of occupants are described: adult drivers, school-aged children riding in the right front passenger seat, and infants installed into rear-facing infant car seats placed into the right front passenger seat. Female drivers were significantly likely to be short-statured. Male drivers tended to be slumped over the wheel. Eleven children (100%) were improperly restrained and thrown forward by preimpact braking. Adults tended to have serious chest injuries, while children tended to have CNS or neck injuries. All three infants had fatal CNS injuries. The average deltaV (change in the vehicle's velocity at the moment of impact) was 12 mph and the average bumper crash was 8.8 inches.
Air bags can cause fatal injury to car occupants in low- or moderate-speed crashes. Data suggest that proximity to the air bag at the time of deployment is the critical risk factor for fatal injury.
The aim of our study was to analyze the injury mechanism of upper extremity fractures in car crashes, to create a basis for developing prophylactic devices.
During 1985-1995, 3,260 restrained car drivers (1,228 front-seat passengers) were injured in 9,380 crashes involving cars. A total of 179 drivers (5.5%) (front-seat passengers: n = 53, 4.3%) sustained fractures of the arm. The hand (25%), wrist (23%), and forearm (23%) were affected most often, and the elbow (9%), upper arm (10%), and shoulder (10%) were seldom affected. No considerable differences of the injury mechanism were found comparing drivers with front-seat passengers. Fractures were mainly caused by head-on collisions (n = 119, 51%) or multiple collisions (n = 78, 34%). In 73% of the crashes (n = 166), delta-v exceeded 30 km/h (18.6 mph). A lower Delta-v resulted mainly in fractures affecting the shoulder and wrist.
Because more than half of the upper extremity fractures resulted from a direct impact to the hand, arm, or both, modifications to improve the energy absorption by padding dashboard and inner door or by additional airbags are promising.
Injuries trends of passenger car drivers in head-on collisions are identified based on crash data extracted from the National Automotive Sampling System. Annual injury incidence levels are estimated for years 1990-2007. Over that period, the number of crashes is predicted to rise by 71%. However, the number of serious injuries to drivers is expected to rise by only 41% and driver fatalities are anticipated to decrease by 9%. Meantime, the types of injuries suffered by drivers are changing. Year-to-year shifts in injury patterns result from changes in vehicle size classes within the US vehicle fleet population and increases in seat belt use and air bag availability. The effectiveness of air bags in saving lives is estimated to be 30%, and with more air bag-equipped cars on the road, the probability of sustaining a life-threatening head or a torso injury is reduced. Air bags, however, are not as effective in preventing upper and lower extremity injuries, and thus arm and leg injuries will become more prevalent in years to come.
This analysis provided effectiveness estimates of the driver-side air bag while controlling for severity of the crash and other potential confounders.
Data were from the National Automotive Sampling System (1993-1996). Injury severity was described on the basis of the Abbreviated Injury Scale, Injury Severity Score, Functional Capacity Index, and survival. Ordinal, linear, and logistic multivariate regression methods were used.
Air bag deployment in frontal or near-frontal crashes decreases the probability of having severe and fatal injuries (e.g., Abbreviated Injury Scale score of 4-6), including those causing a long-lasting high degree of functional limitation. However, air bag deployment in low-severity crashes increases the probability that a driver (particularly a woman) will sustain injuries of Abbreviated Injury Scale level 1 to 3. Air bag deployment exerts a net injurious effect in low-severity crashes and a net protective effect in high-severity crashes. The level of crash severity at which air bags are protective is higher for female than for male drivers.
Air bag improvement should minimize the injuries induced by their deployment. One possibility is to raise their deployment level so that they deploy only in more severe crashes.
To evaluate the effect driver-side and passenger-side airbags have had on the incidence and severity of maxillofacial trauma in victims of automobile accidents.
Retrospective analysis of all automobile (passenger cars and light trucks) accidents reported in 1994.
New York State.
Of the 595910 individuals involved in motor vehicle accidents in New York in 1994, 377054 individuals were initially selected from accidents involving cars and light trucks. Of this subset, 164238 drivers and 62755 right front passengers were selected for analysis.
Each case is described in a single record with approximately 100 variables describing the accident, eg, vehicle, safety equipment installed and utilized or deployed, occupant position, patient demographics, International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM) diagnoses, and procedural treatments rendered. A maxillofacial trauma severity scale was devised, based on the ICD-9-CM diagnoses.
Individuals using airbags and seat belts sustained facial injuries at a rate of 1 in 449, compared with a rate of 1 in 40 for individuals who did not use seat belts or airbags (P<.001). Those using airbags alone sustained facial injuries at the intermediate rate of 1 in 148, and victims using seat belts without airbags demonstrated an injury rate of 1 in 217 (P<.001).
Use of driver-side airbags, when combined with use of seat belts, has resulted in a decrease in the incidence and severity of maxillofacial trauma.
In a sample of relatively low speed frontal collisions (mean collision speed change of 40.7 kph) the only major injury suffered by the partly or fully restrained occupant was a femur fracture. However, femur load measurements from standardized barrier crash tests for similar vehicles at a greater speed change (mean of 56.3 kph) showed that in almost all the cases, the occupant's femur would not have fractured because the loads were below fracture threshold. In order to address this discrepancy, the load in the femurs of the occupants in the crash sample were estimated and compared with the femur fracture threshold. Femur load was estimated by inspecting the scene and measuring deformations in each vehicle, defining occupant points of contact and interior surface intrusion, and calculating crash change in velocity and deceleration. From this data, the measured femoral loads from standardized crash test data in a comparable vehicle were scaled to the actual crash by considering crash deceleration, occupant weight, and restraint use. All the occupants (7 males, average age 26.7 years, 13 females, average age 36 years) sustained at least a transverse midshaft fracture of the femur with comminution, which is characteristic of axial compressive impact, causing bending and impaction of the femur. However, the estimated average maximum axial load was 8187 N (S.D. = 4343N), and the average probability for fracture was only 19% (based on the femur fracture risk criteria). In 13 crashes the fracture probability was less than 10%. Two factors were considered to explain the discrepancy. The occupant's femur was out of position (typically the driver's right front leg on the brake) and did not impact the knee bolster, instead hitting stiffer regions of the dashboard. Also, since most victims were drivers with their foot on the brake to avoid the collision, additional compressive force on the femur probably resulted from muscle contraction due to bracing for impact. Adding the estimated muscle load on the femur to the estimated external load increased the femur loads beyond threshold, explaining the fracture in all but one case. Since crash tests using dummies cannot simulate out of position occupants or muscle contraction loading, they may underestimate the total load acting on the femur during actual impacts where the driver is bracing for the crash. These results may have implications for altering knee bolster design to accommodate out of position occupants and the additional load caused by muscle forces during bracing.
No studies have been reported on the frequency and aetiology of facial injuries due to MVAs in Queensland. This study aims to investigate the incidence, aetiology, age and sex distribution of facial injuries resulting from MVAs for a period of three years.
Cases were identified from the Motor Accident Insurance Commission, Queensland. Information including the type of injury sustained, the time, age and role of the patient in the accident were recorded and analysed.
There was an average maxillofacial injury incidence of 4.8/100,000 per year, 53.5 per cent in males and 46.5 per cent in females. A peak incidence was found for both sexes aged 18 to 22 years. In males, 57 per cent of facial injuries occurred in this age group compared to 41 per cent in females.
Maxillofacial injuries as a result of MVAs are still relatively high regardless of the legislation for compulsory seatbelt use. Recent advances in seatbelt systems have the potential to reduce the risk of head and face impacts. The airbag is also well established as an effective means of preventing serious head and face injury. However, more research is required to further reduce the incidence of maxillofacial injuries as a result of MVAs.
To estimate the association of driver air bag presence with driver fatality in road traffic crashes.
Matched pair cohort study.
All passenger vehicle crashes in the United States during 1990-2000 inclusive.
51 031 driver-passenger pairs in the same vehicle.
Relative risk of death within 30 days of a crash.
Drivers with an air bag were less likely to die than drivers without an air bag (adjusted relative risk 0.92 (95% confidence interval 0.88 to 0.96)). This estimate was nearly the same whether drivers wore a seat belt (adjusted relative risk 0.93) or not (0.91). Air bags were associated with more protection for women (0.88 (0.82 to 0.93)), than for men (0.94 (0.90 to 0.99)). Drivers wearing a seat belt were less likely to die than unbelted drivers (0.35 (0.33 to 0.36)). Belted drivers with an air bag were less likely to die than unbelted drivers without an air bag (0.32 (0.30 to 0.34)). Conclusions: If the associations are causal the average risk of driver death was reduced 8% (95% confidence interval 4% to 12%) by an air bag. Benefit was similar for belted and unbelted drivers and was slightly greater for women. However, seat belts offered much more protection than air bags.
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.
To examine the relationship between the use of restraining devices and the incidence of specific facial fractures in motor vehicle crashes.
Retrospective analysis of patients with facial fractures following a motor vehicle crash.
University of Alabama at Birmingham Hospital level I trauma center from 1996 to 2000.
Of 3731 patients involved in motor vehicle crashes, a total of 497 patients were found to have facial fractures as determined by International Classification of Diseases, Ninth Revision (ICD-9) codes. Facial fractures were categorized as mandibular, orbital, zygomaticomaxillary complex (ZMC), and nasal.
Use of seat belts alone was more effective in decreasing the chance of facial fractures in this population (from 17% to 8%) compared with the use of air bags alone (17% to 11%). The use of seat belts and air bags together decreased the incidence of facial fractures from 17% to 5%.
Use of restraining devices in vehicles significantly reduces the chance of incurring facial fractures in a severe motor vehicle crash. However, use of air bags and seat belts does not change the pattern of facial fractures greatly except for ZMC fractures. Air bags are least effective in preventing ZMC fractures. Improving the mechanics of restraining devices might be needed to minimize facial fractures.
The purpose of this study was to identify and analyze factors contributing to both airbag deployment and resulting head injuries (HIs) and to quantify the effect of airbag deployment on head injuries, in terms of odds of head injury and severity, in severe motor vehicle collisions (MVCs).
Data were derived from severely injured (Injury Severity Score [ISS] > 12) drivers treated at Ontario's lead trauma hospitals (n = 1,272), and included all MVC driver deaths in the province (n = 665) from 1997-98. We conducted an epidemiologic description and a case-control study to compare drivers with and without HIs. Statistical analysis included Pearson's chi2, Wilcoxon rank-sum, and multiple logistic regression tests.
Seventy-one percent of drivers were men, peaking in the 25- to 34-year age group. The most common impact involved multiple vehicles (62%) approaching each other. Overall, 59% of crashes had a frontal location of impact. HIs were significantly associated with a lower age (median, 36 vs. 43 years), seat belt use (53% vs. 59%), and airbag deployment (7% vs. 10%), with higher ISS (median, 34 vs. 22), ejection (20% vs. 10%), and mortality rate (44% vs. 35%). Airbag deployment was associated with higher age and seat belt use, and lower ISS, ejection, and deaths. Importantly, there were fewer HIs with the deployment of an airbag (64% vs. 73%) and a lower severity of HI. When logistic regression was used to control for the effects of possible confounders, airbag deployment was not statistically associated with one's odds of HI (odds ratio, 0.827; 95% confidence interval, 0.560-1.220), but ISS, age, and ejection were.
Airbag deployment did not significantly lower a driver's odds of head injury in a severe MVC, but it did significantly lower the severity of head injury. This is a significant finding, given that 72% of our study population sustained a head injury and the importance of lowering the severity of these head injuries in terms of patients' ultimate outcome. The most important factor associated with head injuries was ejection, which nearly doubled a driver's odds of head injury (odds ratio, 1.759; 95% confidence interval, 1.201-2.577). This reinforces the supplementary protective effect of an airbag and that "buckling up" and keeping occupants in the vehicle is of primary importance in the prevention of head injuries.
This paper presents dummy and cadaver experiments designed to investigate the injury potential of an out-of-position small female head and neck from a deploying side airbag.
Seat-mounted, thoracic-type, side airbags were selected for this study to represent those currently available on selected luxury automobiles. A computer simulation program was used to identify the worst case loading position for the small female head and neck. Once the initial position was identified, experiments were performed with the Hybrid III 5th percentile dummy and three small female cadavers, using three different inflators.
Peak head center of gravity (CG) accelerations for the dummy ranged from 71x g to 154 x g, and were greater than cadaver values, which ranged from 68 x g to 103 x g. Peak neck tension as measured at the upper load cell of the dummy increased with inflator aggressivity from 992 to 1670N. A conservative modification of the US National Highway Traffic Safety Administration's (NHTSA's) N(ij) proposed neck injury criteria, which combines neck tension and bending, was used. All values were well below the 1.0 injury threshold for the dummy and suggested a very low possibility of neck injury. In agreement with this prediction, no injuries were observed.
Even in a worst case position, small females are at low risk of head or neck injuries under loading from these thoracic-type airbags; however, injury risk increases with increasing inflator aggressivity.
NASS 1998-2000 was queried to determine the frequency of serious injuries in multiple impact crashes and the distribution of injuries by crash sequence. The data set included all passenger cars and light trucks in NASS/CDS. The results showed that 42% of the MAIS 3+ injuries were in crashes that involved more than one harmful event. Approximately 24% of the MAIS 3+ injuries involved two harmful events, and 18% involved 3 or more harmful events. For multiple crashes with serious injuries, the most frequent initial impact direction was frontal (50%) followed by side (44.9%). The most frequent second impact was side (48.4%) followed by frontal (27.6%). The most harmful sequences were side-side (27.7%), front-side (15.8%) and front-front (14.9). The data suggests the need for further investigation and classification complex multiple impact crashes to aid in the in the design of safety systems.
In 1997, the National Highway Traffic Safety Administration amended its requirements for frontal crash performance under Federal Motor Vehicle Safety Standard 208 to temporarily allow 30 mi/h (48 km/h) sled tests with unbelted dummies as an alternative to 30 mi/h head-on rigid-barrier vehicle tests. This change permitted automakers to reduce airbag inflation forces so that they would be less likely to injure occupants who are close to airbags when they first deploy. Most vehicle models were sled-certified starting in model year 1998. Airbag-related deaths have decreased since 1997; however, controversy persists about whether reduced inflation forces might be decreasing protection for some occupants in high-severity frontal crashes. To examine the effects of the regulatory changes, this study computed rate ratios (RR) and 95% confidence intervals (95% CI) for passenger vehicle driver deaths per vehicle registration during 2000-2002 at principal impact points of 12 o'clock for 1998-99 model year vehicles relative to 1997 models. Passenger vehicles included in the study had both driver and passenger front airbags, had the same essential designs during the 1997-1999 model years, and had been sled-certified for drivers throughout model years 1998 and 1999. An adjustment was made for the higher annual mileage of newer vehicles. Findings were that the effect of the regulatory change varied by vehicle type. For cars, sport utility vehicles, and minivans combined, there was an 11 percent decrease in fatality risk in frontal crashes after changing to sled certification (RR = 0.89; 95% CI = 0.82-0.96). Among pickups, however, estimated frontal fatality risk increased 35 percent (RR = 1.35; 95% CI = 1.12-1.62). For a broad range of frontal crashes (11, 12, and 1 o'clock combined), the results indicated a modest net benefit of the regulatory change across all vehicle types and driver characteristics. However, the contrary finding for pickups needs to be researched further.
This article presents a broad review of the literature on frontal air bag field performance, starting with the initial government and industry projections of effectiveness and concluding with the most recent assessments of depowered systems. This review includes as many relevant metrics as practicable, interprets the findings, and provides references so the interested reader can further evaluate the limitations, confounders, and utility of each metric. The evaluations presented here range from the very specific (individual case studies) to the general (statistical analyses of large databases). The metrics used to evaluate air bag performance include fatality reduction or increase; serious, moderate, and minor injury reduction or increase; harm reduction or increase; and cost analyses, including insurance costs and the cost of life years saved for various air bag systems and design philosophies. The review begins with the benefits of air bags. Fatality and injury reductions attributable to the air bag are presented. Next, the negative consequences of air bag deployment are described. Injuries to adults and children and the current trends in air bag injury rates are discussed, as are the few documented instances of inadvertent deployments or non-deployment in severe crashes. In the third section, an attempt is made to quantify the influence of the many confounding factors that affect air bag performance. The negative and positive characteristics of air bags are then put into perspective within the context of societal costs and benefits. Finally, some special topics, including risk homeostasis and the performance of face bags, are discussed.
Safety of the airbag supplemental restraint system (airbag) is a well-known concern. Although many lives are saved each year through airbag use, injuries continue to occur, especially to the head. Airbag safety research has focused primarily on severe injuries, while minor and moderate injuries have been largely ignored.
In this study, 205,977 injury cases from the 1995 to 2001 National Automotive Sampling System (NASS)/ Crashworthiness Data System (CDS) were surveyed to determine the prevalence of AIS 1 and 2 facial and brain loss of consciousness (LOC) injuries and determine if these injuries are a concern. The query was focused on frontal impacts in vehicles equipped with airbags. Only occupants wearing appropriate seatbelts were included in this study so that the airbag would provide occupant protection under optimal conditions. Of the 205,977 injury cases studied, 2.4% met this criterion.
From the data gathered, the trends seem to indicate an increase in these specific injuries, both in terms of the total number and the proportion to all injury cases. In 1995, AIS 1 and 2 head injuries accounted for 96.5% of all head injuries caused by airbags. By 2001, the percentage had risen 3.0% to 99.5%. Injuries occurring in vehicles equipped with first-generation versus second generation airbags were compared, and data seem to suggest that there is a higher rate of minor and moderate head injuries when occupants are in second-generation airbag-equipped vehicles, even when appropriate lap and shoulder belts are used.
The short timeframe surveyed prevents drawing meaningful conclusions about statistical significance, but the graphical representations of the data in this study underscore an urgent need for further investigation based on current trends in order to understand the issue of minor and moderate head injury prevention in regard to airbags.