Far-side Occupants Research Articles

Characterization of far-side occupant chest injuries in oblique side impact considering uncertainty

Purpose Oblique side impact is a common form of impact in life, and the far-side occupant’s chest is highly susceptible to injury in the impact process. This study analyzed the effects of different factors on the chest response of far-side occupants in oblique side impacts. Methods In this study, a simplified sled model was developed. After that, five factors, namely, impact velocity, impact angle, seat friction coefficient, seatbelt friction coefficient, and seatbelt force-limiting were considered as uncertain variables and randomly sampled. Sixteen sets of impact simulations with different parameters were performed using the sampled results to evaluate the farside occupant chest response. Results Results showed that the impact velocity was positively correlated with the chest deflection and chest acceleration, with correlation coefficients 0.77 and 0.92, respectively, and the impact angle was negatively correlated with the chest deflection and chest acceleration, with correlation coefficients -0.83 and -0.54, respectively. The seatbelt friction coefficient and force limiting value were positively and negatively correlated with the occupant’s chest response, respectively. Conclusions The results suggested that multiple variables collectively influenced occupant injury, and random combinations of different variables may play a critical role in impact outcomes. This study provides a reference for the study of occupant injury in far-side impacts.

Side-Impact Collisions involving Passenger Vehicles in Real-World Crashes


 
 
 In Malaysia, 6,570 fatalities were recorded as a result of road deaths in 2016. From that figure, 1,197 or 18.2% were involved in side- impact collisions. An in-depth crash investigation study was conducted by utilizing data from the MIROS crash investigation database (MICARS) to better understand the mechanism and characteristics of the crash and to correlate the impact and damages profile with the injury outcome of the involved occupants related to the side-impact crash. The data obtained from MICARS for this study was selected from 2007 until 2016, during which MIROS had investigated 794 for both East and West Malaysia. Out of that number, 41 cases involving passenger vehicles were selected for analysis purposes. The results found that the risk of serious or fatal injury to nearside occupants was eight times higher compared to the far-side occupants. Besides that, the use of the restraint system does not show a significant association with the occupants' fatality. In a conclusion, car manufacturers should equip all new passenger vehicle models with passive safety features such as side and curtain airbags and should also increase the rigidity of the side structure of the said vehicles to reduce the injury severity level of the occupants. Furthermore, the government needs to review all these issues together with the vehicle manufacturers to make it become a Malaysian Standard before mandating it for all passenger vehicles in Malaysia. Thus, continuous efforts and commitment by car manufacturers and the government are essential to produce safer cars with proper and adequate active and passive safety features.
 
 

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

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

Development and Validation of the Total HUman Model for Safety (THUMS) Version 5 Containing Multiple 1D Muscles for Estimating Occupant Motions with Muscle Activation During Side Impacts.

Accurate prediction of occupant head kinematics is critical for better understanding of head/face injury mechanisms in side impacts, especially far-side occupants. In light of the fact that researchers have demonstrated that muscle activations, especially in neck muscles, can affect occupant head kinematics, a human body finite element (FE) model that considers muscle activation is useful for predicting occupant head kinematics in real-world automotive accidents. In this study, we developed a human body FE model called the THUMS (Total HUman Model for Safety) Version 5 that contains 262 one-dimensional (1D) Hill-type muscle models over the entire body. The THUMS was validated against 36 series of PMHS (Post Mortem Human Surrogate) and volunteer test data in this study, and 16 series of PMHS and volunteer test data on side impacts are presented. Validation results with force-time curves were also evaluated quantitatively using the CORA (CORrelation and Analysis) method. The validation results suggest that the THUMS has good biofidelity in the responses of the regional or full body for side impacts, but relatively poor biofidelity in its local level of responses such as brain displacements. Occupant kinematics predicted by the THUMS with a muscle controller using 22 PID (Proportional-Integral- Derivative) controllers were compared with those of volunteer test data on low-speed lateral impacts. The THUMS with muscle controller reproduced the head kinematics of the volunteer data more accurately than that without muscle activation, although further studies on validation of torso kinematics are needed for more accurate predictions of occupant head kinematics.

Occurrence of Serious Injury in Real-World Side Impacts of Vehicles with Good Side-Impact Protection Ratings

Objective: The Insurance Institute for Highway Safety (IIHS) introduced its side impact consumer information test program in 2003. Since that time, side airbags and structural improvements have been implemented across the fleet and the proportion of good ratings has increased to 93% of 2012–2014 model year vehicles. Research has shown that drivers of good-rated vehicles are 70% less likely to die in a left-side crash than drivers of poor-rated vehicles. Despite these improvements, side impact fatalities accounted for about one quarter of passenger vehicle occupant fatalities in 2012. This study is a detailed analysis of real-world cases with serious injury resulting from side crashes of vehicles with good ratings in the IIHS side impact test.Methods: NASS-CDS and Crash Injury Research and Engineering Network (CIREN) were queried for occupants of good-rated vehicles who sustained an Abbreviated Injury Scale (AIS) ≥ 3 injury in a side-impact crash. The resulting 110 cases were categorized by impact configuration and other factors that contributed to injury. Patterns of impact configuration, restraint performance, and occupant injury were identified and discussed in the context of potential upgrades to the current IIHS side impact test.Results: Three quarters of the injured occupants were involved in near-side impacts. For these occupants, the most common factors contributing to injury were crash severities greater than the IIHS test, inadequate side-airbag performance, and lack of side-airbag coverage for the injured body region. In the cases where an airbag was present but did not prevent the injury, occupants were often exposed to loading centered farther forward on the vehicle than in the IIHS test. Around 40% of the far-side occupants were injured from contact with the struck-side interior structure, and almost all of these cases were more severe than the IIHS test. The remaining far-side occupants were mostly elderly and sustained injury from the center console, instrument panel, or seat belt. In addition, many far-side occupants were likely out of position due to events preceding the side impact and/or being unbelted.Conclusion: Individual changes to the IIHS side impact test have the potential to reduce the number of serious injuries in real-world crashes. These include impacting the vehicle farther forward (relevant to 28% of all cases studied), greater test severity (17%), the inclusion of far-side occupants (9%), and more restrictive injury criteria (9%). Combinations of these changes could be more effective.

Differences in Long-term Medical Consequences Depending on Impact Direction Involving Passenger Cars

Objective: There is limited knowledge of the long-term medical consequences for occupants injured in car crashes in various impact directions. Thus, the objective was to evaluate whether injuries leading to permanent medical impairment differ depending on impact direction.Methods: In total, 36,743 injured occupants in car crashes that occurred between 1995 and 2011 were included. All initial injuries (n = 61,440) were classified according to the Abbreviated Injury Scale (AIS) 2005. Injured car occupants were followed for at least 3 years to assess permanent medical impairment. The data were divided into different groups according to impact direction and levels of permanent impairment. The risk of permanent medical impairment was established for different body regions and injury severity levels, according to AIS.Results: It was found that almost 12% of all car occupants sustained a permanent medical impairment. Given an injury, car occupants involved in rollover crashes had the highest overall risk to sustain a permanent medical impairment. Half of the head injuries leading to long-term consequences occurred in frontal impacts. Far-side occupants had almost the same risk as near-side occupants. Occupants who sustained a permanent medical impairment from cervical spine injuries had similar risk in all impact directions (13%) except from rollover (17%). However, these injuries occurred more often in rear crashes. Most of the injuries leading to long-term consequences were classified as minor injuries by AIS for all impact directions.Conclusions: Studying crash data from a perspective of medical impairment is important to identify injuries that might not be prioritized only considering the AIS but might lead to lower quality of life for the occupant and also costs for society. These results can be used for road transport system strategies and for making priority decisions in vehicle design.

Crash Characteristics and Injury Patterns of Restrained Front Seat Occupants in Far-side Impacts

Objective: The study was conducted to determine the association between vehicle-, crash-, and demographic-related factors and injuries to front seat far-side occupants in modern environments.Methods: Field data were obtained from the NASS-CDS database for the years 2009–2012. Inclusion factors included the following: adult restrained front outboard-seated occupants, no ejection or rollovers, and vehicle model years less than 10 years old at the time of crash. Far-side crashes were determined by using collision deformation classification. Injuries were scored using the Abbreviated Injury Scale (AIS). Injuries (MAIS 2+, MAIS 3+, M denotes maximum score) were examined based on demographics, change in velocity, vehicle type, direction of force, extent zone, collision partner, and presence of another occupant in the front seat. Only weighted data were used in the analysis. Injuries to the head and face, thorax, abdomen, pelvis, and upper and lower extremity regions were studied. Odds ratios and upper and lower confidence intervals were estimated from multivariate analysis.Results: Out of 519,195 far-side occupants, 17,715 were MAIS 2+ and 4,387 were MAIS 3+ level injured occupants. The mean age, stature, total body mass, and body mass index (BMI) were 40.7 years, 1.7 m, 77.2 kg, and 26.8 kg/m2, respectively. Of occupants with MAIS 2+ injuries, 51% had head and 19% had thorax injuries. Of occupants with MAIS 3+ injuries, 50% had head and 69% had thorax injuries. The cumulative distribution of changes in velocities at the 50th percentile for the struck vehicle for all occupants and occupants with MAIS 2+ and MAIS 3+ injuries were 19, 34, and 42 km/h, respectively. Furthermore, 73% of MAIS 2+ injuries and 86% of MAIS 3+ injuries occurred at a change in velocity of 24 km/h or greater. Odds of sustaining MAIS 2+ and MAIS 3+ injuries increased with each unit increase in change in velocity, stature, and age, with one exception. Odds of sustaining injuries were higher with the presence of an occupant in the front seat at the MAIS 3+ level, although it was reversed at the lower level. The extent zone of 3+ increased the odds compared to the extent zones of 1 to 2 at both MAIS 2+ and MAIS 3+ injuries. Odds ratios and confidence intervals are given.Conclusions: The findings are as follows: head and thorax are the more frequently injured body regions, and the prevalence of cranium injuries is similar at both injury severities; thoracic injuries are more prevalent at the MAIS 3+ level; the presence of another front seat occupant plays a role in MAIS 3+ trauma; injuries continue to occur at changes in velocity representative of side impact environments; and mean demographic factors are close to mid-size automotive anthropometry, indicating the need to pursue this line of study. Because data were gathered from only 4 years, it would be important to include additional NASS-CDS database years, rescore injuries from previous years, and analyze other international databases to reinforce these findings for advancing safety for far-side occupants.

Injury severity of occupants in lateral collisions in standard and small vehicles: Analysis of ITARDA's in-depth investigation data

A retrospective analysis was performed to investigate the differences in occupant injury characteristics between standard and small vehicles in lateral collision. From the in-depth data of the Institute for Traffic Accident Research and Data Analysis (ITARDA) from 1993 to 2003, data were collected for 331 adults who were front-seat occupants involved in single lateral motor vehicle collisions. The accident information, the subjects’ medical data and the anatomical injury severity scores were examined. The involved passenger vehicles were classified as small or standard. Seatbelts were effective in decreasing the head–neck injury severity of far-side occupants of standard vehicles, but in small vehicles, no significant benefit was observed. In standard vehicles, far-side occupants suffered less severe injuries than near-side occupants, but this trend was not apparent in small vehicles. These differences may result from the smaller interior space of the smaller vehicles.

Protection of Children Restrained in Child Safety Seats in Side Impact Crashes

The performance of child restraint systems (CRS) in side impact motor vehicle crashes has been under study due to the injury and fatality burden of these events. Although previous research has quantified injury risk or described injured body regions, safety advances require an understanding of injury causation. Therefore, the objective was to delineate injury causation scenarios for CRS-restrained children in side impacts and document probable contact points in the vehicle interior. Two in-depth crash investigation databases, the Crash Injury Research and Engineering Network and the Partners for Child Passenger Safety Study, were queried for rear-seated, CRS-restrained children in side impact crashes who sustained Abbreviated Injury Scale 2+ injury. These cases were reviewed by a multidisciplinary team of physicians and engineers to describe injury patterns, injury causation, and vehicle components that contributed to the injuries. Forty-one occupants (average age, 2.6 years) met the inclusion criteria. Twenty-four were near side to the crash, 7 were far side, and 10 were center seated. The most common injuries were to the skull and brain with an increasing proportion of skull fracture as age increased. Head and spine injuries without evidence of head contact were rare but present. All thoracic injuries were lung contusions and no rib fractures occurred. Near-side head and face contacts points were along the rear vertical plane of the window and the horizontal plane of the window sill. Head and face contact points for center- and far-side occupants were along the edges of the front seat back and front seat head restraint. Head injuries are the target for injury prevention for children in CRS in side impact crashes. Most of these injuries are due to the contact; for near-side occupants, contact with the CRS structure and the door interior, for far- or center-seated occupants, contact with the front seat back. These data are useful in developing both educational and technological interventions to reduce the burden of injury to these children.

The Influence of Occupant Anthropometry and Seat Position on Ejection Risk in a Rollover

Purpose: During rollover crashes, ejection increases an occupant's risk of severe to fatal injury as compared to risks for those retained in the vehicle. The current study examined whether occupant anthropometry might influence ejection risk. Factors such as restraint use/disuse, seating position, vehicle type, and roll direction were also considered in the analysis. Methods: The current study examined occupant ejections in 10 years of National Automotive Sampling System (NASS) single-event rollovers of passenger vehicles and light trucks. Statistical analysis of unweighted and weighted ejection data was carried out. Results: No statistically significant differences in ejection rates were found based on occupant height, age, or body mass index. Drivers were ejected significantly more frequently than other occupants: 62 percent of unrestrained drivers were ejected vs. 51 percent unrestrained right front occupants. Second row unrestrained occupants were ejected at rates similar to right front–seated occupants. There were no significant differences in ejection rates for near- vs. far-side occupants. Conclusions: These data suggest that assessment of ejection prevention systems using either a 50th or 5th percentile adult anthropomorphic test dummy (ATD) might provide a reasonable measure of system function for a broad range of occupants. They also support the development of ejection mitigation technologies that extend beyond the first row to protect occupants in rear seat positions. Future studies should consider potential interaction effects (i.e., occupant size and vehicle dimensions) and the influence of occupant size on ejection risk in non-single-event rollovers.

Severe Injury to Near- and Far-Seated Occupants in Side Impacts by Crash Severity and Belt Use

Purpose: 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). Methods: 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. Results: 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. Conclusions: 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.

Finite element analysis of occupant head and neck injury mechanism during rollover crashes

A set of state-of-the-art Finite Element (FE) vehicle restraint system, crash dummy and whole body human models was integrated and validated against several quasi-static and dynamic rollover tests. HIII dummy responses during three selected trip-over scenarios were simulated using an FE vehicle model equipped with four different hypothetical roof stiffness values. Results indicated that both previous hypotheses on rollover injury mechanism, i.e. 'diving mechanism' and 'roof crush mechanism', are flawed. The results supported that 'diving' is the major injury mechanism in rollovers, but 'roof stiffness' (not 'roof crush') affects the head and neck injury risks for far-side occupants during 'diving' type of impacts. Traditional 'diving mechanism' neglected the fact that roof stiffness can change the vehicle and occupant kinematics in rollovers, and consequently affected the occupant injury risks. More rollover tests using both the dummy and the cadaver are needed to further validate the hypothesis proposed in this study.

Expected Differences and Unexpected Commonalities in Mortality, Injury Severity, and Injury Patterns Between Near Versus Far Occupants of Side Impact Crashes

To compare injury patterns and outcomes of near- and far-side collisions. Near- and far-side occupants in the Crash Injury Research and Engineering Network (CIREN) were compared for mortality and the occurrence of severe injuries (maximum abbreviated injury scale [MAIS] 3+). Regression models, adjusting for confounders, examined death and MAIS 3+ injuries as outcomes and near- or far-side position as an independent variable. CIREN findings were compared with those of the Crash Outcome Data Evaluation System (CODES), and the Maryland Automated Accident Reporting System. Of the 380 cases, 72% were in the near and 28% in the far position. Mortality was similar between groups within CIREN. Near-side occupants experienced a higher frequency of MAIS 3+ injuries for the thorax, abdomen, and lower extremities, and fewer MAIS 3+ head injuries than far-side occupants (35% vs. 46%, p = 0.06). Regression models revealed similar risk of MAIS 3+ head injuries among near- and far-side occupants. The most common structures contacting the head in far-side crashes (N = 62) were opposite side structures (52%) and other occupants (13%). Similar risks of head injuries among near- and far-side occupants were observed for the CODES data; however, lower risks of death were present among far-side drivers involved in crashes, based on CODES and Maryland Automated Accident Reporting System. Despite a lower incidence of thoracic, abdominal, and lower extremity injuries, far-side occupants experienced a similar risk of head injuries to that of near-side occupants. Contact patterns suggest that restraint systems fail to keep far-side occupants' heads from striking opposite side structures or other occupants.

A Comparison of Volunteers and Dummy Upper Torso Kinematics with and Without Shoulder Belt Slack in a Low Speed Side/Pre-Roll Environment

Objective. The objective of this study was to compare the occupant and dummy kinematics in a low-speed lateral environment with and without shoulder belt slack. Methods. A buck of a small European car was mounted on a side impact sled. The parameters evaluated were pulses, sitting location, and belt slack. A total of 24 tests were carried out. Three 50th-percentile male volunteers and one Hybrid III 50th-percentile male were tested. The pulses consisted of Pulse 1:+/- 0.7 g's pulse and Pulse 2: a -0.9 g pulse to simulate low-speed pre-roll/side events. Both pulses had a duration of 500 msec. Results. The peak lateral head excursion was higher in the far-side occupants than in the near-side occupants. Furthermore, for the far-side volunteers, lateral head displacements were lower in the no-slack condition than in the slack condition, at 388 ± 64 mm and 455 ± 84 mm respectively for Pulse 1 and at 138 ± 2 mm and 207 ± 70 mm for Pulse 2. The timing required to reach peak lateral displacement was higher in Pulse 1 than in Pulse 2. In comparison to the volunteers, the Hybrid III dummy lateral motion was lower. The peak lateral displacement in Pulse 1 was 231 mm with slack and 194 mm without and 98 mm and 107 mm for Pulse 2, respectively. Conclusions. The results obtained in this study indicate that removing seatbelt slack would be more beneficial for far-sided occupants than near-sided. They also point to the lack of biofidelity of the Hybrid III dummy in low g lateral pulses.

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

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

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

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

Side Impact Protection - Occupants in the Far-Side Seat

Much of the applied vehicle side impact occupant protection research to date has concentrated on occupants seated beside the struck side of vehicles. These occupants are defined as ‘near-side occupants’. Regulatory side impact test standards focus exclusively on this scenario. Real world crash evidence however has shown that occupants seated on the side away from the struck side, defined as ‘far-side occupants’, are still subject to a risk of injury. Relatively little research literature is available that addresses the protection of far-side occupants. Existing three-pint seat belt restraint systems were primarily designed for frontal impacts. Consequently, there is an inability for these systems to perform as effectively under lateral loading, compared to longitudinal loading. This is particularly the case for far-side occupant restraints, where the occupant's upper tom has often been observed to slip out from under the sash part of the seat belt system. This paper examines side impact epidemiology from an injury causation perspective, and endeavours to explain evidence indicating head injuries and seat belt related injuries constitute a significant proportion of all far-side impact injuries. Injury mechanisms and key dynamic parameters governing injury severity are detailed. Computer models simulating the dynamic motion of vehicle far-side occupants are described. Occupant kinematics and injury parameters from the models are then compared with real world crash case studies. The paper finally suggests vehicle design strategies which are likely to reduce far-side injuries. Some alternative restraint systems are proposed as potential countermeasures to reduce occupant injuries.

Injury severity of restrained front seat occupants in car-to-car side impacts

The influence of a number of factors, including age and particularly seating position, on the injury severity of restrained occupants was examined for 41 front-seat occupants seated adjacent to the impact (near side) and 38 sitting opposite the impacted side (far side) in car-to-car side collisions (center of impact: front door and B-pillar). Above an energy equivalent speed of 40 km/h all near-side occupants and about half of the far-side occupants sustained severe injuries. A logistic regression analysis showed that within range of 30–60 km/h (delta ν 20–60 km/h) the probability of severe injuries increased dramatically from approximately 20% to more than 90%; in these cases, far-side occupants had the same injury probability as near-side occupants only when the speed was 10 km/h higher. The main cause of death for 27 occupants seated on both sides was polytrauma, this was accompanied in two-thirds of the cases by serious head injuries. The second most frequent cause of death was head injury.