A matched-cohort analysis of belted front and rear seat occupants in newer and older model vehicles shows that gains in front occupant safety have outpaced gains for rear seat occupants

Previous studies have suggested that rear seat occupants are at lower risk of serious injury and death in crashes. However, over the last 10–15 years there have been significant changes in front seat safety systems. The aim of this study was to determine whether there is still a benefit for rear seated occupants compared to front seat occupants. A matched-cohort approach, using data on restrained occupants from the US National Automotive Sampling System (data years 1993–2007), was adopted. Conditional poisson regression modeling was used to evaluate the relative risk of AIS3+ injury in front (passenger and driver) and rear seat occupants, in vehicles of model year 1990–1996 compared to newer vehicles. Occupant age, belt type, and intrusion were additional variables in the model. The relative risk of AIS3+ injury for front and rear occupants was influenced by age and model year. For those aged 16–50 years in older vehicles, the front and rear seat offered similar levels of protection (RR = 1.14, CI = 1.09–1.19), however in newer model vehicles (1997–2007), the rear seat carried a higher risk of injury (RR = 1.98, CI = 1.90–2.06). For adults over 50 years, the rear seat carried a higher risk in both older and newer vehicles, and for 9–15 year olds, the rear seat carried a lower risk. These findings suggest that safety for front seat occupants has improved over the last decade, to the point where, for occupants over 15 years of age, the front seat is safer than the rear seat. While the benefit of rear seating for children aged 9–15 years has decreased over time, they are still at lower risk in the rear seat.     

Method to evaluate the effect of safety belt use by rear seat passengers on the injury severity of front seat occupants

Although the effectiveness of seat belts for reducing injury to rear seat passengers in traffic accidents has been well documented, the ratio of rear-seat passengers restrained by seatbelts remains lower than that of drivers or passengers in front seats. If passengers in rear seats do not wear seat belts, they may sustain unexpected injury to themselves when involved in accidents, and also endanger front occupants (drivers or front seat passengers). This paper focuses on the tendency of front seat occupants to sustain severer injuries due to forward movement of passengers in rear seats at the moment of frontal collisions, and evaluates the effectiveness of rear passengers' wearing seat belts in reducing injuries of front seat occupants. Since the occurrence of occupant injuries depends considerably on the crash severity, we proposed to use pseudo-delta V in regression analysis to represent velocity change during a collision when analyzing statistical accident data. As the crash severity can be estimated from pseudo-delta V, it becomes possible to make appropriate estimations even when the crash severity differs in data. The binary model derived from the ordered response model was used to evaluate the influence on the injury level based on pseudo-delta V, belted or unbelted status, gender and age. Occupants in cars with a hood in the case of car-to-car frontal collisions were extracted from the statistical data on accidents in Japan. Among 81,817 cars, where at least one passenger was present, a total of 6847 cars in which all passengers sustained injuries and which had at least one rear seat passenger aboard were analyzed. The number of killed or seriously injured drivers is estimated to decrease by around 25% if rear seat occupants come to wear seat belts. Also, the number of killed or seriously injured passengers in front seats is estimated to decrease by 28% if unbelted rear seat occupants come to wear seat belts. Thus, wearing of seat belts by previously unbelted rear seat passengers is considered effective in reducing not only injuries to the rear seat passengers themselves but also injuries to front seat occupants.     

Effect of wheelchair headrest use on pediatric head and neck injury risk outcomes during rear impact

Comparative risks or benefits to wheelchair-seated pediatric occupants in motor vehicles associated with wheelchair headrest use during rear impact were evaluated using pediatric head and neck injury outcome measures. A Hybrid III 6-year-old anthropomorphic test device (ATD), seated in identical WC19-compliant pediatric manual wheelchairs, was used to measure head and neck response during a 25 km/h (16 mph), 11 g rear impact. ATD responses were evaluated across two test scenarios: three sled tests conducted without headrests, and three with slightly modified commercial headrests. Head and neck injury outcomes measures included: linear head acceleration, head injury criteria (HIC) values, neck injury criteria (N(ij)) values, and combined rotational head velocity and acceleration. Neck and head injury outcome measures improved by 34-70% in sled tests conducted with headrests compared to tests without headrests. Headrest use reduced N(ij) values and the likelihood of concussion from values above established injury thresholds to values below injury thresholds. Injury measure outcome reductions suggest lower head and neck injury risks for wheelchair-seated children using wheelchair-mounted headrests as compared to non-headrest users in rear impact. Use of relative comparisons across two test scenarios served to minimize effects of ATD biofidelity limitations.     

Effectiveness of cable barriers,guardrails, and concrete barrier walls in reducing the risk of injury

Roadway departure crashes tend to be severe, especially when the roadside exposes the occupants of errant vehicles to excessive injury hazards. As a cost-effective method when the clear zone width is insufficient, road barriers are often installed to prevent errant vehicles from colliding with dangerous obstacles or traversing steep slopes. This paper focuses on the safety performance of road barriers in Indiana in reducing the risk of injury. The objective of the study presented here is to compare the risk of injury among different hazardous events faced by an occupant in a single-vehicle crash. The studied hazardous events include rolling over, striking three types of barriers (guardrails, concrete barrier walls, and cable barriers) with different barrier offsets to the edge of the travelled way, and striking various roadside objects.     

Analysis of bolted joints in composite laminates: Strains and bearing stiffness predictions

A review of the investigations conducted on mechanically fastened joints is presented. A finite-element model is developed to predict the response of pin-loaded composite plates. The model takes into account contact at the pin–hole interface, progressive damage, large deformation theory, and a nonlinear shear stress–strain relationship. To predict progressive ply failure, four different analyses combining Hashin and the maximum stress failure criteria, and different associated degradation rules are conducted. The objectives of the study are to determine the influence of the failure criteria and the associated degradation rules on the predictions of the strains around the hole and the bearing stiffness. Predictions are compared with experimental results. It appears that agreement between the two depends on an appropriate selection of the failure criterion and the degradation rule. Better agreement between experimental results and numerical predictions is observed with the maximum stress criterion.     

Construction and evaluation of thoracic injury risk curves for a finite element human body model in frontal car crashes

There is a need to improve the protection to the thorax of occupants in frontal car crashes. Finite element human body models are a more detailed representation of humans than anthropomorphic test devices (ATDs). On the other hand, there is no clear consensus on the injury criteria and the thresholds to use with finite element human body models to predict rib fractures. The objective of this study was to establish a set of injury risk curves to predict rib fractures using a modified Total HUman Model for Safety (THUMS). Injury criteria at the global, structural and material levels were computed with a modified THUMS in matched Post Mortem Human Subjects (PMHSs) tests. Finally, the quality of each injury risk curve was determined. For the included PMHS tests and the modified THUMS, DcTHOR and shear stress were the criteria at the global and material levels that reached an acceptable quality. The injury risk curves at the structural level did not reach an acceptable quality.     

Head injury prediction capability of the HIC, HIP, SIMon and ULP criteria

The objective of the present study is to synthesize and investigate using the same set of sixty-one real-world accidents the human head injury prediction capability of the head injury criterion (HIC) and the head impact power (HIP) based criterion as well as the injury mechanisms related criteria provided by the simulated injury monitor (SIMon) and the Louis Pasteur University (ULP) finite element head models. Each accident has been classified according to whether neurological injuries, subdural haematoma and skull fractures were reported. Furthermore, the accidents were reconstructed experimentally or numerically in order to provide loading conditions such as acceleration fields of the head or initial head impact conditions. Finally, thanks to this large statistical population of head trauma cases, injury risk curves were computed and the corresponding regression quality estimators permitted to check the correlation of the injury criteria with the injury occurrences. As different kinds of accidents were used, i.e. footballer, motorcyclist and pedestrian cases, the case-independency could also be checked. As a result, FE head modeling provides essential information on the intracranial mechanical behavior and, therefore, better injury criteria can be computed. It is clearly shown that moderate and severe neurological injuries can only be distinguished with a criterion that is computed using intracranial variables and not with the sole global head acceleration.     

Age and sex differences in the risk of causing vehicle collisions in Spain, 1990 to 1999

This retrospective, paired case-control study was designed to estimate crude and adjusted effects of age and sex on the risk of causing collisions between vehicles with four or more wheels in Spain during the period from 1990 to 1999. We selected all 220284 collisions registered from 1990 to 1999 in the Spanish Dirección General de Tráfico (DGT) traffic crash database in which only one driver committed any infraction. Information was collected about age, sex and several confounding factors for both the responsible and paired-by-collision nonresponsible drivers. Crude and adjusted odds ratios (aORs) were calculated for each age and sex category. For men, the lowest risk was seen for drivers aged 25-49 years. Below the age of 35 years the crude odds ratio (cOR) was highest in the 18-24-year-old group (1.61; CI: 1.57-1.65). The risk increased significantly and exponentially after the age of 50 years, to a maximum odds ratio of 3.71 (3.43-4.00) for drivers aged >74 years. In women, the lowest risk values were found for the 25-44-year-old age group. In older women the risk increased significantly with age to a maximum odds ratio of 3.02 (2.31-3.97) in the oldest age group. aOR estimates tended to be lower than crude estimates for drivers younger than 40 years of age, but the opposite was seen for drivers 40 years old and older. Regarding sex differences, among younger drivers crude and aORs for men were higher than for women. Our results suggest that the risk of causing a collision between vehicles with four or more wheels is directly dependent on the driver's age.     

An investment plan for preventing child injuries using risk priority number of failure mode and effects analysis methodology and a multi-objective, multi-dimensional mixed 0-1 knapsack model

In this paper, a general framework for child injury prevention and a multi-objective, multi-dimensional mixed 0-1 knapsack model were developed to determine the optimal time to introduce preventive measures against child injuries. Furthermore, the model maximises the prevention of injuries with the highest risks for each age period by combining preventive measures and supervision as well as satisfying budget limits and supervision time constraints. The risk factors for each injury, variable, and time period were based on risk priority numbers (RPNs) obtained from failure mode and effects analysis (FMEA) methodology, and these risk factors were incorporated into the model as objective function parameters. A numerical experiment based on several different situations was conducted, revealing that the model provided optimal timing of preventive measures for child injuries based on variables considered.     

Effects of the feeling of invulnerability and the feeling of control on motivation to participate in experience-based analysis,by type of risk

Experience-based analysis (EBA) refers to a set of safety-management practices consisting of detecting, analyzing, and correcting the individual, material, and organizational causal factors of accidents in order to prevent their reoccurrence. Unfortunately, these practices do not always garner the adherence of employees. This article presents a study that examines the impact of risk perceptions on agents’ motivation to participate in EBA in various production sectors. The study was conducted at two sites, a chemical factory and a nuclear power plant, by means of a questionnaire administered to 302 employees. The results indicated that the feeling of control was not only positively linked to the feeling of invulnerability, but that these two factors were negatively linked to risk perception. In addition, the actors in both production sectors were more motivated to participate in EBA of accidents linked to the core processes of their industry (which were more accurately perceived) than in EBA of ordinary accidents (accidents not specific to chemical or nuclear processes). Moreover, the agents’ feeling of invulnerability and feeling of control both reduced EBA motivation for ordinary accidents to a greater extent than for chemical and radiation-related accidents. Recommendations are made in view of encouraging agents to get more involved in EBA.     

Effect of weight,height and BMI on injury outcome in side impact crashes without airbag deployment

A comprehensive analysis is performed to evaluate the effect of weight, height and body mass index (BMI) of occupants on side impact injuries at different body regions. The accident dataset for this study is based on the National Automotive Sampling System-Crashworthiness Data System (NASS-CDS) for accident year 2000–08. The mean BMI values for driver and front passenger are estimated from all types of crashes using NASS database, which clearly indicates that mean BMI has been increasing over the years in the USA. To study the effect of BMI in side impact injuries, BMI was split into three groups namely (1) thin (BMI < 21), (2) normal (BMI 24–27), (3) obese (BMI > 30). For more clear identification of the effect of BMI in side impact injuries, a minimum gap of three BMI is set in between each adjacent BMI groups. Car model years from MY1995–1999 to MY2000–2008 are chosen in order to identify the degree of influence of older and newer generation of cars in side impact injuries. Impact locations particularly side-front (F), side-center (P) and side-distributed (Y) are chosen for this analysis. Direction of force (DOF) considered for both near side and far side occupants are 8 o’clock, 9 o’clock, 10 o’clock and 2 o’clock, 3 o’clock and 4 o’clock respectively. Age <60 years is also one of the constraints imposed on data selection to minimize the effect of bone strength on the occurrence of occupant injuries. AIS2+ and AIS3+ injury risk in all body regions have been plotted for the selected three BMI groups of occupant, delta-V 0–60 kmph, two sets (old and new) of car model years. The analysis is carried with three approaches: (a) injury risk percentage based on simple graphical method with respect to a single variable, (b) injury distribution method where the injuries are marked on the respective anatomical locations and (c) logistic regression, a statistical method, considers all the related variables together. Lower extremity injury risk appears to be high for thin BMI group. It is found that BMI does not have much influence on head injuries but it is influenced more by the height of the occupant. Results of logistic analysis suggest that BMI, height and weight may have significant contribution towards side impact injuries across different body regions.