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The European Enhanced Vehicle-safety Committee wants to promote the use of more biofidelic child dummies and biomechanical based tolerance limits in regulatory and consumer testing. This study has investigated the feasibility and potential impact of Q-dummies and new injury criteria for child restraint system assessment in frontal impact. European accident statistics have been reviewed for all ECE-R44 CRS groups. For frontal impact, injury measures are recommended for the head, neck, chest and abdomen. Priority of body segment protection depends on the ECE-R44 group. The Q-dummy family is able to reflect these injuries, because of its biofidelity performance and measurement capabilities for these body segments. Currently, the Q0, Q1, Q1.5, Q3 and Q6 are available representing children of 0, 1, 1.5, 3 and 6 years old. These Q-dummies cover almost all dummy weight groups as defined in ECE-R44. Q10, representing a 10 year-old child, is under development. New child dummy injury criteria are under discussion in EEVC WG12. Therefore, the ECE-R44 criteria are assessed by comparing the existing P-dummies and new Q-dummies in ECE-R44 frontal impact sled tests. In total 300 tests covering 30 CRSs of almost all existing child seat categories are performed by 11 European organizations. From this benchmark study, it is concluded that the performance of the Q-dummy family is good with respect to repeatability of the measurement signals and the durability of the dummies. Applying ECE-R44 criteria, the first impression is that results for P- and Q-dummy are similar. For child seat evaluation the potential merits of the Q-dummy family lie in the extra measurement possibilities of these dummies and in the more biofidelic response.
This study is aimed to investigate the correlations of impact conditions and dynamic responses with the injuries and injury severity of child pedestrians by accident reconstruction. For this purpose, the pedestrian accident cases were selected from Sweden and Germany with detailed information about injuries, accident cars, and accident environment. The selected accident cases were reconstructed using mathematical models of pedestrian and passenger car. The pedestrian models were generated based on the height, weight, and age of the pedestrian involved in accidents. The car models were built up based on the corresponding accident car. The impact speeds in simulations were defined based on the reported data. The calculated physical quantities were analyzed to find the correlation with injury outcomes registered in the accident database. The reconstruction approaches are discussed in terms of data collection, estimating vehicle impact speeds, pedestrian moving speeds and initial posture, secondary ground impact, validity of the mathematical models, as well as impact biomechanics.
The so-called "seat-belt injuries" or "seat-belt syndromes", described as 2-point seat-belt injuries, contain heavy inflection injuries of the lumbal spinal column, combined with heavy abdominal injuries as rupture of the upper intestinal bold or heavy injuries of the upper entrails. With "playing" children in the font of the car, with inappropriate plant of 3-point belts, identical injuries can occur.
The use of proper child restraint systems (CRS) is mandatory for children travelling in cars in most countries of the world. The analysis of the quantity of restrained children shows that more than 90% of the children in Germany are restrained. Looking at the quality of the protection, a large discrepancy between restrained and well protected children can be seen. Two out of three children in Germany are not properly restrained. In addition, considerable difference exists with respect to the technical performance of CRS. For that reason investigations and optimisations on two different topics are necessary: The technical improvement of CRS and the ease of use of CRS. Consideration of the knowledge gained by the comparison of different CRS in crash tests would lead to some improvements of the CRS. But improvement of child safety is not only a technical issue. People should use CRS in the correct way. Misuse and incorrect handling could lead to less safety than correct usage of a poor CRS. For that reason new technical issues are necessary to improve the child safety AND the ease of use. Only the combination of both parts can significantly increase child safety. For the assessment of the safety level of common CRS, frontal and lateral sled tests simulating different severity levels were conducted comparing pairs of CRS which were felt to be good and CRS which were felt to be poor. The safety of some CRS is currently at a high level. All well known products were not damaged in the performed tests. The performance of non-branded CRS was mostly worse than that of the well known products. Although the branded child restraint systems already show a high safety level it is still possible to further improve their technical performance as demonstrated with a baby shell and a harness type CRS.
Since the compulsory use of child restraints for children up to 5 years of age was introduced in 2000, restraint use among younger children has increased significantly. However, the observed rate of child restraint use plateaus at around 50%, and apparently little spillover effect has been found for older children who are not covered by the law. This report examines the restraint use patterns for children who were injured in cars in relation to driver and child passenger characteristics. Univariate and multivariate analyses were conducted to describe the association between the outcome measure (the proper use of restraints for children) and relevant variables. Better ways for parents and caregivers to improve the use of restraints for children are also discussed.
The primary goal of this investigation was to determine the relative risk of traffic accidents in students. In a two year period, a survey amongst 2,325 students was carried out, and 3,645 injuries sustained by students treated at our hospital were analyzed. Moped-riding in adolescents were associated with a 23.75-fold increased risk for injury as compared to biking. Children who ride bicycles have a 2.2-fold increased risk for an injury sustained by traffic accidents compared to pedestrians. None of 50 injured bicycle riders with helmet had an AIS for head injuries of more than 2. 24 of 233 injured bicycle drivers without helmet had an AIS for head injuries of more than 2. The use of a protective helmet significantly reduced the severity of head injuries. The level of awareness towards danger and a history of previous accidents correlate with the likelihood of future accidents. Due to the severity of traffic accidents, more adequate prevention measures (wearing of bicycle helmets and better education for moped riders) are urgently needed.
Validation of human pedestrian models using laboratory data as well as accident reconstruction
(2007)
Human pedestrian models have been developed and improved continually. This paper shows the latest stage in development and validation of the multibody pedestrian model released with MADYMO. The biofidelity of the multibody pedestrian model has been verified using a range of full pedestrian-vehicle impact tests with a large range in body sizes (16 male, 2 female, standing height 160-192cm, weight 53.5-90kg). The simulation results were objectively correlated to experimental data. Overall, the model predicted the measured response well. In particular the head impact locations were accurately predicted, indicated by global correlation scores over 90%. The correlation score for the bumper forces and accelerations of various body parts was lower (47-64%), which was largely attributed to the limited information available on the vehicle contact characteristics (stiffness, damping, deformation). Also, the effects of the large range in published leg fracture tolerances on the predicted risk to leg fracture by the pedestrian model were evaluated and compared with experimental results. The validated mid-size male model was scaled to a range of body sizes, including children and a female. Typical applications for the pedestrian models are trend studies to evaluate vehicle front ends and accident reconstructions. Results obtained in several studies show that the pedestrian models match pedestrian throw distances and impact locations observed in real accidents. Larger sets of well documented cases can be used to further validate the models especially for specific populations as for instance children. In addition, these cases will be needed to evaluate the injury predictive capability of human models. Ongoing developments include a so-called facet pedestrian model with a more accurate geometry description and a more humanlike spine and neck and a full FE model allowing more detailed injury analysis.
This study examines the severity and types of injuries sustained by child pedestrians aged 18 years and below in order to identify the body regions at greatest risk for injury in a pedestrian accident. Detailed medical diagnoses were reviewed retrospectively for 572 child pedestrians admitted to an urban pediatric trauma center with injuries during the time period from January 2001 to December 2005. Eighty percent of these children sustained AIS 2 or greater injuries, most commonly to the lower extremity (41%) and head (34%). Fortyfour percent of admitted children had more significant AIS 3 or greater injuries primarily to the head (58%), thorax (17%) and lower extremities (14%). Testing procedures to assess the child- interaction with the motor vehicle should include injury assessment for the pediatric head, thorax and lower extremities. This understanding of how child pedestrians interact with motor vehicles may provide insight into effective countermeasures with potential for implementation in vehicle designs world-wide.
Within the process of integrating passenger airbags in the vehicle fleet a problem of compatibility between the passenger airbag and rear-facing child restraint systems was recognised. Especially in the US several accidents with children killed by the passenger airbag were recorded. Taking into account these accidents the deactivation of a present passenger airbag is mandatory if a child is carried in a rear-facing child restraint system at the front passenger seat in all member states of the European Union. This rule is in force since the deadline of 2003/20/EC at the latest. In the past a passenger airbag either could not be disabled or could only be disabled by a garage. Today there are a lot of different possibilities for the car driver himself to disable the airbag. Solutions like an on/off-switch or the automatic detection of a child restraint system are mentioned as an example. Taking into account the need for the deactivation of front passenger airbags two types of misuse can occur: transportation of an infant while the airbag is (still) enabled and transportation of an adult, while the airbag is disabled, respectively. Within a research project funded by BASt both options of misuse were analysed utilising two different types of surveys amongst users (field observations and interviews, Internet-questionnaires). In addition both analysis of accident data and crash tests for an updated assessment of the injury risk caused by the front passenger airbag were conducted. Both surveys indicate a low risk of misuse. Most of the misuse cases were observed in older cars, which offer no easy way to disable the airbag. For systems, which detect a child seat automatically, no misuse could be found. The majority of misuses in cars equipped with a manual switch were caused by reasons of oblivion. Also the accident analysis indicates a minor risk of misuse. From more than 300 cases of the GIDAS accident sample that were analysed, only 24 children were using the front passenger seat in cars equipped with a front passenger airbag. In most of these cases the airbag was deactivated. When misuse occurred the injury severity was low. However, when analysing German single accidents the fatality risk caused by the front passenger airbag became obvious. From the technical point of view, there were important changes in the design of passenger airbags in recent years. Not only volume and shape were modified, but also the mounting position of the entire airbag module was changed fundamentally. Even if these findings do not allow obtaining general conclusions, a clear tendency of less danger by airbags could be identified. For future vehicle development a safe combination of airbags and rear faced baby seats seems to be possible in the long term. This would mean that both types of misuse could be eliminated. For parents an easier use of child seat and car would be the result.
According to the German road traffic regulations children up to the age of 12 or a height below 150 cm have to use approved and appropriate child restraint systems (CRS). CRS must be approved according to UN-ECE Regulation No. 44. The regulation classifies CRS in 5 weight categories. The upper weight group is approved for children from 22 to 36 kg. However, studies show that already today many children weigh more than 36 kg although they have not reached a height of 150 cm. Therefore, no ECE R44 approved CRS is available for these overweight children. In conclusion, today's sizes and weights of children are no longer represented by the current version of the ECE R44. The heaviest used dummy (P10) weighs just 32.6 kg and has a height of 137.9 cm. Statistical data of German children show that already 5% of the children at a height of 137.9 cm have a weight above 45.3 kg. Regarding children at a height of 145 cm, the 95th percentile limit is at a weight of 53.3 kg. Based on these data 4 dummies with different heights and weights were defined and produced. Two of them are overweight. Up to now, there is no experience how current child restraint systems perform in a car crash if they are used by children with a weight above 36 kg and a height smaller than 150 cm. In the future, different child restraint systems will be tested with respect to the ECE R44 regulation using these overweight dummies.