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Injury probability functions for pedestrians and bicyclists based on real-world accident data
(2017)
The paper is focusing on the modelling of injury severity probabilities, often called as Injury Risk Functions (IRF). These are mathematical functions describing the probability for a defined population and for possible explanatory factors (variables) to sustain a certain injury severity. Injury risk functions are becoming more and more important as basis for the assessment of automotive safety systems. They contribute to the understanding of injury mechanisms, (prospective) evaluation of safety systems and definition of protection criteria or are used within regulation and/or consumer ratings. In all cases, knowledge about the correlation between mechanical behavior and injury severity is needed. IRFs are often based on biomechanical data. This paper is focusing on the derivation of injury probability models from real world accident data of the GIDAS database (German In-depth Accident Study). In contrast to most academic terms there is no explicit term definition or definition of creation processes existing for injury probability models based on empirical data. Different approaches are existing for such kind of models in the field of accident research. There is a need for harmonization in terms of the used methods and data as well as the handling with the existing challenges. These are preparation of the dataset, model assumptions, censored/unknown data, evaluation of model accuracy, definition of dependent and independent variable, and others. In the presented study, several empirical, statistical and phenomenological approaches were analyzed regarding their advantages and disadvantages and also their applicability. Furthermore, the identification of appropriate prediction parameters for the injury severity of pedestrians has been considered. Due to its main effect on injuries of pedestrians and bicyclists, the importance of the secondary impact has also been analyzed. Finally, the model accuracy, evaluated by several criteria, is the rating factor that gives the quality and reliability for application of the resulting models. After the investigation and evaluation of statistical approaches one method was chosen and appropriate prediction variables were examined. Finally, all findings were summarized and injury risk functions for pedestrians in real world accidents were created. Additionally, the paper gives instructions for the interpretation and usage of such functions. The presented results include IRFs for several injury severity levels and age groups. The presented models are based on a high amount of real world accidents and describe very well the injury severity probability of pedestrians and bicyclists in frontal collisions with current vehicles. The functions can serve as basis for the evaluation of effectiveness of systems like Pedestrian-AEB or Bicycle-AEB.
In most of developed countries, the progress made in passive safety during the last three decades allowed to drastically reduce the number of killed and severely injured especially for occupants of passenger cars. This reduction is mainly observed for frontal impacts for which the AIS3+ injuries has been reduced about 52% for drivers and 38% for front passengers. The stiffening of the cars' structure coupled with the generalization of airbags and the improvement of the seatbelt restraint (load limiter, pretension, etc.) allowed to protect vital body regions such as head, neck and thorax. However, the abdomen did not take advantage with so much success of this progress. The objective of this study is to draw up an inventory on the abdominal injuries of the belted car occupants involved in frontal impact, to present adapted counter-measures and to assess their potential effectiveness. In the first part the stakes corresponding to the abdominal injuries will be defined according to types of impact, seat location, occupants' age and type of injured organs. Then, we shall focus on the abdominal injury risk curves for adults involved in frontal impact and on the comparisons of the average risks according to the seat location. In the second part we will list counter-measures and we shall calculate their effectiveness. The method of case control will be used in order to estimate odds ratio, comparing two samples, given by occupants having or not having the studied safety system. For this study, two type of data sources are used: national road injured accident census and retrospective in-depth accident data collection. Abdominal injuries are mainly observed in frontal impact (52%). Fatal or severe abdominal occupant- injuries are observed at least in 27% of cases, ranking this body region as the most injured just after the thorax (51%). In spite of a twice lower occupation rate in the back seats compared to the front seats, the number of persons sustaining abdominal injuries at the rear place is higher than in the front place. In recent cars, the risk of having a serious or fatal abdominal injury in a frontal impact is 1.6% for the driver, 3.6% for the front passenger and 6.3% for the rear occupants. The most frequently hurt organs are the small intestine (17%), the spleen (16%) and the liver (13%). The most common countermeasures have a good efficiency in the reduction of the abdominal injuries for the adults: the stiffness of the structure of the seats allows decreasing the abdominal injury risk from 54% (driver) to 60% (front occupant), the seatbelt pretensioners decrease also this risk from 90% (driver) to 83% (front passenger).
Im Rahmen des weltweiten ESV-Programmes (Enhanced Safety of Vehicles) werden seit mehreren Jahren internationale Forschungsbemühungen unternommen (International Harmonized Research Activities, IHRA), um im Vorfeld der Gesetzgebung die wissenschaftlichen Grundlagen gemeinsam zu erarbeiten. Ziel der IHRA-Arbeiten ist es, auf der Grundlage dieser Forschungsergebnisse die Harmonisierung der Vorschriften zu erleichtern. Eine besondere Aktivität bezieht sich auf Intelligent Transportation Systems (ITS). Im vorliegenden Beitrag wird die Aufgabe dieser IHRA-ITS-Arbeiten geschildert, sowie der derzeitige Stand der Forschungsbemühungen beschrieben. Es zeigt sich, dass die beschriebene Sicherheitsbewertung eine Fülle von Fragestellungen aufwirft und weitere Forschungsanstrengungen erfordert. Die zukünftigen Bemühungen sind darauf gerichtet, in internationaler Zusammenarbeit und Arbeitsteilung die als besonders wichtig erkannten Themen zur Bewertung der fahrzeugseitigen Fahrerassistenzsysteme zu bearbeiten.
In the European Project FIMCAR, a proposal for a frontal impact test configuration was developed which included an additional full width deformable barrier (FWDB) test. Motivation for the deformable element was partly to measure structural forces as well as to produce a severe crash pulse different from that in the offset test. The objective of this study was to analyze the safety performance of vehicles in the full width rigid barrier test (FWRB) and in the full width deformable barrier test (FWDB). In total, 12 vehicles were crashed in both configurations. Comparison of these tests to real world accident data was used to identify the crash barrier most representative of real world crashes. For all vehicles, the airbag visible times were later in the FWDB configuration. This was attributed to the attenuation of the initial acceleration peak, observed in FWRB tests, by the addition of the deformable element. These findings were in alignment with airbag triggering times seen in real world crash data. Also, the dummy loadings were slightly worse in FWDB compared to FWRB tests, which is possibly linked to the airbag firing and a more realistic loading of the vehicle crash structures in the FWDB configuration. Evaluations of the lower extremities have shown a general increasing of the tibia index with the crash pulse severity.
EEVC Working Group 15 (Compatibility Between Passenger Cars) has carried out research for several years thanks to collaborative project funded by the E.C. and also by exchanging results of projects funded by national programmes. The main collaborative activity of the EEVC WG15 for the last four years was a research project partly funded by the European Commission, where the group made the first attempt to investigate compatibility between passenger cars in a comprehensive research program. Accident, crash test, and mathematical modelling data were analysed. The main result was that structural incompatibilities were frequently found and identified as the main source of incompatibility problems but were not easy to quantify. Unfortunately as little vehicle information other than mass is recorded in most accident databases, most analyses have only been able to show the effect of mass or mass ratio. Common ideas to improve compatibility have been reached by this group and from discussion with other research groups. They will be investigated in the next phase, where research work will concentrate on the development of methods to assess compatibility of passenger cars. The main idea is that the prerequisite to improve crash compatibility between cars is to improve structural interaction. The most important issue is that improved compatibility must not compromise a vehicle- self protection. Test methods should lead to vehicles which show good structural interaction in car to car accidents. Test methods to prove good compatibility may be an adaptation of existing regulatory test procedures (offset deformable barrier test or full width test like in the USA) for frontal impact or may be new compatibility tests. Additional criteria, e.g. impact force distribution, and maximum vehicle deceleration or maximum vehicle impact force should result in compatible cars. Attempts will be made to estimate the benefit of a more compatible car fleet for the European Community.
This paper provides an overview of the research work of the European Enhanced Vehicle-safety Committee (EEVC) in the field of crash compatibility between passenger cars. Since July 1997 the EC Commission is partly funding the research work of EEVC. The running period of this project will be two years. The progress of five working packages of this research project is presented: Literature review, Accident analysis, Structural survey of cars, Crash testing, and Mathematical modelling. According to the planned time schedule the progress of research work is different for the five working packages.
At the 2001 ESV-Conference the EEVC working group on compatibility (WG 15) reported the first phase of the research work to investigate the major factors influencing compatibility between passenger cars. Following this, WG15 performed an interim study, which was partly subventioned by the European Commission, the results of which are reported in this paper. In the next phase of work, it is intended to complete the development of a suite of test procedures and associated performance criteria to assess the compatibility of passenger cars in frontal impacts The main areas of work for the interim study were: - in depth accident data analysis - the development of methods to assess the potential benefit of improved compatibility - crash testing. The accident analysis identified the major compatibility problems to be poor structural interaction, stiffness mismatching and compartment strength. Different methods to assess the potential benefit of improved compatibility were applied to in depth accident data. Full scale crash testing including a car to car test was performed to help develop the following candidate compatibility test procedures: - a full width wall test with a deformable aluminium honeycomb face and a high resolution load cell wall - an offset barrier test with the EEVC barrier face and a high resolution load cell wall - an offset barrier test with the progressively deformable barrier (PDB) face. The results of the interim study will be presented in detail and the proposed methodology of the next phase to complete the development of a suite of test procedures for the assessment of car to car compatibility in frontal impacts will be outlined
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.
As set out in the Terms of Reference, the objective of European Enhanced Vehicle-safety Committee (EEVC) Working Group (WG) 15 Car Crash Compatibility and Frontal Impact is to develop a test procedure(s) with associated performance criteria for car frontal impact compatibility. This work should lead to improved car to car frontal compatibility and self protection without decreasing the safety in other impact configuration such as impacts with car sides, trucks, and pedestrians. Since 2003, EEVC WG 15 served as a steering group for the car-to-car activities in the "Improvement of Vehicle Crash Compatibility through the development of Crash Test Procedures" (VC-COMPAT) project that was finalised at the end of 2006 and partly funded by the European Commission. This paper presents the research work carried out in the VC-COMPAT project and the results of its assessment by EEVC WG 15. Other additional work presented by the UK and French governments and industry " in particular the European industry - was taken into consideration. It also identifies current issues with candidate testing approaches. The candidate test approaches are: - an offset barrier test with the progressive deformable barrier (PDB) face in combination with a full width rigid barrier test - a full width wall test with a deformable aluminium honeycomb face and a high resolution load cell wall supplemented by the forces measured in the offset deformable barrier (ODB) test with the current EEVC barrier. These candidate test approaches must assess the structural interaction and give information of frontal force levels and compartment strength for passenger vehicles. Further, this paper presents the planned route map of EEVC WG 15 for the evaluation of the proposed test procedures and assessment criteria.