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Test and assessment procedures for passive pedestrian protection based on developments by the European Enhanced Vehicle-safety Committee (EEVC) have been introduced in world-wide regulations and consumer test programmes, with considerable harmonization between these programmes. Nevertheless, latest accident investigations reveal a stagnation of pedestrian fatality numbers on European roads running the risk of not meeting the European Union- goal of halving the number of road fatalities by the year 2020. The branch of external road user safety within the EC-funded research project SENIORS under the HORIZON 2020 framework programme focuses on investigating the benefit of modifications to pedestrian test and assessment procedures and their impactors for vulnerable road users with focus on the elderly. Injury patterns of pedestrians and cyclists derived from the German In-Depth Accident Study (GIDAS) show a trend of AIS 2+ and AIS 3+ injuries getting more relevant for the thorax region in crashes with newer cars (Wisch et al., 2017), while maintaining the relevance for head and lower extremities. Several crash databases from Europe such as GIDAS and the Swedish Traffic Accident Data Acquisition (STRADA) also show that head, thorax and lower extremities are the key affected body regions not only for the average population but in particular for the elderly. Therefore, the SENIORS project is focusing on an improvement of currently available impactors and procedures in terms of biofidelity and injury assessment ability towards a better protection of the affected body regions, incorporating previous results from FP 6 project APROSYS and subsequent studies carried out by BASt. The paper describes the overall methodology to develop revised FE impactor models. Matched human body model and impactor simulations against generic test rigs provide transfer functions that will be used for the derivation of impactor criteria from human injury risk functions for the affected body regions. In a later step, the refined impactors will be validated by simulations against actual vehicle front-ends. Prototyping and adaptation of test and assessment procedures as well as an impact assessment will conclude the work of the project at the final stage. The work will contribute to an improved protection of vulnerable road users focusing on the elderly. The use of advanced human body models to develop applicable assessment criteria for the revised impactors is intended to cope with the paucity of actual biomechanical data focusing on elderly pedestrians. In order to achieve optimized results in the future, the improved test methods need to be implemented within an integrated approach, combining active with passive safety measures. In order to address the developments in road accidents and injury patterns of vulnerable road users, established test and assessment procedures need to be continuously verified and, where needed, to be revised. The demographic change as well as changes in the vehicle fleet, leading to a variation of accident scenarios, injury frequencies and injury patterns of vulnerable road users are addressed by the work provided by the SENIORS project, introducing updated impactors for pedestrian test and assessment procedures.
A legform impactor with biofidelic characteristics (FlexPLI) which is being developed by the Japanese Automobile Research Institute (JARI) is being considered as a test tool for legislation within a proposed Global Technical Regulation on pedestrian protection (UNECE, 2006) and therefore being evaluated by the Technical Evaluation Group (TEG) of GRSP. In previous built levels it already showed good test results on real cars as well as under idealised test conditions but also revealed further need for improvement. A research study at the Federal Highway Research Institute (BASt) deals with the question on how leg injury risks of modern car fronts can be revealed, reflected and assessed by the FlexPLI and how the impactor can be used and implemented as a legislative instrument for the type approval of cars according to current and future legislations on pedestrian protection. The latest impactor built level (GTα ) is being evaluated by a general review and assessment of the certification procedure, the knee joint biofidelity and the currently proposed injury criteria. Furthermore, the usability, robustness and durability as a test tool for legislation is examined and an assessment of leg injuries is made by a series of tests with the FlexPLI on real cars with modern car front shapes as well as under idealised test conditions. Finally, a comparison is made between the FlexPLI and the current european legislation tool, the legform impactor according to EEVC WG 17.
Supported by field accident data and monitoring results of European Regulation (EC) No. 78/2009, recent plans of the European Commission regarding a way forward to improve passive safety of vulnerable road users include, amongst other things, an extension of the head test area. The inclusion of passive cyclist safety is also being considered by Euro NCAP. Although passenger car to cyclist collisions are often severe and have a significant share within the accident statistics, cyclists are neither considered sufficiently in the legislative nor in the consumer ratings tests. Therefore, a test procedure to assess the protection potential of vehicle fronts in a collision with cyclists has been developed within a current research project. For this purpose, the existing pedestrian head impact test procedures were modified in order to include boundary conditions relevant for cyclists as the second big group of vulnerable road users. Based on an in-depth analysis of passenger car to cyclist accidents in Germany the three most representative accident constellations have been initially defined. The development of the test procedure itself was based on corresponding simulations with representative vehicle and bicycle models. In addition to different cyclist heights, reaching from a 6-year-old child to a 95%-male, also four pedal positions were considered. By reconstruction of a real accident the defined simulation parameters could be validated in advance. The conducted accident kinematics analysis shows for a large portion of the constellations an increased head impact area, which can reach beyond the roof leading edge, as well as high average values for head impact velocity and angle. Based on the simulation data obtained for the different vehicle models, cyclist-specific test parameters for impactor tests have been derived, which have been further examined in the course of head and leg impact tests. In order to study the cyclist accident kinematics under real test conditions, different full scale tests with a Polar-II dummy positioned on a bicycle have been conducted. Overall, the tests showed a good correlation with the simulations and support the defined boundary test conditions. Typical accident scenarios and simulations reveal higher head impact locations, angles and velocities. An extended head impact area with modified test parameters will contribute to an improved protection of vulnerable road users including cyclists. However, due to significantly differing impact kinematics and postures between the lower extremities of pedestrians and cyclists, these injuries cannot be addressed by the means of current test tools such as the flexible pedestrian legform impactor FlexPLI. Based on the findings obtained within the project as well as the existing pedestrian protection requirements a cyclist protection test procedure for use in legislation and consumer test programmes has been developed, whose requirements have been transferred into a corresponding test specification. This specification provides common head test boundary conditions for pedestrians and cyclists, whereby the existing requirements are modified and two parallel test procedures are avoided.
A flexible pedestrian legform impactor (FlexPLI) with biofidelic characteristics is aimed to be implemented within global legislation on pedestrian protection. Therefore, it is being evaluated by a technical evaluation group (Flex-TEG) of GRSP with respect to its biofidelity, robustness, durability, usability and protection level (Zander, 2008). Previous studies at the Federal Highway Research Institute (BASt) and other laboratories already showed good progress concerning the general development, but also the need for further improvement and further research in various areas. An overview is provided of the different levels of development and all kinds of evaluation activities of the Flex-TEG, starting with the Polar II full scale pedestrian dummy as its origin and ending up with the latest legform impactor built level GTR that is expected to be finalized by the end of the year 2009. Using the latest built levels as a basis, gaps are revealed that should be closed by future developments, like the usage of an upper body mass (UBM), the validation of the femur loads, injury risk functions for the cruciate knee ligaments and an appropriate certification method. A recent study on an additional upper body mass being applied for the first time to the Flex-GT is used as means of validation of recently proposed modified impact conditions. Therefore, two test series on a modern vehicle front using an impactor with and without upper body mass are compared. A test series with the Flex-GTR will be used to study both the comparability of the impact behavior of the GT and GTR built level as well as the consistency of test results. Recommendations for implementation within legislation on pedestrian protection are made.
A flexible pedestrian legform impactor (FlexPLI) has been evaluated by a Technical Evaluation Group (Flex-TEG) of the Working Party on Passive Safety (GRSP) of the United Nations Economic Commission for Europe (UN-ECE). It will be implemented within phase 2 of the global technical regulation (GTR 9) as well as within a new ECE regulation on pedestrian safety as a test tool for the assessment of lower extremity injuries in lateral vehicle-to-pedestrian accidents (UN-ECE 2010-1, 2010-2 and 2010-3). Due to its biofidelic properties in the knee and tibia section, the FlexPLI is found to having an improved knee and tibia injury assessment ability when being compared to the current legislative test tool, the lower legform impactor developed by the Pedestrian Safety Working Group of the European Enhanced Vehicle-safety Committee (EEVC WG 17). However, due to a lack of biofidelity in terms of kinematics and loadings in the femur part of the FlexPLI, an appropriate assessment of femur injuries is still outstanding. The study described in this paper is aimed to close this gap. Impactor tests with the FlexPLI at different impact heights on three vehicle frontends with Sedan, SUV and FFV shape are performed and compared to tests with a modified FlexPLI with upper body mass. Full scale validation tests using a modified crash test dummy with attached FlexPLI that are carried out for the first time prove the more humanlike responses of the femur section with applied upper body mass. Apart from that they also show that the impact conditions described in the current technical provisions for tests with the FlexPLI don"t necessarily compensate the missing torso mass in terms of knee and tibia loadings either. Therefore it can be concluded that an applied upper body mass will contribute to a more biofidelic overall behavior of the legform and subsequently an improved injury assessment ability of all lower extremity injuries addressed by the FlexPLI. Nevertheless, the validity of the original as well as the modified legform for tests against vehicles with extraordinary high bumpers as well as flat front vehicles still needs to be evaluated in detail. A first clue is given by the application of an additional accelerometer to the legform.
The PDB, BASt and Opel conducted two test series to evaluate possible effects on the results obtained using the EEVC WG17 Lower Legform Impactor as a test tool for the assessment of pedestrian safety. The reproducibility and repeatability of the test results were assessed using six legform impactors while keeping the test parameters constant. In the second series one impactor was used and the test parameters were varied to assess the effects on the readings of the legform. The test parameters were velocity, temperature, relative humidity, the point of first contact regarding the deviation in z-direction and the deviations of the pitch, roll and yaw angle. The tests were performed using an inverse setup, i.e. the legform was hit by a guided linear impactor equipped with a honeycomb deformation element. This setup was chosen to be able to vary each single parameter while avoiding variations of the other test parameters at the same time. The test parameters were varied stronger than allowed in regulatory use in order to determine possible dependencies between the parameters and the readings which were acceleration, bending angle and shear displacement.
Evaluation of the performance of competitive headforms as test tools for interior headform testing
(2009)
The European Research Project APROSYS has evaluated the interior headform test procedure developed by EEVC WG 13, representing the head contact in the car during a lateral impact. One important aspect within this test procedure was the selection of an appropriate impactor. The WG13 procedure currently uses the Free Motion Headform as used within the FMVSS 201. The ACEA 3.5 kg headform used in Phase 1 of the European Directive and the future European Regulation on Pedestrian Protection is still discussed as a possible alternative. This paper reports work performed by the Federal Highway Research Institute (BASt) as a part of the APROSYS Task 1.1.3. The study compares the two headform impactors according to FMVSS and ACEA, in a series of basic tests in order to evaluate their sensitivity towards different impact angles, impact accuracy, the effect of differences to impactors of the same type and the effects of the repeatability and reproducibility of the test results. The test surface consisted of a steel tube covered with PU foam and PVC, representing the car interior to be tested. Despite of the higher mass of the FMH the HIC values of this impactor were generally lower than those of the ACEA headform. The FMH showed a higher repeatability of test results but a high sensitivity on the angle of roll, the spherical ACEA impactor performed better with regards to the reproducibility. In case of the ACEA impactor-, the angle of roll had no influence.
A series of drop tests and vehicle tests with the adult head impactor according to Regulation (EC) 631/2009 and drop tests with the phantom head impactor according to UN Regulation No. 43 have been carried out by the German Federal Highway Research Institute (BASt) on behalf of the German Federal Ministry of Transport, Building and Urban Development (BMVBS). Aim of the test series was to study the injury risk for vulnerable road users, especially pedestrians, in case of being impacted by a motor vehicle in a way described within the European Regulations (EC) 78/2009 and (EC) 631/2009. Furthermore, the applicability of the phantom head drop test described in UN Regulation No. 43 for plastic glazing should be investigated. In total, 30 drop tests, thereof 18 with the adult head impactor and 12 with the phantom head impactor, and 49 vehicle tests with the adult head impactor were carried out on panes of laminated safety glass (VSG), polycarbonate (PC) and laminated polycarbonate (L-PC). The influence of parameters such as the particular material properties, test point locations, fixations, ambient conditions (temperature and impact angle) was investigated in detail. In general, higher values of the Head Injury Criterion (HIC) were observed in tests on polycarbonate glazing. As the HIC is the current criterion for the assessment of head injury risk, polycarbonate glazing has to be seen as more injurious in terms of vulnerable road user protection. In addition, the significantly higher rebound of the head observed in tests with polycarbonate glazing is suspected to lead to higher neck loads and may also cause higher injury risks in secondary impacts of vulnerable road users. However, as in all tests with PC glazing no damage of the panes was observed, the risk of skin cut injuries may be expected to be reduced significantly. The performed test series give no indication for the test procedure prescribed in UN Regulation No. 43 as a methodology to approve glass windscreen not being feasible for polycarbonate glazing, as all PC panes tested fulfilled the UN R 43 requirements. The performance of the windscreen area will not be relevant for vehicle type approval according to the upcoming UN Regulation for pedestrian protection. However, it is recommended that pedestrian protection being considered for plastic windscreens to ensure at least the same level of protection as glass windscreens.
The head impact of pedestrians in the windscreen area shows a high relevance in real-world accidents. Nevertheless, there are neither biomechanical limits nor elaborated testing procedures available. Furthermore, the development of deployable protection systems like pop-up bonnets or external airbags has made faster progress than the corresponding testing methods. New requirements which are currently not considered are taken into account within a research project of BASt and the EC funded APROSYS (Advanced PROtection SYStems) integrated project relating to passive pedestrian protection. Testing procedures for head impact in the windscreen area should address these new boundary conditions. The presented modular procedure combines the advantages of virtual testing, including full-scale multi-body and finite element simulations, as well as hardware testing containing impactor tests based on the existing procedures of EEVC WG 17. To meet the efforts of harmonization in legislation, it refers to the Global Technical Regulation of UNECE (GTR No. 9). The basis for this combined hardware and virtual testing procedure is a robust categorization covering all passenger cars and light commercial vehicles and defining the testing zone including the related kinematics. The virtual testing part supports also the choice of the impact points for the hardware test and determines head impact timing for testing deployable systems. The assessment of the neck rotation angle and sharp edge contact in the rear gap of pop-up bonnets is included. For the demonstration of this procedure, a hardware sedan shaped vehicle was modified by integrating an airbag system. In addition, tests with the Honda Polar-II Dummy were performed for an evaluation of the new testing procedure. Comparing these results, it was concluded that a combination of simulation and updated subsystem tests forms an important step towards enhanced future pedestrian safety systems considering the windscreen area and the deployable systems.