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Event Data Recorder (EDR) is an additional function installed in airbag control module (ACM) to record vehicle and occupant information for a brief period of time before, during, and after a crash event. EDRs are now being installed in ACMs by several automakers in the USA and in Japan. The aim of this study is to understand the performance of EDRs for the improvement of accident reconstruction with more reliable information. In the first report of the study, data obtained from EDRs of seven vehicle types were evaluated using 2006-2007 J-NCAP (Japanese new car assessment program) full-lap frontal barrier crash tests and offset frontal deformable barrier crash tests data. For more practical standpoint, we conducted thirteen crash tests reconstructing typical real-world accidents such as single vehicle accidents with barriers or poles, car to car accidents and multi rear-end collisions focusing on Japanese typical accident types. Data obtained from EDRs are compared with data obtained from optical speed sensor, instrumented accelerometers and high speed video cameras. The velocities determined from pre-crash data of EDRs and the maximum change in velocity, delta-V, and delta-V time history data obtained from post-crash data of EDRs are analyzed. The results are as follows: - Pre-crash velocities of EDRs were very accurate and reliable. An average difference between the EDR recording values and reference speeds was 4.2% and a root mean square of the differences was 9.2%. Only two cases resulted large differences for the pre-crash velocity. Both of them were cases with braking prior to the collision. However, another test with braking resulted less difference. The braking condition may influence accuracy of pre-crash velocities. - Maximum delta-Vs obtained from the EDRs showed uncertainty of measurement in several cases in comparisons with the reliable delta-V data. The differences in maximum delta-V were more than 10% in five of twenty-five events data and more than 20% in two of twenty-five events data. An average of the all differences was about 4% and root mean square of the differences was about 11%. Especially large deformation at narrow area may influence accuracy of post-crash delta-V. - Multiple rear-end crash tests were reconstructed using EDRs data as case studies. Some EDRs recorded two events and a time gap between two events, so that these reconstruction case studies were very accurate and reliable. - If though only one of three vehicles in multiple rear end crash was equipped EDR, overview and velocities of all cars may be reconstructed using these limited EDR data. In this case study, leading car- EDR data and middle car- EDR data were valuable. However if only following car was equipped EDR, the reconstruction was not accurate
Small overlap frontal crashes are defined by a damage pattern with most of the vehicle deformation concentrated outboard of the main longitudinal structures. These crashes are prominent among frontal crashes resulting in serious and fatal injuries, even among vehicles that perform well in regulatory and consumer information crash tests. One of the critical aspects of understanding these crashes is knowing the crash speeds that cause the types of damage associated with serious injuries. Laboratory crash tests were conducted using 12 vehicles in three small overlap test conditions: pole, vehicle-to-vehicle collinear, and vehicle-to-vehicle oblique (15-degree striking angle). Field reconstruction techniques were used to estimate the delta V for each vehicle, and these results were compared with actual delta V values based on vehicle accelerometer data. Estimated delta Vs were 50% lower than actual values. Velocity change estimates for small overlap frontal crashes in databases such as NASS-CDS significantly underestimate actual values.
Bone fracture patterns could be crucial in reconstructing the nature of loading, especially in the lower limb and upper limb kinematics in vehicle-pedestrian crashes. In addition, use of FE bone models can be a handy tool to predict vehicle impact velocity and the impact direction. The point of fracture initiation in bone loading has been predicted quite accurately earlier. A methodology that predicts bone crack initiation and its propagation pattern for the six known loading directions using a single material and failure model is presented.
Pedestrian and cyclist are the most vulnerable road users in traffic crashes. One important aspect of this study was the comparable analysis of the exact impact configuration and the resulting injury patterns of pedestrians and cyclists in view of epidemiology. The secondary aim was assessment of head injury risks and kinematics of adult pedestrian and cyclists in primary and secondary impacts and to correlate the injuries related to physical parameters like HIC value, 3ms linear acceleration, and discuss the technical parameter with injuries observed in real-world accidents based documented real accidents of GIDAS and explains the head injuries by simulated load and impact conditions based on PC-Crash and MADYMO. A subsample of n=402 pedestrians and n=940 bicyclists from GIDAS database, Germany was used for preselection, from which 22 pedestrian and 18 cyclist accidents were selected for reconstruction by initially using PC-Crash to calculate impact conditions, such as vehicle impact velocity, vehicle kinematic sequence and throw out distance. The impact conditions then were employed to identify the initial conditions in simulation of MADYMO reconstruction. The results show that cyclists always suffer lower injury outcomes for the same accident severity. Differences in HIC, head relative impact velocity, 3ms linear contiguous acceleration, maximum angular velocity and acceleration, contact force, throwing distance and head contact timing are shown. The differences of landing conditions in secondary impacts of pedestrians and cyclists are also identified. Injury risk curves were generated by logistic regression model for each predicting physical parameters.
Recent findings from real-world accident data have shown that fatality risks for pedestrians are substantially lower than generally reported in the traffic safety literature. One of the keys to this insight has been the large and random sample of car-to-pedestrian crashes available in the German In-Depth Accident Study (GIDAS). Another key factor has been the proper use of weight factors in order to adjust for outcome-based sampling bias in the accident data. However, a third factor, a priori of unknown importance, has not yet been properly analysed. This is the influence of errors in impact speed estimation. In this study, we derived a statistical model of the impact speed errors for pedestrian accidents present in the GIDAS database. The error model was then applied to investigate the effect of the estimation error on the pedestrian fatality risk as a function of car impact speed. To this end, we applied a method known as the SIMulation-EXtrapolation (SIMEX) method. It was found that the risk curve is fairly tolerant to some amount of random measurement error, but that it does become flattened. It is therefore important that the accident investigations and reconstructions are of high quality to assure that systematic errors are minimised and that the random errors are under control.
Accidents involving two wheels vehicles represent one of the more important types of accidents in Europe. These accidents are usually not easy to reconstruct specially for the analysis of the injuries and its correlation with accident dynamics and evidences. Different methodologies are applied in this work for the reconstruction of two wheeler accidents, especially accident involving motorcycles. From the typologies of road evidences like skid marks, to the use of Pc-Crash and the use of Madymo models, different reconstruction of real accidents are presented. One of the questions that sometimes arise for legal purposes when some type of head injuries arise is if the occupant was wearing or not a helmet. The correlation of head injuries with the use of the helmet is a very important issue, therefore an important legal aspect. One of the key questions for the reconstructions that is difficult to analyze, is if the vehicle occupant, was or not, wearing the helmet. Based on the previously collected information, a generic model of a helmet was developed on CAD 3D, followed by its conversion into finite elements, all in order to perform impact tests using the Madymo software that would help improve the helmet- safety, but that also can be used as a tool in accident reconstruction.