Pedestrian Kinematics Research Articles

Injury patterns in motor vehicle collision–youth pedestrian deaths

Objective The objective of this study was to describe fatal pedestrian injury patterns in youth aged 15 to 24 years old and correlate them with motor vehicle collision (MVC) dynamics and pedestrian kinematics using data from medicolegal death investigations of MVCs occurring in the current Canadian motor vehicle (MV) fleet. Methods Based on a systematic literature review, MVC–pedestrian injuries were collated in an injury data collection form (IDCF). The IDCF was coded using the Abbreviated Injury Scale (AIS) 2015 revision. The AIS of the most frequent severe injury was noted for individual body regions. The Maximum AIS (MAIS) was used to define the most severe injury to the body overall and by body regions (MAISBR). This study focused on serious to maximal injuries (AIS 3–6) that had an increasing likelihood of causing death. The IDCF was used to extract collision and injury data from the Office of the Chief Coroner for Ontario (OCCO) database of postmortem examinations done at the Provincial Forensic Pathology Unit (PFPU) in Toronto, Canada, and other provincial facilities between 2013 and 2019. Injury data were correlated with data about the MVs and MV dynamics and pedestrian kinematics. The study was approved by the Western University Health Science Research Ethics Board (Project ID: 113440; Lawson Health Research Institute Approval No. R-19-066). Results There were 88 youth, including 54 (61.4%) males and 34 (38.6%) females. Youth pedestrians comprised 13.1% (88/670) of all autopsied pedestrians. Cars (n = 25/88, 28.4%) were the most frequent type of vehicle in single-vehicle impacts, but collectively vehicles with high hood edges (i.e., greater distance between the ground and hood edge) were in the majority. Forward projection (n = 34/88, 38.6%) was the most frequent type of pedestrian kinematics. Regardless of the type of vehicle, there was a tendency in most cases for the median MAISBR ≥ 3 to involve the head and thorax. A similar trend was seen in most of the pedestrian kinematics involving the various frontal impacts. Of the 88 cases, at least 63 (71.6%) were known to be engaged in risk-taking behaviors (e.g., activity on roadway). At least 12 deaths were nonaccidental (8 suicides and 4 homicides). Some activities may have been impairment related, because 26/63 (41.3%) pedestrians undertaking risk-taking behavior on the roadway were impaired. Toxicological analyses revealed that over half of the cases (47/88, 53.4%) tested positive for a drug that could have affected behavior. Ethanol was the most common. Thirty-one had positive blood results. Conclusion A fatal dyad of head and thorax trauma was observed for pedestrians struck by cars. For those pedestrians hit by vehicles with high hood edges, which were involved in the majority of cases, a fatal triad of injuries to the head, thorax, and abdomen/retroperitoneum was observed. Most deaths occurred from frontal collisions and at speeds more than 35 km/h.

Effects of the windshield inclination angle on head/brain injuries in car-to-pedestrian collisions using computational biomechanics models

Abstract Car-to-pedestrian collision (CPC) accidents occur frequently, and pedestrians often suffer serious head/brain injuries. One major cause is the primary impact with the windshield. Here, we use a numerical simulation method to study the influence of the windshield inclination angle of a passenger car on pedestrian head/brain injury due to CPC accidents. The range of the windshield inclination angle was set at 24°–50°, with an interval of 2°. The results show that the windshield angle significantly affects the pedestrian kinematics and exerts different effects on the head injury when evaluating with various head injury criteria. Regarding the head peak linear/rotational acceleration and acceleration-based head injury criterion (HIC)/rotational injury criterion (RIC), the predictions at the secondary impact stage have no clear relationship with the windshield angle (R2=0.04, 0.07, 0.03 and 0.26, respectively) and their distributions are scattered. In the primary impact, the peak linear acceleration and HIC show a weak trend of first decreasing and then increasing with the increasing of the windshield angle, and the rotational acceleration and RIC tend to remain relatively constant. Regarding the cumulative strain damage measure (CSDM) criterion, the predictions at the primary impact are slightly lower than those at the secondary impact, and the trend of first decreasing and then increasing with the increase in the windshield angle is observed at both impact stages. When the windshield inclination angle is approximately 32°–40°, the head injury severity in both impact phases is generally lower than that predicted at other windshield angles.

Injury patterns in motor vehicle collision-pediatric pedestrian deaths

Objective To describe fatal pediatric pedestrian injury patterns and correlate them with motor vehicle collision (MVC) characteristics and pedestrian kinematics using data from medicolegal death investigations of MVCs occurring in the current Canadian MV fleet and determine the applicability of the classical “Waddell’s triad” comprising knee, hip (femur) or pelvis and craniocerebral injuries to present data injury patterns. Methods An Injury Data Collection Form was used to extract MV, MVC, pedestrian demographic and injury information from the Office of the Chief Coroner for Ontario database using autopsy data from 2013 to 2018. Injuries were coded using the Abbreviated Injury Scale (AIS) 2015 revision. The study focused on AIS ≥3 injuries utilizing the Maximum Abbreviated Injury Scale (MAIS), MAIS by Body Region (MAISBR) and Injury Severity Score (ISS). Results Between 2013 and 2018, there were 25 pediatric deaths. The pedestrians were either struck and run over (n = 17, 68%; 56% low speed) or struck and projected (n = 8, 32%). Twenty-two deaths were from frontal impacts; three were from reversing vehicles. Fourteen of the 17 (82.4%) run over cases occurred at low speed (<30 km/h). In 9 (36%) cases, the vehicle was turning at impact (right n = 3, left n = 6). A majority of the vehicles had a high hood edge. The head was the most severely injured (median MAISBR = 5 overall and ≤10 years; median MAISBR = 6 for 11–14 years old) followed by the neck (MAISBR = 3 overall; 6–14 years old), and the thorax (median MAISBR = 3 overall; all age groups). For the early adolescents (11-14 years old), the serious injury pattern included the abdomen (median MAISBR = 3.5). Nearly half (n = 11, 44%) sustained brainstem injuries. Over fifty percent of the 16 cases with neck injuries (n = 9, 56.3%) had atlanto-occipital or axial dislocation. Conclusion More than half of the deaths occurred during low speed run overs. MAIS ≥3 injuries trended to a dyad of head and thorax in ≤5 years old, a triad of head, neck, and thorax injuries in children 6–10 years old and a tetrad with the addition of abdominal injuries in pedestrians ≥11 years old. Waddell’s triad was not applicable to the fatal cases in the present study.

Pedestrian Head Impact Analysis on a Vehicle and Measures to Reduce HIC Value

Throughout the world numerous people are killed in vehicle collisions. Different innovations for expanding the energy-engrossing characteristics of the vehicle body are being considered. This paper worked out on the analysis of pedestrian head impact behavior on a vehicle and technique to reduce HIC (Head Impact Criteria) value. Objectives of this research work are: (a) to reduce the HIC (Head injury Criteria) less than 1000 without affecting the outer design and aesthetics of the vehicle, and (b) to find out the best and economical technologies among “rear-rising hood” and “airbag system for controlling pedestrian collision kinematics” to suit Indian requirements. The pedestrian air bag system along with the rear rising hood system is the best possible solution to protect the pedestrian from fatal injuries. The air bag covers the critical areas of the car for better safety.

Pedestrian motion centroid model based on robot dynamics

In recent years, with the rapid development of computer vision technology, image-based human body research has become an important task, such as pedestrian target detection, trajectory tracking, posture estimation and behaviour recognition. The centre of mass is one of the important characteristics that can reflect the phenomenon of pedestrian movement. This paper first introduces the biped robot model in robotics, starting from forward and inverse kinematics, to find the mapping relationship between the position of each joint and the pose of the end effector. Then, corresponding to the skeleton model of the human joint points, the characteristics of the bone posture and joint angle are determined. The moment of inertia factor is introduced, and the motion superposition of different joint points is considered to establish a pedestrian motion centroid model. By calculating the equivalent dynamic centroid, the pedestrian kinematics law can be explored and the pedestrian movement mechanism can be more deeply recognized.

Pedestrian dynamic response and injury risk in high speed vehicle crashes

Purpose The purpose of the current study is to understand pedestrian kinematics, biomechanical response and injury risk in high speed vehicle crashes. Methods Vehicle-to-pedestrian crashes at the impact speeds of 40km/h (reference set) and 70km/h (analysis set) were simulated employing FE models of a sedan front and an SUV front together with a pedestrian FE model developed using hollow structures. The predictions from crash simulations of different vehicle types and impact speeds were compared and analyzed. Results In crashes at 70km/h, pedestrian head-vehicle contact velocity is about 20-30% higher than the vehicle impact speed; the peak head angular velocity exceeds 100rad/s and is close to the instant of head-vehicle contact; brain strain appears two peaks and the second peak (after head contact) is obviously higher than the first (before head contact), and AIS4+ head injury risk is above 50%; excessive thorax compression induces rib fractures and lung compression; both sedan and SUV cases show a high risk (&gt; 70%) of AIS3+ thorax injury, and the risk of AIS4+ thorax injury is lower than 40% in the sedan case and higher than 50% for the SUV case. Conclusions Pedestrians in vehicle crashes at 70km/h have a higher AIS3+/AIS4+ head and thorax injury risk, high vehicle impact speed is more easily to induce a high head angular velocity at the instant of head-vehicle contact, brain strain is strongly associated with the combined effect of head rotational velocity and acceleration, and pedestrian thorax injury risk is more sensitive to vehicle impact speed than the head.

Realistic Reference for Evaluation of Vehicle Safety Focusing on Pedestrian Head Protection Observed From Kinematic Reconstruction of Real-World Collisions.

Head-to-vehicle contact boundary condition and criteria and corresponding thresholds of head injuries are crucial in evaluation of vehicle safety performance for pedestrian protection, which need a constantly updated understanding of pedestrian head kinematic response and injury risk in real-world collisions. Thus, the purpose of the current study is to investigate the characteristics of pedestrian head-to-vehicle contact boundary condition and pedestrian AIS3+ (Abbreviated Injury Scale) head injury risk as functions of kinematic-based criteria, including HIC (Head Injury Criterion), HIP (Head Impact Power), GAMBIT (Generalized Acceleration Model for Brain Injury Threshold), RIC (Rotational Injury Criterion), and BrIC (Brain Injury Criteria), in real-world collisions. To achieve this, 57 vehicle-to-pedestrian collision cases were employed, and a multi-body modeling approach was applied to reconstruct pedestrian kinematics in these real-world collisions. The results show that head-to-windscreen contacts are dominant in pedestrian collisions of the analysis sample and that head WAD (Wrap Around Distance) floats from 1.5 to 2.3 m, with a mean value of 1.84 m; 80% of cases have a head linear contact velocity below 45 km/h or an angular contact velocity less than 40 rad/s; pedestrian head linear contact velocity is on average 83 ± 23% of the vehicle impact velocity, while the head angular contact velocity (in rad/s) is on average 75 ± 25% of the vehicle impact velocity in km/h; 77% of cases have a head contact time in the range 50–140 ms, and negative and positive linear correlations are observed for the relationships between pedestrian head contact time and WAD/height ratio and vehicle impact velocity, respectively; 70% of cases have a head contact angle floating from 40° to 70°, with an average value of 53°; the pedestrian head contact angles on windscreens (average = 48°) are significantly lower than those on bonnets (average = 60°); the predicted thresholds of HIC, HIP, GAMBIT, RIC, BrIC2011, and BrIC2013 for a 50% probability of AIS3+ head injury risk are 1,300, 60 kW, 0.74, 1,470 × 104, 0.56, and 0.57, respectively. The findings of the current work could provide realistic reference for evaluation of vehicle safety performance focusing on pedestrian protection.

The Influence of Gait Stance and Vehicle Type on Pedestrian Kinematics and Injury Risk.

Pedestrians are one of the most vulnerable road users. In 2019, the USA reported the highest number of pedestrian fatalities number in nearly three decades. To better protect pedestrians in car-to-pedestrian collisions (CPC), pedestrian biomechanics must be better investigated. The pre-impact conditions of CPCs vary significantly in terms of the characteristics of vehicles (e.g., front-end geometry, stiffness, etc.) and pedestrians (e.g., anthropometry, posture, etc.). The influence of pedestrian gait posture has not been well analyzed. The purpose of this study was to numerically investigate the changes in pedestrian kinematics and injuries across various gait postures in two different vehicle impacts. Five finite element (FE) human body models, that represent the 50th percentile male in gait cycle, were developed and used to perform CPC simulations with two generic vehicle FE models representing a low-profile vehicle and a high-profile vehicle. In the impacts with the high-profile vehicle, a sport utility vehicle, the pedestrian models usually slide above the bonnet leading edge and report shorter wrap around distances than in the impacts with a low-profile vehicle, a family car/sedan (FCR). The pedestrian postures influenced the postimpact rotation of the pedestrian and consequently, the impacted head region. Pedestrian posture also influenced the risk of injuries in the lower and upper extremities. Higher bone bending moments were observed in the stance phase posture compared to the swing phase. The findings of this study should be taken into consideration when examining pedestrian protection protocols. In addition, the results of this study can be used to improve the design of active safety systems used to protect pedestrians in collisions.

Fatal Motor Vehicle-Pedestrian Collision Injury Patterns-A Systematic Literature Review.

Injury patterns in pedestrians struck by motor vehicles were described in medical literature first published almost a half century ago. "Classical" triads of injury distribution were described for adults (skull-pelvis-extremity) and subsequently applied to children (head-hip or pelvis-distal femur/knee joint). Notably, these classical triads were derived from two publications reporting clinical observations of only 11 patients, all of whom were adults. A systematic literature review was conducted using Medline, CINAHL, EMBASE, and Cochrane to determine the evidence-base for motor vehicle collision (MVC)-pedestrian injury "triads" and other trauma patterns described for pedestrians in the adult and pediatric age groups. Of the 1540 full-text articles identified in the review, 56 articles published in English met the inclusion criteria, that is, motor vehicle-pedestrian collision resulting in specific, fatal injuries determined by postmortem examinations. There were variations in injury patterns that differed from the "classical" triads. These differences likely stem from advances in vehicle design and safety features which have affected the nature and distribution of injuries. Further research on the correlation of specific injuries sustained by pedestrians of different ages with various types of vehicles and impacts are needed to assess the validity of previously observed injury patterns in relation to the current motor vehicle fleet. Delineation of injury patterns can assist health care teams in trauma management. Vehicle manufacturers and government regulators can better assess whether the introduction of advanced driver assistance features designed to protect pedestrians when struck will be effective in reducing severe injuries. In forensic pathology practice, knowledge of pedestrian injury patterns based on data representative of impacts involving modern vehicles can provide MVC death investigators the means to determine MVC dynamics and pedestrian kinematics.

Obesity effects on pedestrian lower extremity injuries in vehicle-to-pedestrian impacts: A numerical investigation using human body models

Objective The objectives of this study were to develop a method for modeling obese pedestrians and to investigate effects of obesity on pedestrian impact responses and injury outcomes. Methods The GHBMC (Global Human Body Model Consortium) 50th percentile male pedestrian model was morphed into geometries with 4 body mass index (BMI) levels (25/30/35/40 kg/m2) predicted by statistical body shape models. Each of the 4 morphed models was further morphed from a standing posture into 2 other gaits (toe-off and mid-swing), which resulted in a total of 12 (4 BMIs × 3 postures) models. Each model was used to simulate vehicle-to-pedestrian impact under 2 impact velocities. Pedestrian kinematics and injury measures were analyzed focusing on lower extremities. Statistical analyses were performed to examine significance of obesity on concerned injury measures. Results Peak values of the bending moment at tibia, force at medial collateral ligament (MCL), bending angle at knee joint, and contact force between vehicle and pedestrian increased significantly (P < .05) with increased BMI. By analyzing kinematics of the lower extremity, the overall vehicle-to-pedestrian impact was divided into 2 phases: “initial contact” and “tibia rebound.” For obese pedestrians, the added mass caused a higher tibia bending moment in the initial contact phase, and the greater moment of inertia led to greater bending angle and MCL force in the tibia rebound phase. Statistical analyses also revealed that pre-impact posture and impact velocity had significant effects on all injury measures. Conclusions Obesity could significantly increase the risk of pedestrian lower extremity injuries due to the inertial effect from the added mass. Pre-impact posture and impact velocity also significantly affect pedestrian injury measures. Future vehicle designs for pedestrian protection should consider populations with obesity. This study demonstrated the feasibility of using parametric human modeling to account for population diversity in injury prediction.

Finite element reconstruction of a vehicle-to-pedestrian impact

Objective This study aims to reconstruct a real-world Crash Injury Research and Engineering Network vehicle-to-pedestrian impact to supplement the determination of pedestrian kinematics and injury causation. Methods A case involving a 46-year-old male pedestrian with a height of 163 cm and mass of 100 kg that was impacted by a 2019 Dodge Charger Pursuit police cruiser at an approximate velocity of 20.1 m/s was reconstructed. The case vehicle was represented by a rigid shell of a 2019 Dodge Charger vehicle exterior from an open-source database. The case pedestrian was represented by the Global Human Body Models Consortium (GHBMC) 50th percentile male simplified pedestrian human body model. The GHBMC model was isometrically scaled to a height of 163 cm and the external layer of flesh was morphed to a male reference geometry with the same age, height, and body mass index as the case pedestrian. The approximate location and position of the pedestrian at the time of impact was determined from case vehicle dashboard camera images and the pedestrian model was adjusted accordingly. Results Reconstruction kinematics aligned with proposed CIREN case kinematics. The GHBMC model predicted fractures of the left inferior ischiopubic ramus, superior pubic ramus, ilium, sacral ala, acetabulum, and right ilium. Conclusions Finite element reconstructions of real-world pedestrian impacts are useful for analyzing pedestrian kinematics and provide an effective tool for improving pedestrian impact injury analyses.

Prediction of pedestrian brain injury due to vehicle impact using computational biomechanics models: Are head-only models sufficient?

Objectives: Accident reconstruction using computational biomechanics models plays an important role in research and prevention of human brain injury caused by car-to-pedestrian impacts. Finite element (FE) “head-only” models (that represent only the pedestrian head and brain) used in such reconstruction do not account for the influence of the rest of the pedestrian body on the head kinematics due to the accident and, consequently, on the brain injury risk prediction. Application of full-scale FE pedestrian models, on the other hand, is limited by their high computational cost and, more importantly, by the time-consuming preprocessing when repositioning the model to represent the pedestrian posture and location in relation to the impacting car. The objective of this study is to propose a computational biomechanics modeling approach to overcome these challenges.Methods: First, we couple a validated commercial FE head-neck complex model and a multibody (MB) pedestrian model. This coupled FE-MB model is evaluated through application in reconstruction of a real-world car-to-pedestrian impact accident and comparison of the pedestrian kinematics predicted using this model with the results obtained from the established full-scale MB pedestrian model. Finally, we compare the results obtained using the coupled FE-MB model proposed in this study and FE head-only model in terms of both the head kinematics and brain injury risk predicted using the two models.Results: The results of analysis of head injury criterion (HIC15) and brain deformation-based injury criteria (instantaneous value of cumulative strain damage measure iCSDM and maximum shear strain of the brain tissue) indicate substantial differences in the head kinematics and brain injury risk predicted using the two models. The coupled FE-MB model predicts a high risk of the brain injury which is consistent with the database record of the analyzed accident, in particular for the impact between the pedestrian head and road surface. In contrast, the head-only model did not predict that such impact can occur. The FE head head-only model with rigid skull and prescribed acceleration–time history of the head center of gravity determined from accident reconstruction using the purely MB pedestrian model, predicted appreciably lower iCSDM than the coupled FE-MB model that accounts for skull deformations using the linear elastic-plastic material model.Conclusions: This study suggests that the FE head-only models may be deficient for car-to-pedestrian impact accident reconstruction and estimation of risk of the pedestrian brain injury. In particular, this applies to the models that simplify the pedestrian skull as a rigid body.

Potential benefits of controlled vehicle braking to reduce pedestrian ground contact injuries

Protecting struck pedestrians during the ground contact phase has been a challenge for decades. Recent studies have shown how ground related injury is influenced by pedestrian kinematics. In this paper we further developed this approach by assessing the potential of controlling vehicle braking to reduce pedestrian ground contact injuries. Applying a recently proposed Simulation Test Sample, a series of simulations were run using the MADYMO software environment. The approach considered 6 vehicle shapes, 4 pedestrian models, 3 impact velocities and 2 pedestrian gaits and each case was considered with two different vehicle braking approaches. The first was full braking, while the second applied controlled braking, for which a strategy based on pedestrian kinematics was applied. The effect of vehicle braking was evaluated using the Weighted Injury Cost (WIC) of overall pedestrian injuries and the pedestrian-ground impact velocity change. The proximity of the vehicle and pedestrian at the instant of ground contact was also evaluated to assess the potential of future vehicle based intervention methods to cushion the ground contact. Finally real-world videos of pedestrian collisions were analyzed to estimate the available free vehicle stopping distances. Results showed substantial median reductions in WIC and head impact velocity for all vehicle shapes except the Van. The proximity of the pedestrian to the vehicle front at the instant of ground contact under controlled braking is less than 1.5 m in most cases, and the required stopping distance for the vehicle under controlled braking was within the available stopping distance estimated from the video footage in about 74% of cases. It is concluded that controlled braking has significant potential to reduce the overall burden of pedestrian ground contact injuries, but future efforts are required to establish an optimized braking strategy as well as a means to handle those cases where controlled braking is not beneficial or even harmful.

PEDESTRIAN SAFETY: A NEW METHOD TO ASSESS PEDESTRIAN KINEMATICS

The progress in pedestrian safety enhancement is the result of multi-stage work, which is based mainly on the vehicle enhancement and appropriate traffic organization. However, the full separation of vehicle traffic and pedestrians seem to be impossible nowadays. The paper presents a new method for assessing the influence of vehicle structural components on pedestrian kinematics. An integral part of the method is the relationship, named as the k parameter, which can determinate the geometric property of the pedestrian body movement (kinematics) after a collision. The development of the new algorithm is the answer to the problem of assessing the risk posed by the impact of the vehicle with a high bumper/bonnet reference line (e.g. a Sport Utility Vehicle – SUV) on a pedestrian. The presented method can be a useful engineering tool to assess the safety of vehicles, both brand-new and used. The developed test system binds together a new defined kinematic criterion as well as the existing biomechanical criteria (the assessment of vehicles using pedestrian impactors). The presented method was verified on a compact vehicle and a SUV.

Pedestrian Detection and Tracking Using a Dynamic Vision Sensor

Neuromorphic sensors such as the DynamicVision Sensor (DVS) emulate the behavior of the primary vision system. Its asynchronous behavior makes the data processing easier and faster due to the analysis is only in the active pixels. Pedestrian kinematics contains specific movement patterns feasible to be detected, like the angular movement of arms and feet. Some previous methodologies were focused on pedestrian detection based on the static shapes detection like cylinders orcircles, however, they do not take into account the kinematic behavior of the body by itself. In this paper, we presented an algorithm inspired in K-means clustering and describes the analysis of the human kinematics based on DVS in order to detect and track pedestrians in a controlled environment.

Pedestrian simulation: Theoretical models vs. data driven techniques

This paper presents a comparison and relative assessment of data driven techniques and conventional theoretical pedestrian simulation models. Data driven methods are applied for simulating phenomena without a priori knowledge of parameter connections, while indicating high modeling performance. In contrast, theoretical models rely on pedestrian kinematics principles and provide mathematical functions on model parameters. A comparison between locally weighted regression and a social force model in real data (collected by the authors within the framework of this research) suggests superior performance of the data driven model on modeling pedestrian movements. However, a more integrated comparative analysis should be conducted, to validate these preliminary observations. Additional contributions, presented in this research, include an algorithm for eliminating data noise, based on an Unscented Kalman filter and moving average extensions.

A Study on Influence of Minivan Front-End Design and Impact Velocity on Pedestrian Thorax Kinematics and Injury Risk

Thoracic injuries occur frequently in minivan-to-pedestrian impact accidents and can cause substantial fatalities. The present research work investigates the human thoracic responses and injury risks in minivan-to-pedestrian impacts, when changing the minivan front-end design and the impact velocity, by using computational biomechanics model. We employed three typical types of minivan model of different front-end designs that are quite popular in Chinese market and considered four impact velocities (20, 30, 40, and 50 km/h). The contact time of car to thorax region (CTCTR), thorax impact velocity, chest deformation, and thoracic injury risks were extracted for the investigation. The results indicate that the predicted pedestrian kinematics, injury responses, and thoracic injury risks are strongly affected by the variation of the minivan front-end design and impact velocity. The pedestrian thoracic injury risks increase with the increasing vehicle impact velocity. It is also revealed that the application of the extra front bumper is beneficial for reducing the thoracic injury risk, and a relatively flatter minivan front-end design gives rise to a higher thoracic injury risk. This study is expected to be served as theoretical references for pedestrian protection design of minivans.

Analysis of pedestrian kinematics and ground impact in traffic accidents using video records

ABSTRACTPedestrians are exposed to the traffic environment without protection and thereby easily suffer serious traffic injuries when involved in a motor vehicle collision. The aims of this study were to investigate the pedestrian kinematics and ground impact in 200 real-world accident cases with video recordings. The impact velocities, pedestrian kinematics and ground impact were analysed by utilising the video information. The highest frequency of the vehicle impact velocity was estimated to be between 30 and 50 km/h. Sedan impacts led to high rotation angles of pedestrians, and the rotation angles increased as the impact velocities increased. The highest occurring frequency of kinematics involved somersaults which accounted for 39% in sedan accidents. The pedestrian rotation angle and kinematics depends on a vehicle's front shape and impact velocity. Also, the pedestrian rotation angle and kinematics can influence the pedestrian landing mechanisms including the order of the body region landing to the ground and the pedestrians’ landing posture. The findings of the accident analysis will be helpful for future studies on pedestrian protection.

Effects of passenger car front profile and human factors on pedestrian lower extremity injury risk using German in-depth accident data

ABSTRACTThis study aimed to identify the correlations of pedestrian with moderate to untreatable (AIS2+) lower extremity injury risk with the pedestrian kinematics and vehicle front profile variables using real-world accident data. A subsample of 404 pedestrian accident cases with lower extremity injuries was selected from German in-Depth Accident Study (GIDAS) database to conduct statistical analysis. Variance test and logistic regression analysis was performed to analyze associations between selected variables and risk of pedestrian with AIS2+ lower extremtiy injuries. The results revealed that the predicted variables of the impact speed, pedestrian age and weight, the Lower bumper height (LBH) and the Bonnet leading edge height (BLEH) were statistically significant for AIS2+ lower extremity injuries. The higher impact speed, the higher LBH and BLEH corresponded to a greater likelihood of suffering an AIS 2+ lower extremity injury. The results could provide background knowledge for improving pedestrain protective strategies in passenger vehicle design.

Vehicle-pedestrian collisions – Aspects regarding pedestrian kinematics, dynamics and biomechanics

Vehicle-pedestrian collisions result in a substantial number of pedestrian fatalities and injuries worldwide. Concern continues to limit and reduce the tragic consequences suffered by pedestrians involved in road accidents, caused the vehicle-pedestrian accident reconstruction become an important area and distinctly outlined in the reconstruction of road incidents involving vehicle. This paper analyzes the dynamics of vehicle-pedestrian impact influence over pedestrian biomechanics, which is directly connected with the severity of injury after contact with the vehicle profile and with the place where the pedestrian is projected. The main goal of this paper is to highlight some features of reconstruction of road accidents involving pedestrian, looking at the kinematics and dynamics of pedestrian impact for a better understanding of the phenomena that occur. The study on the dynamics and biomechanics of the pedestrian hit by the vehicle is useful in order to understand how the injuries, including the lethal ones, are generated in the collision, what is essential in road accidents reconstruction.