Vehicle-pedestrian Collisions Research Articles

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.

New observations from real-world vehicle-pedestrian collisions in reducing ground related injury by controlling vehicle braking

Pedestrians suffer significant injuries from ground contact, but attempts to reduce them have been limited. A recent study using multi-body simulations showed ground contact injury may be improved by controlling vehicle braking. The aim of the study is to assesses whether controlled braking would be beneficial in real-world collisions. PC-Crash was used to reconstruct 150 freely available real-world vehicle pedestrian video collisions. Pairwise comparison of actual versus controlled braking was then performed for each case. Pedestrian injury evaluation metrics included head injury criterion HIC15 and pelvis contact force, and another metric named separation distance between the vehicle and pedestrian at the instant of ground contact was used to test the feasibility of external airbags for mitigating ground contact. Substantial head and pelvis injury reductions may be possible through the application of controlled braking. Full vehicle braking after first vehicle-pedestrian contact has little influence on overall pedestrian injury outcome. In controlled braking, an external semi-elliptic airbag with a range 2 m can prevent 83.1% ground contact (only 46.6% in actual cases) and there is a high probability (50%) that the available space to control braking is limited if the vehicle deviates from its original lane. Various kinematic explanations are presented, consistent with the principle that the vertical component of the impact on the ground can be reduced by controlling the vehicle braking. Despite the variation in real-world pedestrian collisions, controlled braking may generally provide a benefit for ground contact injuries.

Vision‐based approach for predicting the probability of vehicle–pedestrian collisions at intersections

Road accidents impose serious problems on society. Possible collisions between vehicles and pedestrians must be detected before they occur so that a timely warning may be issued. By using the vision-based approach, this study presents an effective and efficient algorithm to estimate the vehicle-pedestrian collision probability at intersections. The real-time trajectories and movement parameters (position, speed, acceleration or direction) of vehicles and pedestrians are obtained based on state-of-the-art detection and tracking algorithm which include background subtraction method, faster regions with convolutional neural networks and optical flow method. To find the appropriate time to identify the latent collision risk for calculating the collision probability, this study defines the critical time based on different collision patterns of perception-reaction failure and evasive action failure. In addition, based on discrete acceleration and discrete angle, the authors get different extended trajectories which can include most situation when the conflict happened. Trajectories generation probability are given by the discrete choice probability model based on the Logit model to get the accurate collision probability. Real-world video data is implemented to demonstrate the approach. This proposed collision prediction method can provide some important results for designing the intelligent pedestrian signal timing schemes at intersections.

Analysis of craniocerebral injury in facial collision accidents.

Considering that the Pc-Crash multibody dynamics software can reproduce the accident process accurately and obtain the collision parameters of pedestrian heads at the moment of head landing, the finite element analysis method can accurately analyze the injury of the pedestrian head when the boundary conditions are known. This paper combines the accident reconstruction method with the finite element analysis method to study the injury mechanism of pedestrian head impact on the ground in vehicle pedestrian collision accidents to provide a theoretical basis for pedestrian protection and the improvement of vehicle shapes. First, a real-life vehicle pedestrian collision is reproduced by Pc-Crash. The simulation results show that the rigid multibody model can accurately simulate the scene of the accident, then the speed and angle of the pedestrian head landing moment can be obtained at the same time. Second, the finite element model of human heads with a detailed facial structure is established and verified. Finally, the collision parameters obtained from the accident reconstruction are used as the boundary conditions to analyze the collision between the pedestrian head and the ground, and the biomechanical parameters, such as intracranial pressure, von Mises stress, shear stress and strain, can be determined. The results show that the stress wave will propagate inside and outside the skull and cause stress concentration in the skull and the brain tissue to varying degrees after the pedestrian head strikes the ground. When the stress exceeds a certain limit, it will cause different degrees of brain tissue injury.

A profile of traumatic brain injuries and associated cervical spine injuries at a regional hospital in the KwaZulu-Natal Province.

BackgroundClearing the cervical spine in an unconscious blunt trauma patient is an elusive concept. The aim of this study was to describe the incidence of cervical spine injury (CSI) in patients with a traumatic brain injury (TBI). The study was conducted on patients who underwent imaging of both the cervical spine and the brain in one sitting at a busy government healthcare facility in Pietermaritzburg.MethodsThis was a retrospective, cross sectional study of all the trauma patients presenting to a regional hospital emergency department (ED) in the KwaZulu-Natal (KZN) Province, who underwent computed tomography (CT) imaging of the brain and the cervical spine in one sitting during the period January 2016 to June 2016.ResultsAdult males formed the majority (78.9%) of the study population and had the highest incidence of TBI, the most common identified pathology in CT being parenchymal injuries (41%). The mechanisms that resulted in the majority of injuries sustained were assault (38.7%) and motor vehicle collisions (MVCs) (25%), while seven patients (4.76%) had a combined diagnosis of TBI and CSI. The average Glasgow Coma Scale (GCS) was 12.ConclusionYoung adult males are at the greatest risk of sustaining TBI, with assault being the most common mechanism of injury. Combined diagnoses of TBI and CSI are rare and were mostly noted in patients involved in MVCs and pedestrian vehicle collisions. While the chance of an abnormal CT scan increased with a decreasing GCS score, 33% of patients with a mild TBI did not have abnormal CT findings, and 25% patients with severe TBI had no abnormal CT findings.

Vision-Based Personal Safety Messages (PSMs) Generation for Connected Vehicles

Vehicle-to-pedestrian (V2P) communication can significantly improve pedestrian safety in a connected vehicle environment. However, pedestrian safety is hindered as pedestrians often do not carry hand-held devices that provide low latency wireless communication (e.g., dedicated short-range communication (DSRC)-enabled device or emerging 5G-enabled cell phone) to communicate with nearby connected vehicles. The contribution of this paper lies in developing a vision-based approach to generate personal safety messages (PSMs) in real-time utilizing video streams from roadside traffic cameras, following the standard of the Society of Automotive Engineers (SAE) (SAE J2945) that can be used by connected vehicle pedestrian safety applications. Our analysis reveals that the vision-based approach can estimate pedestrians' location and speed more accurately than existing DSRC-enabled pedestrian hand-held devices. A system-level validation was performed by developing a connected vehicle related pedestrian safety application, “pedestrian in signalized crosswalk warning (PSCW),” that uses the generated PSMs from our vision-based approach. The results from the calculated average time-to-collision (TTC) value demonstrate the efficacy of our method in generating real-time collision warnings to avoid possible vehicle-pedestrian collisions. Our analysis also shows that the vision-based pedestrian safety warning system satisfies the latency requirement for the PSCW safety application in a connected vehicle environment.

Pedestrian-Vehicle Collision Vulnerability in Senior Citizens’ Walking Environment: An Area-Level Investigation of Seoul, South Korea

The safety of senior pedestrians is a major challenge in cities, particularly in a rapidly aging society. This study takes place in Seoul, South Korea, where pedestrian safety in highly urban environments poses a major threat. Using several big databases, the study investigated 142 frequent collision areas where 583 pedestrian-vehicle collisions involving seniors were reported in 2017. Using Poisson and negative binomial regression, we modeled the relationship between collisions and three sets of area-specific environmental characteristics: land-use; transportation and pedestrian infrastructures; and population characteristics. Two different scales of walking environment of senior citizens were investigated: the frequent collision areas (200-meter radius), and their pedestrian sheds (1-kilometer radius). The study further dissectedcommercial areas and roadways into types of destinations and roadway classifications, and found that the neighborhoods with a higher number of medical institutes and a denser network of minor roads were associated with higher risk of collisions. The study found that senior pedestrians were more vulnerable in low-income neighborhoods, especially in the areas with larger resident and floating population of seniors. The findings from the study provided some meaningful information on the risk of collision, and policy implications to improve the safety of senior pedestrians.

Representing two road traffic collisions in one Accimap: highlighting the importance of emergency response and enforcement in a low-income country

Seemingly erratic pedestrian crossing has become a major source of vehicle-pedestrian collisions on highways in Bangladesh, and across other low- and middle-income countries (LMICs). In this article, we approach the challenge from a sociotechnical systems perspective by using the Accimap method to analyse a pair of time-separated yet interconnected road traffic collisions. The first event involved a truck colliding with a road divider; in the second, fatal incident, a bus hit a university student. The traditional-style investigation conducted immediately after the collision apportioned blame to end users, that is, drivers and pedestrian; however, application of sociotechnical systems thinking revealed the contribution from lack of emergency response and enforcement among many other important factors. Results and recommendations are discussed in terms of reducing the chance and severity of such collisions across LMICs, and in terms of the need to look beyond the end-user, a focus that remains dominant in such settings. Practitioner summary: This paper applies sociotechnical systems thinking to pedestrian safety in Bangladesh by analysing two inter-connected road traffic collisions using a single Accimap. The findings emphasise the importance of implementing road safety interventions that target all system levels, and draw attention to the importance of post-collision response in low-income settings. Abbreviation: BUET: Bangladesh University of Engineering and Technology

Comparison of exposure in pedestrian crash analyses: A study based on zonal origin-destination survey data

In recent years, the importance of exposure for pedestrian crash analysis has received increasing attention. Unlike the case of motor vehicle crashes, the definition of exposure for pedestrian crash analysis is sometimes vague and the mechanism behind the association between exposure and pedestrian crash is often ambiguously defined. In this study, the number of roads crossed and walking distance is estimated using an integrated trip assignment method at the aggregate level. The number of walking trips are also considered and compared with the distance travelled and road crossing based exposure using joint probability models. Results show that models using the road crossing based exposure approach provides the best model fit. It is found that the number of roads crossed is the most sensitive to vehicle-pedestrian collisions, as it is more strongly correlated to potential vehicle-pedestrian interactions. The results also indicate that the sensitivity of number of road crossed could vary with road types, and road safety measures for pedestrian protection should be widely implemented on low-grade roads.

Uncertain inverse method by the sequential FOSM and its application on uncertainty reconstruction of vehicle–pedestrian collision accident

Uncertainties widely exist in practical engineering problems. In order to effectively evaluate the unknown parameters under the uncertain measured responses, an efficient uncertain inverse method based on the sequential first order and second moment (FOSM) is proposed. The uncertain inverse problem is firstly transformed as a two-layer optimization problem involved uncertainty propagation and optimization inverse. In the inner layer, the maximum entropy principle is employed to model the probability density functions (PDFs) of the unknown parameters, and the sequential FOSM method is used to estimate the cumulative distribution functions of the calculated responses. In the outer layer, the intergeneration projection genetic algorithm is adapted to achieve the efficient solving of the transformed optimization problem. Two numerical examples are provided to verify the effectiveness of the proposed uncertain inverse method. Further, the proposed uncertain inverse method is applied to the reconstruction of the vehicle–pedestrian collision accident, and the statistical moments and PDFs of the vehicle state parameters before collision are reasonably identified.

Pedestrian gaits observed from actual pedestrian-vehicle collisions

The problem of injury protection for pedestrian is a research hot spot in traffic safety, and simulations are important research tools. In the process of design of simulation experiments, pedestrian gaits become more and more important. Hence in the research three pedestrian gait serials (walking, running and emergency) were found through observing and reconstructing 150 vehicle-pedestrian collision videos. Further studies had found that pedestrian speed and pedestrian injury are different among the three gait serials and there is significant difference between the Pedestrian Speed Before the Collision (PSBC) and the Pedestrian Speed at the Instant of the Collision (PSIC) in the same gait serial; for the emergency gait serial, there is significant difference between the estimated and reconstructed pedestrian heights; and there is high relevance between angles of the left extremities and the corresponding right extremities. Furthermore, based on results observed from the 150 videos and those existing research results, ten pedestrian gaits in each gait serial were proposed, simulation results shown that the pedestrian injury in different gait serial and in different gaits in the same gait serial are all different. The observed pedestrian gaits will help us to design a more objective simulation experiments in the future in analyzing pedestrian injury.

Effects Influencing Pedestrian–Vehicle Crash Frequency by Severity Level: A Case Study of Seoul Metropolitan City, South Korea

This study aimed to determine how built environments affect pedestrian–vehicle collisions. The study examined pedestrian–vehicular crashes that occurred between 2013 and 2015 in Seoul, Korea, by comparing and analyzing different effects of the built environment on pedestrian–vehicle crashes. Specifically, the study analyzed built environment attributes, land use environment, housing types, road environment, and traffic characteristics to determine how these factors affect the severity of pedestrian injury. The results of the statistical analysis appear to infer that the built environment attributes had dissimilar impacts on pedestrian collisions, depending on the injury severity. In general, both incapacitating and non-incapacitating injuries appear to be more likely to be caused by the built environment than fatal and possible injuries. These results highlight the need to consider injury severity when implementing more effective interventions and strategies for ensuring pedestrian safety. However, because of the small sample size, an expanded research project regarding this issue should be considered, as it would contribute to the development and implementation of effective policies and interventions for pedestrian safety in Korea. This study therefore offers practical information regarding the development of such an expanded study to inform future traffic safety policies in Seoul to establish a “safe walking city.”

Pedestrian Throw Distance Prediction from Vehicle Damage Intensity

One of the main points to be addressed when analysing vehicle-pedestrian collisions is the vehicle impact speed. If the traffic accident is not recorded on camera, and there are no skid marks nor tachograph in the vehicle, the parameter is determined on the basis of empirical models. All empirical models for ascertaining vehicle speed are based on the pedestrian throw distance, which is not always known because of an unidentified vehicle-pedestrian collision point or the final rest position of the pedestrian after collision. This paper shows a description of a vehicle damage recorded in an ordinal scale and determines the pedestrian throw distance prediction model from the vehicle damage established in such a way. If the accident scene is documented by photographs, the damage can be classified, and by applying a validated model, the pedestrian throw distance envisaged. Then, by applying an empirical model, one can determine the speed of the vehicle at the time of collision with a pedestrian. Two databases were formed during the research. The first is based on real-life traffic accidents (expert witnessing of the professors from the Faculty of Technical Sciences). The second is based on traffic accident simulations as part of PC Crash software package.

Daily and Latent Lagged Effects of Rainfall on Pedestrian–Vehicle Collisions

AbstractWalking safety has been a primary concern for researchers and authorities, who have developed numerous studies concerning the interaction between pedestrians and vehicles. Nevertheless, few studies have focused on the impacts of weather conditions on pedestrian–vehicle collisions. This research aims at improving knowledge on this subject by investigating the impact of daily precipitation and the lagged effects associated with past accumulated precipitation. Using the city of Porto, Portugal, as a case study, an incremental approach consisting of three models, one Poisson and two negative binomial, was developed to explore the relation between weather conditions and the occurrence of pedestrian–vehicle collisions. The first model accounts exclusively for meteorological variables, providing an insight into the trends of crash frequency under the effects of temperature and precipitation. Then, variables for road classification and land use were introduced in the second and third models, respectively, to account for the diversity of the urban environment. These variables act as proxies for the level of exposure associated with different types of urban space, allowing for a more in-depth understanding of the impacts caused by meteorological conditions. The modeling results show that the number of pedestrian–vehicle collisions tends to increase on rainy days, following the general trend observed in the literature for other types of crashes. Regarding the lagged effects, the results show that the number of pedestrian–vehicle collisions is likely to decrease after a wet week but increases after a wet month.

Biomechanical impact testing of synthetic versus human cadaveric tibias for predicting injury risk during pedestrian-vehicle collisions

Objective: The tibia is the most commonly fractured long bone in a pedestrian-vehicle collision. The standard injury assessment tool is the “legform,” a device that mimics the human lower limb under impact loads. These devices are designed to identify the impact load that will cause the onset of injury, rather than replicate the type and severity of fracture. Thus, this study is the first to determine if composite tibias made by Sawbones (Pacific Research Labs, Vashon, WA, USA) designed for orthopedic biomechanics research, could also potentially be used for traffic safety research by simulating both the damage tolerance of human cadaveric tibias for peak force and bending moment and the fracture patterns themselves, thereby more accurately predicting injury type during real-world pedestrian-vehicle collisions.Methods: Synthetic tibias (n = 6) and human cadaveric tibias (n = 6) were impacted at midshaft at 8.3 m/s (i.e., 30 km/h) under 3-point bending using a pneumatic impacting apparatus. Fracture force, bending moment, and fracture patterns were compared between the two groups, and Weibull survivability curves generated for force and moment results, to identify injury risk thresholds.Results: There was no difference for synthetic vs. cadaveric tibias regarding impact force (4271+/-938 N vs. 4889+/-993 N, p = 0.44) or bending moment at fracture (275+/-64 Nm vs. 302+/-107 Nm, p = 0.69). Force-time curves for all tibias were similar in shape based on the first three Principal Components (p > 0.14). Weibull survivability curves had differences in shape and in the 10% risk of fracture limits, with force thresholds of 2873 N for the synthetic vs. 3386 N for the cadaveric, and bending moment limits of 180 Nm for the synthetic compared to 157 Nm for the cadaveric. All fracture patterns were clinically realistic, but not consistent between groups. The coefficient of variation for synthetic tibias was >0.2 for both peak force and bending moment, which precludes their use as a reproducible test surrogate for injury prediction.Conclusions: Synthetic composite tibias offer the potential for developing a frangible test surrogate, and matched cadaveric response in several respects. However, the repeatability was not high enough for them to be used in their present form for injury prediction.

Vehicle Trajectory Prediction and Collision Warning via Fusion of Multisensors and Wireless Vehicular Communications.

Driver inattention is one of the leading causes of traffic crashes worldwide. Providing the driver with an early warning prior to a potential collision can significantly reduce the fatalities and level of injuries associated with vehicle collisions. In order to monitor the vehicle surroundings and predict collisions, on-board sensors such as radar, lidar, and cameras are often used. However, the driving environment perception based on these sensors can be adversely affected by a number of factors such as weather and solar irradiance. In addition, potential dangers cannot be detected if the target is located outside the limited field-of-view of the sensors, or if the line of sight to the target is occluded. In this paper, we propose an approach for designing a vehicle collision warning system based on fusion of multisensors and wireless vehicular communications. A high-level fusion of radar, lidar, camera, and wireless vehicular communication data was performed to predict the trajectories of remote targets and generate an appropriate warning to the driver prior to a possible collision. We implemented and evaluated the proposed vehicle collision system in virtual driving environments, which consisted of a vehicle–vehicle collision scenario and a vehicle–pedestrian collision scenario.

Injury Analysis of Vehicle-Pedestrian Collision Based on Orthogonal Experiments

This paper studies the influence of different factors on pedestrian head injury in vehicle-pedestrian collisions. PC-Crash software is used to construct simulation experiments under ten factors. The research shows that the injury to pedestrians in reverse impact is greater than that to pedestrians in forward impact. With the acceleration of vehicle speed, the HIC value of pedestrians will increase with the increase of the height of the front hood from the ground. When the vehicle speed is less than 40 km/h, the injury to pedestrians in a forward-leaning emergency posture is smaller, and the injury to a standing emergency posture is the highest.

A Retrospective Analysis of the Cases Involving Road-Traffic Accidents in a Pediatric Intensive Care Unit

Introduction: In this study, we aimed to emphasize the importance of preventive measures by examining the clinical features of the cases involving road-traffic accidents in the pediatric intensive care unit (PICU). Materials and Methods: A total of 46 traffic-accident cases involving patients who were younger than 18 years and were admitted to PICU were examined retrospectively. The cases were evaluated for age, gender, the time and location of hospital admission, the type of accident, the sites of injury, the duration of intensive care, the requirement for inotropics, antiepileptics, antibiotics, transfusion, and ventilator, and mortality rates. Results: The average age of patients was 8.54±5.17 years; 67.4% of them were male (n=31). The out-of-vehicle traffic accidents were the most common type of accidents (71.7%) while the in-vehicle accidents were the least common type (13%). The PICU admissions due to traffic accidents were more frequent in summer (34.8%) and autumn (32.6%). Of the patients, 28 (61.9%) had trauma in a single region, and 18 (39.1%) had traumas in multiple regions. Among those with single-site trauma, the most frequent trauma site was head and neck (32.6%). The most frequent complications during the PICU stay were cerebral edema (24.7%) and intracranial hemorrhage (16.9%). Seven patients have died (15.2%) due to the reasons, most of which (n=6, 85.7%) were out-of-vehicle accidents involving vehicle-pedestrian collisions. Conclusion: The study indicated that males were more frequently involved in road traffic accidents and that pedestrians had higher rates of serious injury and mortality. More effective training programs, security measures, legislation, and structural improvements are required regarding traffic accidents.

Parameter sensitivity analysis of pedestrian head dynamic response and injuries based on coupling simulations.

There are a very limited number of reports studying on the dynamic response and injuries of pedestrian head in the scenarios with head hitting windshield. This study aims to investigate the significant factors that affect the dynamic response and injuries of pedestrian head through finite element-multi-body coupling simulations. Two finite element vehicle models and two multi-body pedestrian human models were used to build the coupling simulations. Orthogonal experimental design and analysis of variance were used for parameter combination and data analysis. This study demonstrated that the dynamic response of pedestrian head and HIC15 were strongly associated with collision speed and pedestrian orientation. Vehicle type had a significant influence on the dynamic response of pedestrian head and HIC15, while there was no significant relationship between the dynamic response of pedestrian head and HIC15 and the size of pedestrian human models. Collision speed, pedestrian orientation, and vehicle type should be prioritized over the other collision parameters in the study of head injury mechanism and reconstruction of vehicle-pedestrian collisions in the scenarios with head hitting windshield.

Modified Driving Safety Field Based on Trajectory Prediction Model for Pedestrian–Vehicle Collision

Pedestrian–vehicle collision is an important component of traffic accidents. Over the past decades, it has become the focus of academic and industrial research and presents an important challenge. This study proposes a modified Driving Safety Field (DSF) model for pedestrian–vehicle risk assessment at an unsignalized road section, in which predicted positions are considered. A Dynamic Bayesian Network (DBN) model is employed for pedestrian intention inference, and a particle filtering model is conducted to simulate pedestrian motion. Driving data collection was conducted and pedestrian–vehicle scenarios were extracted. The effectiveness of the proposed model was evaluated by Monte Carlo simulations running 1000 times. Results show that the proposed risk assessment approach reduces braking times by 18.73%. Besides this, the average value of TTC−1 (the reciprocal of time-to-collision) and the maximum TTC−1 were decreased by 28.83% and 33.91%, respectively.