Trajectory planning framework for autonomous vehicles based on collision injury prediction for vulnerable road users.

Due to the escalating occurrence and high casualty rates of accidents involving Electric Two-Wheelers (E2Ws), it has become a major safety concern on the roads. Additionally, with the widespread adoption of current autonomous driving technology, a greater challenge has arisen for the safety of vulnerable road participants. Most existing trajectory planning methods primarily focus on the safety, comfort, and dynamics of autonomous vehicles themselves, often overlooking the protection of vulnerable road users (VRUs), typically E2W riders. This paper aims to investigate the kinematic response of E2Ws in vehicle collisions, including the 15 ms Head Injury Criterion (HIC15). It analyzes the impact of key collision parameters on head injuries, establishes injury prediction models for anticipated scenarios, and proposes a trajectory planning framework for autonomous vehicles based on predicting head injuries of VRUs. Firstly, a multi-rigid-body model of two-wheeler-vehicle collision was established based on a real accident database, incorporating four critical collision parameters (initial collision velocity, initial collision position, and collision angle). The accuracy of the multi-rigid-body model was validated through verifications with real fatal accidents to parameterize the collision scenario. Secondly, a large-scale effective crash dataset has been established by the multi-parameterized crash simulation automation framework combined with Monte Carlo sampling algorithm. The training and testing of the injury prediction model were implemented based on the MLP + XGBoost regression algorithm on this dataset to explore the potential relationship between the head injuries of the E2W riders and the crash variables. Finally, based on the proposed injury prediction model, this paper generated a trajectory planning framework for autonomous vehicles based on head collision injury prediction for VRUs, aiming to achieve a fair distribution of collision risks among road users. The accident reconstruction results show that the maximum error in the final relative positions of the E2W, the car, and the E2W rider compared to the real accident scene is 11 %, demonstrating the reliability of the reconstructed model. The injury prediction results indicate that the MLP + XGBoost regression prediction model used in this article achieved an R2 of 0.92 on the test set. Additionally, the effectiveness and feasibility of the proposed trajectory planning algorithm were validated in a manually designed autonomous driving traffic flow scenario.

Understanding nonuse of mandatory e-scooter helmets.

OBJECTIVES: Head injuries resulting from e-scooter use have led to calls for helmet use to be promoted or mandatory. Helmet use is mandatory for e-scooters in Australia but observational studies have reported significant levels of nonuse, particularly by riders of shared e-scooters. The aim of this study is to understand whether nonuse in the mandatory context is a consistent behavior for an individual or is situationally-influenced, and what are the factors associated with nonuse. METHODS: An online survey was completed between 2022 and 2023 by 360 adult e-scooter riders in Canberra, Australia. Riders were asked whether they had worn a helmet on their last ride and how often they had not worn a helmet when riding in the last 30 days. The survey also asked about rider characteristics (demographics, frequency of e-scooter and bicycle use, perceived risk of e-scooter use, e-scooter ownership, and risky behaviors while riding), trip duration and perceptions of the helmet requirement (knowledge of and support for the law). RESULTS: Respondents were mostly male, young, highly educated, and full-time workers. Of the 29.1% of riders who reported riding without a helmet in the last 30 days, 24.4% had worn a helmet at least once during that period and 4.8% had consistently not worn a helmet. Younger age, shared e-scooter use and more frequent riding frequency (shared e-scooters only) were associated with helmet nonuse in the bivariate analyses but not in the logistic regression. Logistic regression showed that the independent predictors of helmet nonuse were the number of risky riding behaviors, lack of knowledge, and lack of support for the law. CONCLUSIONS: Most nonuse of helmets in a mandatory context seems to be situational, rather than consistent. Many of the factors associated with nonuse of helmets for e-scooters are similar to those reported for bicycles. Nonuse of helmets appears to be one of a number of risky behaviors performed by riders, rather than being primarily an outcome that is specific to factors associated with helmets (e.g., concerns about hygiene, discomfort or availability).

Investigation of fatal traumatic head injuries.

BACKGROUND: Traumatic head injuries (THIs) are one of the major causes of death in forensic cases. The aim of this study was to investigate the characteristics of patients with fatal THIs. METHODS: In this study, a total of 311 patients with fatal THIs, who underwent postmortem examinations and/or autopsies, were retrospectively analyzed. Cases were evaluated based on sex, age group, incident origin, cause of the incident, presence of skull fracture, type of fractured bone (if any), fracture localization and pattern, presence and type of intracranial lesion (if any), and cause of death. RESULTS: Out of the patients, 242 (77.8%) were male and 69 (22.2%) were female. Accidents accounted for 235 (75.6%) of the incidents, with in-vehicle traffic accidents causing 117 (37.6%). In 221 cases (71.1%), intracranial lesions and skull fractures were observed together. The most common fractures were base fractures (171 cases) and temporal bone fractures (153 cases). The rate of intracranial hemorrhage was lower in the adult age group (69.7%) compared to the older age group (92.6%). CONCLUSION: The results obtained in this study indicate that the cause of the incident, type of fracture, presence of skull base fracture, and multiple skull fractures increase the likelihood of fatalities. The occurrence of skull fractures reduces intracranial pressure, thereby decreasing the incidence of intracranial lesions. The development and effective enforcement of road traffic safety policies and regulations will reduce the incidence of fatalities.

Bicycle-related accidents in Rome: Investigating clinical patterns, demographics, injury contexts, and health outcomes for enhanced public safety.

INTRODUCTION: This study aims to analyze the clinical characteristics, demographic features, and injury circumstances of patients admitted to the Emergency Department (ED) at Fondazione Policlinico Universitario A. Gemelli (IRCCS) in Rome, Italy, due to bicycle accidents. METHODS: Data on clinical characteristics, accident timing, injury circumstances, and helmet use were collected for ED patients involved in bicycle accidents from January 2019 to December 2022. Subsequently, Abbreviated Injury Scale codes of all diagnoses were recorded and the Injury Severity Score was calculated. RESULTS: Over the study period, 763 patients were admitted to the ED following bicycle accidents, with a 0.3 % fatality rate and a 30.4 % frequency of multitrauma. Multivariate analysis revealed that collisions with other vehicles increased trauma severity and the risk of ICU admission. Conversely, helmet use was associated with reduced severity of head trauma and a lower likelihood of ICU admission. Notably, toxicological investigations were not conducted for any ED-admitted patients. CONCLUSIONS: Although a low mortality rate and a low incidence of multi-trauma have been shown in comparison to other nations, it is necessary to adopt prevention strategies like safety devices, more cycle paths, and better infrastructures on the one hand, and stricter laws on the other. It is essential to require toxicological testing in Italy for all accidents involving this means of transport, and to make helmet use compulsory for all ages.

Injury Patterns of Electric-Scooter Related Trauma: A Systematic Review With Proportion Meta-Analysis.

Electric scooter (ES)-related injuries are increasing but poorly described. Clinicians need more information to be prepared for these patients. We supposed two prevalent patterns of patients: mildly injured (predominant upper-limb injuries) and severely injured (predominant head trauma). This study aims to understand the frequency of ES-related injuries and patients' characteristics despite the heterogeneity of data currently available. A systematic review with a proportion meta-analysis was conducted on studies with a multidisciplinary description of ES-related injuries in adult patients (PROSPERO-ID: CRD42022341241). Articles from inception to April 2023 were identified in MEDLINE, Embase, and Cochrane's databases. The risk of bias was evaluated using ROBINS-I. Twenty-five observational studies with 5387 patients were included in the meta-analysis, depending on reported data. Upper-limb (31.8%) and head (19.5%) injuries are the most frequent (25/25 studies included). When injured while riding, 19.5% of patients are intoxicated with drugs/alcohol, and only 3.9% use a helmet, increasing the possibility of severe injuries. About 80% of patients are victims of spontaneous falls. Half of the patients self-present to the ED, and 69.4% of cases are discharged directly from the ED. Studies' limitations include an overall moderate risk of bias and high heterogeneity. Electric scooter-related accidents are commonly associated with upper-limb injuries but often involve the head. Spontaneous falls are the most common mechanism of injury, probably related to frequent substance abuse and helmet misuse. This hot topic is not adequately investigated due to a lack of data. A prospective registry could fill this gap.

Abusive head trauma: The body of the iceberg - A population-based survey on prevalence and perpetrators.

BACKGROUND: Research on abusive head trauma (AHT) is usually research on clinically identified cases, while population-based studies, having the potential to identify cases of shaking that did not end with hospital admission, are missing to date. OBJECTIVE: Thus, we aimed to assess the prevalence of AHT and associated risk factors in a representative sample of the German population. PARTICIPANTS AND SETTING: We conducted a cross-sectional, observational study in Germany from July to October 2021. Using different sampling steps including a random route procedure, a probability sample of the German population was generated. The final sample consisted of 2503 persons (50.2 % female, mean age: 49.5 years). METHODS: Participants were asked about sociodemographic information in a face-to-face interview and whether they had been ever responsible for the care of an infant and whether they had ever performed potential harmful methods including shaking to calm it, intimate partner violence (IPV) and adverse childhood experiences (ACEs) using a questionnaire. RESULTS: In total, 1.4 % of women (N = 18) and 1.1 % of men (N = 13) reported to have at least once shaken an infant to calm it. Ever having used a potential harmful parenting method in calming an infant was reported by 4.9 % of women (N = 61) and 3.1 % (N = 39) of men. No gender differences were seen. A low income, living with someone under 16 in the household and victimization and perpetration of IPV and ACEs are associated with increased risks of shaking and other potential harmful methods to calm an infant. CONCLUSIONS: Our data suggest that despite better knowledge on the dangers of shaking, the percentage of women that shake infants might be higher than previously thought. Also, intimate partner violence and ACEs are key risk factor for shaking and harmful parenting behaviors in general. This has important implications for future prevention programs.

A lucid interval in a victim of abusive head trauma with multiple parenchymal lacerations.

Abusive head trauma (AHT) is a leading cause of abusive deaths in children under age one. AHT can include intracranial hemorrhages, hypoxic ischemic injury, or parenchymal lacerations. Most infants with parenchymal lacerations present with acute neurological symptoms. There has been some published literature on lucid intervals in cases of AHT; however, there has not been a described lucid interval with parenchymal lacerations. Parenchymal lacerations typically present with acute symptomatology such as seizures, alteration in mental status, or increased fussiness/lethargy given the damage to neurons and brain structure. We present a case of a healthy 2-month-old who ultimately was diagnosed with AHT and three parenchymal lacerations and had a 2.5 hour period of normal neurological status prior to acute decompensation.

A 10-Year Retrospective Review of Playground-Associated Craniofacial Injuries in the Pediatric Patient Population.

This retrospective study utilized the National Electronic Injury Surveillance System (NEISS) database to identify pediatric emergency department (ED) patients with playground-associated craniofacial injuries between January 2012 and December 2021. A total of 25 414 patients were identified. The majority of injuries occurred in preschool and elementary school-age children (90.3%) and patients were more commonly boys (59.3%). Injuries most often involved the head/scalp (52.4%), face (30.4%), and mouth (11.9%). Infant (32.7%) and teen (40.0%) injuries most commonly involved swings, whereas preschool (23.1%) and elementary school (28.1%) injuries were mostly associated with slides and climbers, respectively. Most patients were treated in the ED and discharged to home (96.5%), a small portion required hospitalization (1.6%), and one death was reported. Although the majority of the injuries were relatively minor and resulted in same-day discharges, these injuries can result in serious physical harm, emotional stress, and unexpected financial burdens. Proper education and supervision regarding safe play is important to prevent these injuries.

Retinal hemorrhage variation in inertial versus contact head injuries.

BACKGROUND: Abusive head trauma (AHT) is frequently accompanied by dense/extensive retinal hemorrhages to the periphery with or without retinoschisis (complex retinal hemorrhages, cRH). cRH are uncommon without AHT or major trauma. OBJECTIVE: The study objectives were to determine whether cRH are associated with inertial vs. contact mechanisms and are primary vs. secondary injuries. PARTICIPANTS AND SETTING: This retrospective study utilized a de-identified PediBIRN database of 701 children <3-years-old presenting to intensive care for head trauma. Children with motor vehicle related trauma and preexisting brain abnormalities were excluded. All had imaging showing head injury and a dedicated ophthalmology examination. METHODS: Contact injuries included craniofacial soft tissue injuries, skull fractures and epidural hematoma. Inertial injuries included acute impairment or loss of consciousness and/or bilateral and/or interhemispheric subdural hemorrhage. Abuse was defined in two ways, by 1) predetermined criteria and 2) caretaking physicians/multidisciplinary team's diagnostic consensus. RESULTS: PediBIRN subjects with cRH frequently experienced inertial injury (99.4 % (308/310, OR = 53.74 (16.91-170.77)) but infrequently isolated contact trauma (0.6 % (2/310), OR = 0.02 (0.0004-0.06)). Inertial injuries predominated over contact trauma among children with cRH sorted AHT by predetermined criteria (99.1 % (237/239), OR = 20.20 (6.09-67.01) vs 0.5 % (2/339), OR = 0.04 (0.01-0.17)). Fifty-nine percent of patients with cRH, <24 h altered consciousness, and inertial injuries lacked imaging evidence of brain hypoxia, ischemia, or swelling. CONCLUSIONS: cRH are significantly associated with inertial angular acceleration forces. They can occur without brain hypoxia, ischemia or swelling suggesting they are not secondary injuries.

Head trauma analysis of laboratory reconstructed headers using 1966 Slazenger Challenge and 2018 Telstar 18 soccer balls.

Retired soccer players are presenting with early onset neurodegenerative diseases, potentially from heading the ball. It has been proposed that the older composition of soccer balls places higher strains on brain tissues. The purpose of this research was to compare the dynamic head response and brain tissue strain of laboratory reconstructed headers using replicas of the 1966 Slazenger Challenge and 2018 Telstar 18 World Cup soccer balls. Head-to-ball impacts were physically conducted in the laboratory by impacting a Hybrid III head form at three locations and four velocities using dry and wet soccer ball conditions, and computational simulation was used to measure the resulting brain tissue strain. This research showed that few significant differences were found in head dynamic response and maximum principal strain between the dry 1966 and 2018 balls during reconstructed soccer headers. Headers using the wet 1966 soccer ball resulted in higher head form responses at low-velocity headers and lower head responses as velocities increased. This study demonstrates that under dry conditions, soccer ball construction does not have a significant effect on head and brain response during headers reconstructed in the laboratory. Although ball construction didn't show a notable effect, this study revealed that heading the ball, comparable to goalkeeper kicks and punts at 22 m/s, led to maximum principal strains exceeding the 50% likelihood of injury risk threshold. This has implications for the potential risks associated with repetitive heading in soccer for current athletes.

Predictors of neurologic outcomes and mortality in physically abused and unintentionally injured children: a retrospective observation study.

OBJECTIVES: This study aimed to identify the predictors of neurologic outcomes and mortality in physically abused and unintentionally injured children admitted to intensive care units (ICUs). METHODS: All maltreated children were admitted to pediatric, neurosurgical, and trauma ICUs between 2001 and 2019. Clinical factors, including age, sex, season of admission, identifying settings, injury severity score, etiologies, length of stay in the ICU, neurologic outcomes, and mortality, were analyzed and compared between the physically abused and unintentionally injured groups. Neurologic assessments were conducted using the Pediatric Cerebral Performance Category scale. The study was approved by the Institutional Review Board of Chang Gung Memorial Hospital and the Ethics Committee waived the requirement for informed consent because of the anonymized nature of the data. RESULTS: A total of 2481 children were investigated; of them, there were 480 (19.3%) victims admitted to the ICUs, including 156 physically abused and 324 unintentionally injured. Age, history of prematurity, clinical outcomes, head injury, neurosurgical interventions, clinical manifestations, brain computed tomography findings, and laboratory findings significantly differed between them (all p < 0.05). Traumatic brain injury was the major etiology for admission to the ICU. The incidence of abusive head trauma was 87.1% among the physically abused group. Only 46 (29.4%) and 268 (82.7%) cases achieved favorable neurologic outcomes in the physically abused and unintentionally injured groups, respectively. Shock within 24 h, spontaneous hypothermia (body temperature, < 35 °C), and post-traumatic seizure were strongly associated with poor neurologic outcomes and mortality in both groups. CONCLUSIONS: Initial presentation with shock, spontaneous hypothermia at ICU admission, and post-traumatic seizure were associated with poor neurologic outcomes and mortality in physically abused and unintentionally injured children.

Abusive head trauma in infants: An observational single centre study comparing developmental and functional outcome between 18 months and 5 years.

BACKGROUND: Abusive head trauma (AHT) is a major cause of traumatic brain injury in infancy. This exploratory study compared standardized developmental assessment versus functional outcome assessment between 18 months and 5 years of age following AHT in infancy. METHODS: Observational cross-sectional study after surviving AHT in infancy. Seventeen children between 18 months and 5 years of age underwent clinical examination, developmental assessment using the Schedule of Growing Skills II (SGS II) and functional assessment using the Glasgow Outcome Scale-Extended Pediatric Revision (GOS-E Peds). Additional clinical information was extracted from medical records. RESULTS: Age at assessment ranged from 19 to 53 months (median 26 months). Most (n = 14) were delayed in at least 1 domain, even without neurological or visual impairment or visible cortical injury on neuroimaging, including 8 children with favourable GOS-E Peds scores. The most affected domain was hearing and language. Delay in the manipulative domain (n = 6) was associated with visual and/or neurological impairment and greater severity of delay across multiple domains. Eleven (64.7 %) had GOS-E Peds scores indicating good recovery, with positive correlation between GOS-Peds scores and number of domains delayed (r = 0.805, p < 0.05). CONCLUSION: The SGS-II detects behavioural and cognitive deficits not picked up by the GOS-E Peds. Combining both tools for assessment of AHT survivors under 5 years of age provides a comprehensive profile which addresses multiple domains of development and function, facilitating targeted intervention. Detection of developmental problems in the majority of survivors makes AHT prevention a public health priority.

The Structural Response of the Human Head to a Vertex Impact.

In experimental models of cervical spine trauma caused by near-vertex head-first impact, a surrogate headform may be substituted for the cadaveric head. To inform headform design and to verify that such substitution is valid, the force-deformation response of the human head with boundary conditions relevant to cervical spine head-first impact models is required. There are currently no biomechanics data that characterize the force-deformation response of the isolated head supported at the occiput and compressed at the vertex by a flat impactor. The effect of impact velocity (1, 2 or 3 m/s) on the response of human heads (N = 22) subjected to vertex impacts, while supported by a rigid occipital mount, was investigated. 1 and 2 m/s impacts elicited force-deformation responses with two linear regions, while 3 m/s impacts resulted in a single linear region and skull base ring fractures. Peak force and stiffness increased from 1 to 2 and 3 m/s. Deformation at peak force and absorbed energy increased from 1 to 2 m/s, but decreased from 2 to 3 m/s. The data reported herein enhances the limited knowledge on the human head's response to a vertex impact, which may allow for validation of surrogate head models in this loading scenario.

Adolescent alcohol and cannabis use as risk factors for head trauma in the Northern Finland Birth Cohort study 1986.

BACKGROUND: The aim of this study was to assess the associations between cannabis use and frequency of alcohol intoxication in adolescence with the risk of traumatic brain injury and craniofacial fractures in early adulthood. Hypothesis was that using alcohol and cannabis in adolescence could increase the risk for head traumas. METHODS: Data from the Northern Finland Birth Cohort 1986 (n = 9432 individuals) were used to investigate the prospective association between the self-reported frequency of alcohol intoxication (n = 6472) and cannabis use (n = 6586) in mid-adolescence and register-based, head trauma diagnoses by ages 32-33 years. To test the robustness of these associations, the statistical models were adjusted for a range of other confounders such as illicit drug use, previous head trauma and self-reported mental health problems. RESULTS: In multivariate analyses, cannabis use was statistically significantly associated with a greater risk of traumatic brain injury among females [hazard ratio (HR) 1.9, 95% confidence interval (CI) 1.1-3.2, P = 0.024). Frequent alcohol intoxication was a statistically significant independent risk factor for both traumatic brain injury (HR 2.6, 95% CI 1.7-3.9, P < 0.001) and craniofacial fractures (HR 2.7, 95% CI 1.6-4.8, P < 0.001) among males. CONCLUSIONS: Cannabis use in adolescence appears to associate independently with elevated risk for traumatic brain injury among females, and frequent alcohol intoxication in adolescence seems to associate with elevated risk of both traumatic brain injury and craniofacial fractures among males.

Assessment of child safety on bicycles in baby carriers - The importance of evaluating both head and neck injuries.

INTRODUCTION: The paper addresses an important accident type that involves children in bicycle seats - the bicycle fall over. It is a significant and common accident type and many parents have been reported to experience this type of "close call." The fall over occurs at low velocities and even while a bicycle is standing still, and may result from a split-second lack of attention on behalf of the accompanying adult (e.g. while loading groceries, i.e. while not being exposed to traffic per se). Moreover, irrespective of the low velocities involved, the trauma that may result to the head of the child is considerable and may be life-threatening, as shown in the study. METHOD: The paper presents two methods to address this accident scenario in a quantitative way: in-situ accelerometer-based measurement and numerical modeling approaches. It is shown that the methods produce consistent results under the prerequisites of the study. They are therefore promising methods to be used in the study of this type of accident. RESULTS: The importanance of the protective role of a child helmet is without discussion in everyday traffic.However, this study draws attention to one particular effect observed in this accident type: that the geometry of the helmet may at times expose the child's head to considerably larger forces, by having contact with the ground. The study also highlights the importance of neck bending injuries during bicycle fall over, which are often neglected in the safety assessment - not only for children in bicycle seats. The study concludes that considering only head acceleration may lead to biased conclusions about using helmets as protective devices.

ICD-10 codes for surveillance of non-fatal abusive head trauma in Aotearoa New Zealand: a retrospective cohort study.

OBJECTIVES: To assess the validity of an International Classification of Diseases (ICD) code based definition of non-fatal head trauma caused by child abuse (abusive head trauma) for population surveillance in New Zealand. DESIGN: A retrospective cohort study of hospital inpatient records. SETTING: A tertiary children's hospital in Auckland, New Zealand. PARTICIPANTS: 1731 children less than 5 years of age who were discharged after a non-fatal head trauma event over a 10-year period from 1 January 2010 to 31 December 2019. OUTCOME MEASURES: The outcome of assessment by the hospital's multidisciplinary child protection team (CPT) was compared with the outcome of ICD, Tenth Revision (ICD-10) discharge coding for non-fatal abusive head trauma (AHT). The ICD-10 code definition of AHT was derived from an ICD, Ninth Revision, Clinical Modification definition developed by the Centers for Disease Control, Atlanta, Georgia, which requires both a clinical diagnosis code and a cause-of-injury code. RESULTS: There were 1755 head trauma events with 117 determined as AHT by the CPT. The ICD-10 code definition had a sensitivity of 66.7% (95% CI 57.4 to 75.1) and specificity of 99.8% (95% CI 99.5 to 100). There were only three false positives but 39 false negatives, with 18 of the false negatives coded with X59 (exposure to unspecified factor). CONCLUSIONS: The ICD-10 code broad definition of AHT is a reasonable epidemiological tool for passive surveillance of AHT in New Zealand but it underestimates the incidence. Its performance could be improved by clear documentation of child protection conclusions in clinical notes, clarifying coding practice and removing the exclusion criteria from the definition.

Comparisons of characteristics and outcome between abusive head trauma and non-abusive head trauma in a pediatric intensive care unit.

BACKGROUND: Abusive head trauma (AHT) is the leading cause of death in infants with traumatic brain injury (TBI). Early recognition of AHT is important for improving outcomes, but it can be challenging due to its similar presentations with non-abusive head trauma (nAHT). This study aims to compare clinical presentations and outcomes between infants with AHT and nAHT, and to identify the risk factors for poor outcomes of AHT. METHODS: We retrospectively analyzed infants of TBI in our pediatric intensive care unit from January 2014 to December 2020. Clinical manifestations and outcomes were compared between patients with AHT and nAHT. Risk factors for poor outcomes in AHT patients were also analyzed. RESULTS: 60 patients were enrolled for this analysis, including 18 of AHT (30%) and 42 of nAHT (70%). Compared with those with nAHT, patients with AHT were more likely to have conscious change, seizures, limb weakness, and respiratory failure, but with a fewer incidence of skull fractures. Additionally, clinical outcomes of AHT patients were worse, with more cases undergoing neurosurgery, higher Pediatric Overall Performance Category score at discharge, and more anti-epileptic drug (AED) use after discharge. For AHT patients, conscious change is an independent risk factor for a composite poor outcome of mortality, ventilator dependence, or AED use (OR = 21.9, P = 0.04) CONCLUSION: AHT has a worse outcome than nAHT. Conscious change, seizures and limb weaknesses but not skull fractures are more common in AHT. Conscious change is both an early reminder of AHT and a risk factor for its poor outcomes.

Effectiveness of Wearable Protection Equipment for Seated Pedestrians.

This study used finite element models to investigate the efficacy of seated pedestrian protection equipment in vehicle impacts. The selected safety equipment, a lap belt, an airbag vest, and a bicycle helmet, were chosen to mitigate the underlying biomechanical causes of seated pedestrian injuries reported in the literature. The impact conditions were based on the three most dangerous impact scenarios from a previous seated pedestrian impact study. Serious injury (AIS 3+) risks were compared with and without protective equipment. A 50th percentile male occupant model and two generic vehicle models, the family car (FCR) and sports utility vehicle (SUV), were used to simulate vehicle collisions. Three impact conditions were run with every combination of protective equipment (n = 24). The helmet reduced head and brain injury risks from the vehicle-head and ground-head contacts. The airbag reduced the head injury risk in the FCR vehicle-head contact but increased the brain injury risks in the SUV impacts from increased whiplash. The lap belt increased head injury risks for both the FCR and the SUV impacts because it created a stronger FCR vehicle-head contact and SUV ground-head contact. When the belt and airbag were used together the head injury risks dramatically decreased because the pedestrian body impacted the ground arm or leg first and slowly rolled onto the ground which resulted in softer ground-head contacts and in two instances, no ground-head contact. Only the helmet proved effective in all impact conditions. Future testing must be completed before recommending the belt or airbag for seated pedestrians.