Vehicle-pedestrian Collisions Research Articles

Crosswalk Confusion

Traffic safety researchers have long argued that driver behavior outweighs physical elements (such as road design) as a causal factor in motor vehicle collisions. A fundamental causal component of pedestrian-vehicle collisions is also behavior: that of the driver and that of the pedestrian. One determinant of this behavior may be whether the driver, the pedestrian, or both understand the motor vehicle code, which demarcates the right-of-way in pedestrian-vehicle interactions. That is, inappropriate or unlawful behavior may occur because the law is not understood or is misunderstood. Previous studies have shown that drivers and pedestrians have a limited knowledge of pedestrian right-of-way laws. This research expands on these studies by specifically considering knowledge of right-of-way laws related to marked and unmarked crosswalks. Driver and pedestrian knowledge was assessed by the use of intercept surveys and focus groups conducted in the San Francisco Bay Area in California. The results confirm that a substantial level of confusion about pedestrian right-of-way laws exists. This confusion was exacerbated by intersections that had unstriped, or unmarked, crosswalks. The implications for engineering, education, and enforcement countermeasures in light of these findings are discussed; and areas for further research are proposed.

Influence of Age-Related Stature on the Frequency of Body Region Injury and Overall Injury Severity in Child Pedestrian Casualties

Objective. The current study aims to evaluate the influence of age-related stature on the frequency of body region injury and overall injury severity in children involved in pedestrian versus motor vehicle collisions (PMVCs). Methods. A trauma registry including the coded injuries sustained by 1,590 1- to 15-year-old pedestrian casualties treated at a level-one trauma center was categorized by stature-related age (1–3, 4–6, 7–9, 10–12, and 13–15 years) and body region (head and face, neck, thorax, abdomen and pelvic content, thoracic and lumbar spine, upper extremities, pelvis, and lower extremities). The lower extremity category was further divided into three sub-structures (thigh, leg, and knee). For each age group and body region/sub-structure the proportion of casualties with at least one injury was then determined at given Abbreviated Injury Scale (AIS) severity levels. In addition, the average and distribution of the Maximum Abbreviated Injury Score (MAIS) and the average Injury Severity Score (ISS) were determined for each age group. The calculated proportions, averages, and distributions were then compared between age groups using appropriate significance tests. Results. The overall outcome showed relatively minor variation between age groups, with the average ± SD MAIS and ISS ranging from 2.3 ± 0.9 to 2.5 ± 1.0 and 8.2 ± 7.2 to 9.4 ± 8.9, respectively. The subjects in the 1- to 3-year-old age group were more likely to sustain injury to the head, face, and torso regions than the older subjects. The frequency of AIS 2+ lower extremity injury was approximately 20% in the 1- to 3-year-old group, but was twice as high in the 4- to 12-years age range and 2.5 times as high in the oldest age group. The frequency of femur fracture increased from 10% in the youngest group to 26% in the 4- to 6-year-old group and then declined to 14% in the 10- to 15-years age range. The frequency of tibia/fibula fracture increased monotonically with group age from 8% in the 1- to 3-year-old group to 31% in the 13- to 15-year-old group. Conclusions. While the overall outcome of child pedestrian casualties appears to be relatively constant across the pediatric stature range considered (∼74–170 cm), subject height seems to affect the frequency of injury to individual body regions, including the thorax and lower extremities. This suggests that vehicle safety designers need not only account for the difference in injury patterns between adult and pediatric pedestrian casualties, but also for the variation within the pediatric group.

Childhood injuries from motor vehicle–pedestrian collisions in Wuhan, The People's Republic of China

To examine motor vehicle-pedestrian collision injuries resulting in hospitalisation among children admitted into Wuhan Children's Hospital, The People's Republic of China. From the 1993 to 2004 inpatient data of Wuhan Children's Hospital, we identified injury cases from motor vehicle traffic crashes among children aged 18 years or less using the discharge diagnosis defined by the International Classification of Diseases, Ninth Revision, Clinical Modification (ICD-9-CM). We examined characteristics of injuries from motor vehicle traffic crashes (ICD-9-CM = E810-E819) and then calculated the proportion of injuries from motor vehicle-pedestrian collisions (ICD-9-CM = E814) among all hospitalisations for childhood injuries (ICD-9-CM = 800-959). The trend of injuries from motor vehicle-pedestrian collisions from 1993 to 2004 was described. Of the 12,939 injuries resulting in hospitalisation among children admitted into Wuhan Children's Hospital during 1993-2004, a total of 528 injuries were caused by motor vehicle traffic crashes. The majority of the injured children in motor vehicle traffic crashes were males (59.3%). In comparison with other traffic injuries, a higher proportion of motor vehicle-pedestrian collisions occurred among children aged 12-15 years. Motor vehicle-pedestrian collision injuries resulted in significantly longer lengths of stay in the hospital than other motor vehicle traffic injuries (19.4 days versus 14.3 days, respectively; t-test = 2.59, p-value < 0.05). The percentage of motor vehicle-pedestrian collision injuries among all hospitalisations for childhood injuries increased significantly from 1.6% (95% confidence interval [CI] = 1.2-2.1) in 1993 to 3.1% (95% CI = 2.7-3.6) in 2004 (p < 0.05). Hospitalisations for injuries from motor vehicle-pedestrian collisions at this large children's hospital increased significantly in the past decade. These data underscore the need for additional research and a major concerted effort to prevent motor vehicle-pedestrian collisions among children in China.

Feedback Approach for Determining Parameters of Vehicle Safety Regulation on Pedestrian Protection

In recent years, significant efforts have been made around the world to establish an internationally agreed-upon vehicle safety regulation that will reduce pedestrian casualties in pedestrian–vehicle collisions. One of the key issues in putting together the regulation is how to select effectively the parameter values that will be associated with it. This study develops an integrated feedback-based decision-making procedure for determining parameter values of the vehicle safety regulation. The regulation aims to protect pedestrian heads in pedestrian–vehicle collisions. Detailed data analyses from both actual accidents and simulations were conducted to derive parameters that result in technically and economically feasible regulation. A set of parameters representing the characteristics of pedestrian accidents and vehicles in South Korea is presented as the outcome of this study. The major contribution of this study is in supporting the establishment of South Korean vehicle safety regulations that would lead to the development of advanced vehicular technologies to reduce the severity of pedestrian injuries.

Feedback Approach for Determining Parameters of Vehicle Safety Regulation on Pedestrian Protection: South Korean Case Study

In recent years, significant efforts have been made around the world to establish an internationally agreed-upon vehicle safety regulation that will reduce pedestrian casualties in pedestrian-vehicle collisions. One of the key issues in putting together the regulation is how to select effectively the parameter values that will be associated with it. This study develops an integrated feedback-based decision-making procedure for determining parameter values of the vehicle safety regulation. The regulation aims to protect pedestrian heads in pedestrian-vehicle collisions. Detailed data analyses from both actual accidents and simulations were conducted to derive parameters that result in technically and economically feasible regulation. A set of parameters representing the characteristics of pedestrian accidents and vehicles in South Korea is presented as the outcome of this study. The major contribution of this study is in supporting the establishment of South Korean vehicle safety regulations that would lea...

Case study of a low-velocity pedestrian accident

A case study of a minitruck-to-pedestrian accident is presented in which the pedestrian was impacted by the minitruckas corner at a low velocity. Although the pedestrian was struck on his back, he landed on his back on the ground. There were two arc-shaped sites of subcutaneous haemorrhage indicated on his back. On the basis of an animal experiment, it was shown that haemorrhage in the soft tissue depends on the impactor shape. By detailed examination of the subcutaneous haemorrhage sites on the pedestrian's back, the markings reflected the shape and dimensions of the truck's windshield wiper. A mathematical simulation and an experiment involving a minitruck collision into a pedestrian dummy were conducted to determine the kinematics when a pedestrian is impacted by the corner of a truck. It was shown that the pedestrian rotated around his vertical axis according to the curvature of the truck corner. Although this is a case study, this accident provides useful knowledge for research on vehicle-pedestrian collisions.

Safety in Numbers

This paper adds material to the ongoing body of literature exploring the effect of pedestrian volume on safety for pedestrians. Observed and existing data for 247 intersections in Oakland, California, were used to model the effect of pedestrian volume on the number and rate (number of collisions per pedestrians) of vehicle–pedestrian collisions at or near these intersections. The study used a data set containing pedestrian collisions, average annual pedestrian volume, average annual vehicle volume, and other intersection characteristics. Estimates of the model parameters show that the number of pedestrian collisions increases more slowly than the number of pedestrians; that is, the collision rate decreases as the number of pedestrians increases, consistent with previous studies by Leden and Jacobsen. Specifically, a doubling of the number of pedestrians (increase of 100%) is associated with only a 52% increase in the number of vehicle–pedestrian collisions, with the corresponding rate decreasing by about 24%. If further research shows this association to be causal, and not due to variation in intersection characteristics or selection factors involving pedestrian choice, the implications for policy and planning involving pedestrians are substantial.

Safety in Numbers: Data from Oakland, California

This paper adds material to the ongoing body of literature exploring the effect of pedestrian volume on safety for pedestrians. Observed and existing data for 247 intersections in Oakland, California, were used to model the effect of pedestrian volume on the number and rate (number of collisions per pedestrians) of vehicle—pedestrian collisions at or near these intersections. The study used a data set containing pedestrian collisions, average annual pedestrian volume, average annual vehicle volume, and other intersection characteristics. Estimates of the model parameters show that the number of pedestrian collisions increases more slowly than the number of pedestrians; that is, the collision rate decreases as the number of pedestrians increases, consistent with previous studies by Leden and Jacobsen. Specifically, a doubling of the number of pedestrians (increase of 100%) is associated with only a 52% increase in the number of vehicle-pedestrian collisions, with the corresponding rate decreasing by about ...

Predicting the effect of various ISA penetration grades on pedestrian safety by simulation

Intelligent speed adaption (ISA) is one type of vehicle-based intelligent transportation systems (ITS), which warns and regulates driving speed according to the speed limits of the roads. Early field studies showed that ISA could reduce general mean speed levels and their variances in different road environments. This paper studies the effects of various ISA penetration grades on pedestrian safety in a single lane road. A microscopic traffic simulation tool, TPMA, was further developed and used to implement different ISA penetration grades. Momentary spot speed and traffic flow data are first logged in the traffic simulation for later prediction of pedestrian safety. Then a hypothetical vehicle–pedestrian collision model is extended from early researches in order to estimate two safety indicators: probability of collision, and risk of death. Finally, Monte Carlo method is applied iteratively to compute those safety indices. The computational result shows that raising ISA penetration in traffic flow will reduce both the probability of mid-block collision between vehicle and pedestrian and the risk of death in the collision accidents. Furthermore, the decrease of the risk of death will be more prominent than that of the collision probability according to this method.

Vehicle-pedestrian collisions: Validated models for pedestrian impact and projection

The most important factor in pedestrian injuries from vehicle collisions is the impact velocity. In cases where the impact configuration can be ascertained, the most common method now used to determine vehicle speed involves the pedestrian projection distance. The more traditional method of using tyre brake marks is losing applicability as ABS braking systems become more common. The two most common impact configurations are wrap projection and forward projection, these being determined by the vehicle/pedestrian geometry and the initial conditions of the impact. In this paper, two models are presented for pedestrian forward and wrap projection impacts. These models are predicated on separating the total projection distance into the individual projection distances occurring during three principal phases of the collision. The models are novel as they use a rigid single-segment body representation of the pedestrian, include explicit modelling of the impact phase, and also allow for uncertainty in the input parameters. Published data are used to provide distributions for the input variables such as pedestrian and vehicle masses, etc. The model predictions of impact speed from overall projection distance are validated by comparison with real-world accident data.

Review of injury biomechanics in car-pedestrian collisions

The aim of this paper is to survey the state-of-the-art of injury biomechanics in vehicle-pedestrian collisions, including the dynamic responses, injury mechanisms, tolerance levels, injury criteria and parameters that have relevance for injuries in different loading conditions. A condensed overview is given based on the published and ongoing studies in pedestrian injury biomechanics. The need for future research on pedestrian injury prevention is presented.

540 歩行者事故時の衝撃条件と下肢傷害の関係

540 歩行者事故時の衝撃条件と下肢傷害の関係

Space Syntax: Innovative Pedestrian Volume Modeling Tool for Pedestrian Safety

An innovative pedestrian modeling technique known as Space Syntax is described. The technique was used to create estimates of pedestrian volumes for the city of Oakland, California. Pedestrian exposure rates were calculated, and a relative risk index for the city's first pedestrian master plan was created with those estimates. A major challenge facing planners, transportation engineers, and pedestrian-safety advocates is the lack of detailed, high-quality pedestrian-exposure data. Exposure is defined as the rate of contact with a potentially harmful agent or event. Pedestrian exposure is therefore defined as the rate of pedestrian contact with potentially harmful situations involving moving vehicles (e.g., crossing an intersection). Pedestrian risk is defined as the probability that a pedestrian-vehicle collision will occur, based on the rate of exposure. To estimate exposure, pedestrian volume measurements must be made, but such measurements are not easily obtainable. In the absence of accurate exposure data, pedestrian-safety decisions are often made by estimation, rule of thumb, or political influence and result in mixed and potentially less effective outcomes. The value of the Space Syntax volume-modeling approach for generating estimates of pedestrian exposure is explored with the city of Oakland as a case study. The method's theoretical background, data requirements, implementation, and results are discussed. It is suggested that the output of the model—citywide pedestrian volume estimates—is useful to pedestrians, planners, and transportation engineers. The value of the pedestrian-exposure concept for the planning professional is discussed.

Finite Element Analysis of Knee Injury Risks in Car-to-Pedestrian Impacts

In vehicle–pedestrian collisions, lower extremities of pedestrians are frequently injured by vehicle front structures. In this study, a finite element (FE) model of THUMS (total human model for safety) was modified in order to assess injuries to a pedestrian lower extremity. Dynamic impact responses of the knee joint of the FE model were validated on the basis of data from the literature. Since in real-world accidents, the vehicle bumper can impact the lower extremities in various situations, the relations between lower extremity injury risk and impact conditions, such as between impact location, angle, and impactor stiffness, were analyzed. The FE simulation demonstrated that the motion of the lower extremity may be classified into a contact effect of the impactor and an inertia effect from a thigh or leg. In the contact phase, the stress of the bone is high in the area contacted by the impactor, which can cause fracture. Thus, in this phase the impactor stiffness affects the fracture risk of bone. In the inertia phase, the behavior of the lower extremity depends on the impact locations and angles, and the knee ligament forces become high according to the lower extremity behavior. The force of the collateral ligament is high compared with other knee ligaments, due to knee valgus motions in vehicle-pedestrian collisions.

Impact throw model for vehicle-pedestrian collision reconstruction

Impact throw model for vehicle-pedestrian collision reconstruction

Impact throw model for vehicle-pedestrian collision reconstruction

A planar model for the mechanics of a vehicle-pedestrian collision is presented, analysed and compared with experimental data. It takes into account the significant physical parameters of wrap and forward projection collisions and is suitable for solution using mathematics software or spreadsheets. Parameters related to the pedestrian and taken into account include horizontal distance travelled between primary and secondary impacts with the vehicle, launch angle, centre-of-gravity height at launch, the relative forward speed of the pedestrian to the car at launch, distance from launch to a ground impact, distance from ground impact to rest and pedestrian-ground drag factor. Vehicle and roadway parameters include post-impact, constant velocity vehicle travel distance, continued vehicle travel distance to rest with uniform deceleration and relative distance between rest positions of vehicle and pedestrian. The model is presented in two forms. The first relates the throw distance to the initial vehicle speed. The second, intended for reconstruction, relates the vehicle speed to the pedestrian throw distance. The first form is used as means of comparison of the model with selected sets of experimental data taken from the current literature, including a variational study using Monte Carlo simulation. The second (reconstruction) form is derived analytically not empirically and the parameters have physical interpretations. In order to obtain parameter values, direct calculation or the method of least squares can be used. A comparison of the reconstruction model with results of other reconstruction models is presented.

Effects of acute injury characteristics on neuropsychological status and vocational outcome following mild traumatic brain injury

Despite recent attempts to define acute injury characteristics of mild traumatic brain injury (MTBI), neuropsychological outcome is often unpredictable. One hundred MTBI cases were prospectively collected, which were consecutive referrals to a concussion clinic, and the roles of various acute neurologic variables were examined in relation to neuropsychological status and vocational outcome. Significant differences were found between subgroups of patients classified by (1) mechanism of injury (i.e. acceleration/deceleration trauma in which the head strikes an object (HSO) versus acceleration/ deceleration trauma in which the head does not strike an object (HNSO) versus trauma in which an object strikes the head (OSH), and (2) type of injury (i.e. motor vehicle collision, fall, assault, motor vehicle-pedestrian collision, falling object, sports/recreation). There was no difference, with respect to neuropsychological status or vocational outcome, between patients who had positive findings on computerized tomography (CT) versus those who were CT negative. Additionally, there was no difference between patients who had suffered brief loss of consciousness (LOC) and those without LOC. These findings suggest that selective acute injury characteristics may be used to classify subtypes of MTBI patients.

Method for Estimating Effect of Traffic Volume and Speed on Pedestrian Safety for Residential Streets

When local governments find that the demand for traffic-calming measures exceeds their available resources, it may be necessary to select the most needful or most promising projects. Since pedestrian-vehicle collisions tend to be rare on local streets, it will usually not be possible to use accident counts to identify high-hazard locations. A deterministic model of a collision between a pedestrian and a vehicle is described and then some of the model’s variables are allowed to be random. The probability of a collision can then be evaluated as the probability of obtaining a set of variable values leading to a collision. Both parametric and non-parametric methods are described and illustrated, including an example in which estimates of the collision probability and the probability distribution of vehicle collision speeds are used to identify promising sites for traffic calming. The methods can be used for any location where an analyst has vehicle spot speed and traffic count data and is able to specify reasonable values for the other model variables.

BRAIN INJURY PATTERNS IN FATALLY INJURED PEDESTRIANS

To study the relationship between the severity of impact to the head and the severity and distribution of injury to the brain in fatally injured pedestrians, events in vehicle-pedestrian collisions were reconstructed to determine the peak linear and angular acceleration sustained by the pedestrians' heads. The nature and distribution of injuries to the brain were determined by neuropathologic examination of coronal sections of the brain. Study of 13 cases with occipital impacts and 18 with lateral impacts showed that the brain appeared to be more susceptible to injury from lateral impacts. The frontal and temporal regions appeared to be more susceptible to injury at low accelerations in occipital impacts, providing an explanation for "coup" and "contrecoup" injuries. For occipital impacts, a positive relationship was found between linear acceleration and the extent of injury to the brain, suggesting that there was a threshold for observable and concussive brain injury at about 1500 m/s2 peak linear acceleration. These findings are important for the development of measures for preventing brain injuries.

Skull Fractures in Fatalities Due to Motor Vehicle Collisions

A retrospective analysis of 89 fatalities with skull fracture resulting from motor vehicle-pedestrian and various single passenger car frontal, side, rear and rollover collisions was done. Passenger compartment intrusion and occupant ejection were responsible for most, but not all, cranial fractures occurring in impacted motor vehicles. Victims of frontal collisions usually were unrestrained; however, a majority of individuals in cars hit by heavy trucks were wearing seatbelts. Vehicles involved in frontal crashes had crush profiles reflecting a barrier equivalent velocity (BEV) of at least 50 km/h (about 30/mph). In side impacts, most ejected occupants were unrestrained, whereas many of those intruded upon were belted. The minimum BEV calculated in these collisions approached 20 km/h (12 mph). The observation of a skull fracture integrated with accident investigation (that is, determination of head contacts) was useful in the reconstruction of various collisions. Skull fracture patterns, as documented by autopsy, reflected certain kinematic trajectories described in motor vehicle-pedestrian frontal collisions.