Modelling of dust lifting process behind propagating shock wave

Dust dispersion from a layer is a complicated problem, which has not been completely solved yet, especially if an Eulerian–Eulerian approach has to be used to model the two-phase dusty flow. In previous investigation, a phenomenological model of the dust dispersion process from a layer was developed, but the evaluation of the model revealed some weaknesses. In the current paper, the model of the dust dispersion process was presented and three improvements of the model were studied: Saffman force, Magnus force and particles collisions. The implementation of Magnus and Saffman forces into the code did not improve the numerical results and it was shown that it had very little influence on the dust lifting process, in case the phenomenological model of the layer is used. Some explanations were proposed in the paper. Besides, an empirical model of particles collisions was also added to the code and its influence on the results was studied. It was shown that the particles collisions model improved the obtained results, but further modifications are to be studied in the future.     

Effects of vehicle impact velocity, vehicle front-end shapes on pedestrian injury risk

Objective: This study aimed at investigating the effects of vehicle impact velocity, vehicle front-end shape, and pedestrian size on injury risk to pedestrians in collisions with passenger vehicles with various frontal shapes. Method: A series of parametric studies was carried out using 2 total human model for safety (THUMS) pedestrian models (177 and 165?cm) and 4 vehicle finite element (FE) models with different front-end shapes (medium-size sedan, minicar, one-box vehicle, and sport utility vehicle [SUV]). The effects of the impact velocity on pedestrian injury risk were analyzed at velocities of 20, 30, 40, and 50?km/h. The dynamic response of the pedestrian was investigated, and the injury risk to the head, chest, pelvis, and lower extremities was compared in terms of the injury parameters head injury criteria (HIC), chest deflection, and von Mises stress distribution of the rib cage, pelvis force, and bending moment diagram of the lower extremities. Result: Vehicle impact velocity has the most significant influence on injury severity for adult pedestrians. All injury parameters can be reduced in severity by decreasing vehicle impact velocities. The head and lower extremities are at greater risk of injury in medium-size sedan and SUV collisions. The chest injury risk was particularly high in one-box vehicle impacts. The fracture risk of the pelvis was also high in one-box vehicle and SUV collisions. In minicar collisions, the injury risk was the smallest if the head did not make contact with the A-pillar. Conclusion: The vehicle impact velocity and vehicle front-end shape are 2 dominant factors that influence the pedestrian kinematics and injury severity. A significant reduction of all injuries can be achieved for all vehicle types when the vehicle impact velocity is less than 30?km/h. Vehicle designs consisting of a short front-end and a wide windshield area can protect pedestrians from fatalities. The results also could be valuable in the design of a pedestrian-friendly vehicle front-end shape. [Supplementary materials are available for this article. Go to the publisher's online edition of Traffic Injury Prevention for the following free supplemental resource: Head impact conditions and injury parameters in four-type vehicle collisions and validation result of the finite element model of one-box vehicle and minicar. ].     

Modeling the probability of freeway lane-changing collision occurrence considering intervehicle interaction

Objective: To better capture the relationships between lane-changing collisions and explanatory variables, a microscopic model is developed for freeway lane-changing collisions based on the interactions between lane-changing vehicles.

Methods: The model applies an intervehicle interaction structure to account for the occurrence mechanism of lane-changing collisions. The occurrence mechanism can be described as the failure of a vehicle driver of an adjacent lane in avoiding the lane-changing vehicle, which disturbs the smooth movement of the adjacent lane vehicle and requires the driver's brake action to avoid an angle collision. This model is examined using data collected from freeways in Washington State during 2010 to 2011 and validated using lane-changing collision data for the SR 520 freeway.

Results: The findings of this study show that generalized truck percentage has a significant decreasing effect on lane-changing collision risk, whereas average spacing and several roadway characteristics have significant increasing effects. The frequency of slight collisions during peak hours is higher than that during off-peak hours. Young female drivers are more likely to be involved in collisions during lane-changing than young male drivers, but the result for senior drivers is opposite, with older male drivers having a higher probability of lane-changing collisions than female drivers in the same age group.

Conclusion: The process of lane-changing collisions is a complicated maneuver. Truck percentage, average spacing, and good roadway characteristics, such as straight and level segment, in the target lane have a significant effect on the occurrence of lane-changing collisions. Age and gender are also 2 important factors contributing to the relationship between lane-changing collisions and explanatory variables.     

Variations in occupant response with seat belt slack and anchor location during moderate frontal impacts

Both seat belt slack and anchor location are known to affect occupant excursion during high-speed frontal collisions, but their effects have not been studied at moderate collision severities. The goal of this study was to quantify how seat belt slack and anchor location affect occupant kinematics and kinetics in moderate severity frontal collisions. A Hybrid III 50th percentile male dummy was seated on a programmable sled and exposed to frontal collisions with a speed change of 17.5 km/h. The seat belt was adjusted either snugly or with 10 cm slack (distributed 60/40 between the shoulder and lap portions) and the anchor location was varied by adjusting the seat position either fully forward or rearward (seat travel = 13 cm). Accelerations and displacements of the head, T1 and pelvis were measured in the sagittal plane. Upper neck loads and knee displacements were also measured. Five trials were performed for each of the four combinations of belt adjustment (snug, slack) and anchor location (seat forward, seat rearward). For each trial, kinematic and kinetic response peaks were determined and then compared across conditions using ANOVAs. Peak displacements, accelerations and loads varied significantly with both seat belt slack and anchor location. Seat belt slack affected more parameters and had a larger effect than anchor location on most peak response parameters. Head displacements increased a similar amount between the snug/slack belt conditions and the rearward/forward anchor locations. Overall, horizontal head displacements increased from 23.8 cm in the snug-belt, rearward-anchor configuration to 33.9 cm in the slack-belt, forward-anchor configuration. These results demonstrated that analyses of occupant displacements, accelerations and loads during moderate frontal impacts should consider potential sources of seat belt slack and account for differences in seat belt anchor locations.     

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.     

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.     

Ecology of player-to-player contact in boys' youth soccer play

INTRODUCTION: Youth soccer (football) injuries occur for a wide range of reasons, but the most frequent cause of injury is via player-to-player contact. This study was designed to study the ecology of collisions between players during youth soccer play. METHOD: Six teams of 11- and 12-year-old male players were followed over the course of a full season. Games were videotaped and reviewed to address three primary questions: how frequently do player-to-player collisions occur; when and where on the field do those collisions occur; and what is the rate of falls and injuries as a result of player-to-player contact. RESULTS: A total of 1,279 player-to-player collisions was observed, or an average of 65.59 collisions per game. Nearly half of the observed collisions resulted in one or both players falling to the ground, and about one-tenth resulted in the referee calling a foul, but very few of the collisions (less than 1%) resulted in an injury. Collisions occurred relatively consistently throughout the games, no matter what the score was. They occurred most frequently in the midfield area, when the ball was on or near the ground, and when players were attempting to retrieve a loose, uncontrolled ball. CONCLUSIONS: Results are discussed with respect to implications for injury prevention.     

AEB effectiveness evaluation based on car-to-cyclist accident reconstructions using video of drive recorder

Objective: Though autonomous emergency braking (AEB) systems for car-to-cyclist collisions have been under development, an estimate of the benefit of AEB systems based on an analysis of accident data is needed for further enhancing their development. Compared to the data available from in-depth accident data files, data provided by drive recorders can be used to reconstruct car-to-cyclist collisions with greater accuracy because the position of cyclists can be observed from the videos. In this study, using data from drive recorders, the performance and limitations of AEB systems were investigated.

Method: Data of drive recorders involving taxi-to-cyclist collisions were collected. Using the images collected from the drive recorders of those taxis, 40 cases of 90° car-to-cyclist intersection collisions were reconstructed using PC-Crash. Then, the collisions were reconstructed again utilizing car models with AEB systems installed while changing the sensor’s field of view (FOV) and the delay time of initiating vehicle deceleration.

Results: The angle of FOV has a significant influence on avoiding car-to-cyclist collisions. Using a 50° FOV with a braking delay time of 0.5?s resulted in avoiding 6 collisions, and using a 90° FOV resulted in avoiding an additional 14 collisions. Even when installing an ideal AEB system providing 360° FOV and no delay time for braking, 8 collisions were not avoided, though the impact velocities were reduced for all of these remaining collisions. These collisions were caused by the cyclists’ sudden appearance in front of cars, and the time-to-collision (TTC) when the cyclists appeared was less than 0.9?s.

Conclusion: The AEB systems were effective for mitigating collisions that occurred due to driver perception delay. Because cyclists have a traveling velocity, a wide-angle FOV is effective for reduction of car-to-cyclist intersection collisions. The reduction of delay time in braking can reduce the number of collisions that are close to the braking performance limit. The collisions that remained even with an ideal AEB system in the PC-Crash simulation indicate that such collisions could still occur for autonomous cars if the traffic environment does not change.     

Alignment of the Lumbar Vertebrae in a Driving Posture

The purpose of this study was to define the anatomical arrangement of the lumbar spine in the mid-body sagittal plane of a human volunteer while in three postures: a driving posture; full flexion; and full extension. Radiographic images of the lumbar spine were made of a 33-year old 50th percentile male subject seated in a comfortable driving posture. Additional radiographs were made of the lumbar spine while the subject was postured in full voluntary flexion, and full voluntary extension. Anterior and posterior mid-sagittal vertebral endplate positions were plotted on an x-y coordinate system for each posture. Anterior and posterior disk thicknesses, and the positions of the centers of each vertebra were numerically determined using information from the plots. Disk thicknesses were then graphed and comparisons made for each posture. The arrangements of the centers of vertebrae were graphed and compared for the three different postures. The arrangement of the lumbar vertebrae tended toward that of full voluntary flexion while the subject was in a normal driving posture. Anterior disk thickness was a sensitive indicator of posture, while posterior disk thickness was not. While in a driving posture, the lower back approximated a straight-line that was nearly parallel to the seat back axis. The observations support those of an earlier study. Since soft tissue spinal elements can only be damaged by applying tensile forces in excess of their tolerance, the anterior elements of the lumbar spine would not be directly threatened in low velocity frontal collisions, since anterior elements would be in relative compression. Tension injury to the anterior structures as a result of a rear-end collision would first require reversing the preimpact conditions imposed by the normal driving posture. Tension injury to the posterior spinal elements resulting from low velocity rear-end collisions would be unlikely since axial compression loading would also diminish tension stress in posterior soft tissue structures. Any compression injury to posterior elements resulting from rear-end collisions would first require reversing the pre-impact conditions imposed by the normal driving posture.     

Whether conversion and weather matter to roundabout safety

IntroductionRoundabouts, as a form of intersection traffic control, are being constructed increasingly because of their promise to improve both efficiency and safety. However, roundabout performance varies from one context to another; and information on their performance during inclement weather is limited.MethodsTo evaluate the safety effects of converting signal-controlled intersections to modern roundabouts in a region that historically was unfamiliar with this type of traffic control, an empirical Bayes approach was used to analyze. Second, to examine the potential effects of rainfall on roundabout safety, a matched-pair approach was used to compare risk estimates of collision occurrence at roundabouts and signalized intersections under inclement weather conditions.ResultsRoundabout installation is shown as an effective safety intervention for serious collisions since conversion from signalized intersections to roundabouts translates into an overall 20% reduction in the occurrence of injury/fatal collisions. However, roundabouts witnessed more property-damage collisions than what would have been expected had the conversion not occurred. With respect to weather, there is no evidence of a statistically significant increase in crashes on days with rainfall relative to good weather conditions for roundabouts, whereas there is evidence of such an increase in crash risk estimated to be 4% to 22% for signalized intersections.ConclusionsWhile injury collisions are consistently found to be lower at intersections that have been converted from signalized intersections to roundabouts, the same is not always that case for property-damage collisions, suggesting that drivers need time to adjust. In terms of weather, the evidence in this paper shows that roundabouts show less sensitivity to rainy conditions than signalized intersections.Practical applicationsThe trade-offs between design, operation, and safety should be considered carefully when planning a new roundabout. More research is required on the specific problems users experience with roundabouts and the effectiveness of public education programs.     

Comparison of mid-block and intersection-related left turn collisions

OBJECTIVES: To evaluate the factors that might influence an occupant's injury severity during a left turn movement. METHODS: We used the National Automotive Sampling System Crashworthiness Data System (1995-2005) to compare crash characteristics and injury outcome between intersection and midblock left turn collisions. RESULTS: A total of 7,396 collisions were evaluated. Traffic control devices were present in 82% of intersection and 10% of mid-block collisions. After adjustment for potential confounding variables, drivers' injury severity was not significantly associated with the crash location. However, front seat passengers in mid-block collisions had 72% higher odds of experiencing an injury with injury severity score > or =9 (odds ratio: 1.72, 95% confidence interval: 1.09-2.69). Our analysis did not show that drivers or passengers in larger vehicles, e.g., sport utility vehicles and mini-vans, were at lower risk of more severe injuries in comparison to the car occupants in sedans. CONCLUSION: We found that in comparison to intersection-related left turn collisions, mid-block crashes are associated with more severe injuries for front seat passengers. Furthermore, size of the turning vehicle was not significantly associated with injury severity for drivers or front seat passengers.     

Variability in vehicle and dummy responses in rear-end collisions

OBJECTIVE: The objective of this study was to quantify the occupant response variability due to differences in vehicle and seat design in low-speed rear-end collisions. METHODS: Occupant response variability was quantified using a BioRID dummy exposed to rear-end collisions in 20 different vehicles. Vehicles were rolled rearward into a rigid barrier at 8 km/h and the dynamic responses of the vehicle and dummy were measured with the head restraint adjusted to the up most position. In vehicles not damaged by this collision, additional tests were conducted with the head restraint down and at different impact speeds. RESULTS: Despite a coefficient of variation (COV) of less than 2% for the impact speed of the initial 8 km/h tests, the vehicle response parameters (speed change, acceleration, restitution, bumper force) had COVs of 7 to 23% and the dummy response parameters (head and T1 kinematics, neck loads, NIC, N(ij) and N(km)) had COVs of 14 to 52%. In five vehicles tested multiple times, a head restraint in the down position significantly increased the peak magnitude of many dummy kinematic and kinetic response parameters. Peak head kinematics and neck kinetics generally varied linearly with head restraint back set and height, although the neck reaction moment reversed and increased considerably if the dummy's head wrapped onto the top of the head restraint. CONCLUSIONS: The results of this study support the proposition that the vehicle, seat, and head restraint are a safety system and that the design of vehicle bumpers and seats/head restraint should be considered together to maximize the potential reduction in whiplash injuries.     

独塔自锚式悬索桥吊索力影响参数敏感性分析*

为了解成桥吊索力对构件刚度、索鞍位置、温度、吊索张拉力等参数的敏感性，保证自锚式悬索桥体系转换能够安全顺利地完成，以天水市罗家沟大桥为工程背景，采用解析法修正空缆线形、有限元法模拟施工过程，分析张拉前参数和张拉过程参数变化对成桥吊索力的影响。结果表明:刚性吊索索力对吊索抗拉刚度变化敏感，在实际施工前可根据实测数据对吊索张拉力进行适当调整；中、长吊索索力对张拉时环境温度比较敏感，中、长吊索临近的吊索索力对第1轮吊索的张拉力偏差比较敏感，在实际施工时应采取相应的措施对张拉力予以精确控制；吊索力对散索鞍沿滑动面滑动的边界处理较敏感，应在有限元建模和施工时予以重视。     

Potential of a Precrash Lateral Occupant Movement in Side Collisions of (Electric) Minicars

Objective: In minicars, the survival space between the side structure and occupant is smaller than in conventional cars. This is an issue in side collisions. Therefore, in this article a solution is studied in which a lateral seat movement is imposed in the precrash phase. It generates a pre-acceleration and an initial velocity of the occupant, thus reducing the loads due to the side impact.

Methods: The assessment of the potential is done by numerical simulations and a full-vehicle crash test. The optimal parameters of the restraint system including the precrash movement, time-to-fire of head and side airbag, etc., are found using metamodel-based optimization methods by minimizing occupant loads according to European New Car Assessment Programme (Euro NCAP).

Results: The metamodel-based optimization approach is able to tune the restraint system parameters. The numerical simulations show a significant averaged reduction of 22.3% in occupant loads.

Conclusion: The results show that the lateral precrash occupant movement offers better occupant protection in side collisions.     

Acciphilia on the road: An analysis of severe collisions

Introduction

Although prior studies of road traffic accidents have found between-group differences in risk, little attention has been given to the encounter between drivers involved in severe collisions.

Method

The present study empirically evaluates two different possible causes of "social accidents," which are defined as collisions between two or more drivers where some faulty social interaction might be assumed, and which are the most prevalent cause of road injuries. The analyses use merged Israeli collision records from 1983 to 2004 with data from two national censuses, thus providing an unprecedented empirical basis to study the social foundations of car accidents. The data are used to adjudicate between two alternative hypotheses: the heterogeneity hypothesis (socially different drivers tend to collide) versus the homogeneity hypothesis (socially similar drivers tend to collide).

Results

Multivariate analyses provide preliminary support for the latter hypothesis. Given an accident, there are more collisions among drivers from the same broad educational group, and the factors that influence this correlation are independent of geography. The paper thus leads to the idea that severe collisions reflect a sociological or ecological process that is akin to acciphilia.

Impact on Industry

The preliminary findings suggest that variation between drivers may be preferable to similarity, since apparently there is a greater tendency toward collisions between similar drivers.     

Young driver risk in relation to parents' retrospective driving record

PROBLEM: Parents are an important potential influence on the driving safety of their children. This study examined the relationship of parental driving record on male and female offspring's at-fault collision risk. METHOD: Drivers aged 16-21 on the date of full licensure were selected from driver records and a matching process was used to identify putative parents in two-parent households. Poisson regression models were developed to predict at-fault collisions of male and female youth in the three years following full licensure from parents' at-fault collisions, speeding offenses, and other moving offenses in the four years prior to children's licensure. One set of models examined the relative risk associated with increasing numbers of maternal and paternal at-fault collisions and offenses. Other models examined the joint versus separate maternal and parental contributions. RESULTS: Controlling for region of residence, both mothers' and fathers' at-fault collisions were associated with an increased risk in both male and female youth at-fault collisions. Mothers' and fathers' speeding offenses were also associated with increased relative risk of at-fault collisions for both sons and daughters, while fathers' other moving offenses increased collision risk for sons but not daughters. DISCUSSION: Further research is required to identify how parental driving risk is transmitted to children. IMPACT ON INDUSTRY: (a) Parents of young children should be informed of their role in influencing their children's future driving risk; (b) The results identify risk factors that could be of interest to licensing authorities and the insurance industry.     

Effects of initial seated position in low speed rear-end impacts: a comparison with the TNO rear impact dummy (TRID) model

Injury-producing mechanisms associated with rear-end impact collision has remained a mystery not withstanding numerous investigations devoted to its scrutiny. Several criteria have been proposed to predict the injury-causing mechanism, but none have been universally accepted. The challenge lies in determining a set of testing procedures representative of real-world collisions, wherein the results obtained are not only the same as human testing, but remain consistent with various subjects and impact conditions. It is hypothesized that one of the most important considerations in the testing methodology is the effect of initial seated position (ISP) on occupant kinematics during a rear impact collision. This study involves two parts that evaluates the effects of ISP during rear-end impact. In the first part, head acceleration results of computer simulation using Hybrid III TNO rear impact dummy (TRID) are compared to physical impact testing (PIT) of humans. The second part focuses on the computer simulation using TRID to obtain different neck parameters such as NIC (Neck Injury Criterion), NIJ (Neck Injury Predictor), neck forces and moments to predict the level of neck injury such as whiplash associated disorder (WAD) during low speed rear-end impact. In PIT, a total of 17 rear-impact tests were conducted with a nominal 8-km/hour change in velocity to 5 subjects in four different seated positions comprising of a normal position (NP) and three out of positions (OOP). The first position was a NP, defined as torso against the seat back, looking straight ahead, hands on the steering wheel, and feet on the floor. The second position was a head flex position (HFP), defined as the normal position with head flexed forward approximately 20 degrees. The third position was a torso lean position (TLP), defined as the normal position with torso leaned forward approximately 10 degrees away from the seat back. Lastly, a torso lean head flex position (TLHFP), defined as the normal position with the head flexed forward approximately 20 degrees and torso leaned forward approximately 10 degrees. The head acceleration plots from PIT reveal that for the third and fourth positions (TLP and TLHFP) when the subject torso leaned forward, the peak head acceleration for the subject decreased and there was also a delay in reaching the peak. The Hybrid III-TRID anthropomorphic test dummy (ATD) was used in the same four different seated positions using computer simulation software MAthematical DYnamic MOdel (MADYMO 6.0) and the head acceleration results were compared to PIT. The comparison demonstrates that the Hybrid III-TRID ATD with MADYMO can be a reliable testing procedure during low-speed, rear-end impact for the four ISPs considered since the head acceleration plots deviated within the range of PIT head acceleration plots for different human subjects. This ensures that the second part of the study with neck injury using computer simulation results is a reliable testing procedure. It can be observed that MADYMO results have a greater error when compared to PIT when more than one OOP condition is employed as in TLHFP. All these observations would help in providing a tool to better understand the injury mechanisms and provide an accurate testing procedure for rear-end impact.     

Effect of novel divergence markings on conflict prevention regarding motorcycle-involved right turn accidents of mixed traffic flow

Introduction: In Taiwan, segregated traffic flow countermeasures have long been in place. Although these facilities have decreased the numbers of motorcycle left-turn collisions, right-angle collisions, and sideswipe collisions, they have also induced serious right-turn accidents. The purpose of this research was to evaluate an intervention intended to decrease conflicts and motorcycle-involved crashes. In this study, the reasons why the motorcycle accident rate is higher at intersections with slow lanes than at those without slow lanes are presented, and the theory of the self-explaining road was applied to create divergence markings for a mixed traffic flow environment. An intervention that guides motorcycles and cars into appropriate locations at intersections was applied to three intersection approaches. Method: The intervention effectiveness was evaluated by comparing the number of accidents at the intersections before and after the implementation of improvement measures. Moreover, video recordings were used to analyze the traffic distributions at the cross-sections of intersections. T-test was adopted to examine whether the traffic flows at the cross-sections of the intersections before and after the intervention were statistically different. In addition, this research applied the post-encroachment time (PET), the time between the first road user leaving the encroachment zone and the second road user arriving in it, to evaluate traffic conflicts. Finally, the PET and severity index between a straight-through motorcycle and a right-turn vehicle were analyzed. Results: PET increased by 3.2%–20.4%, and the rates of right-turn collisions, sideswipe collisions, and rear-end collisions decreased by 64.3%, 77.3%, and 61.5% respectively. Conclusions: Eliminating the slow traffic lane and setting divergence markings may not effectively cause vehicles in different driving directions to drive in the proper locations in the lanes. However, divergence markings both reduce the rate of right-turn collisions and decrease the incidence of sideswipe and rear-end collisions. Practical applications: The proposed design method may be a good design reference for countries having a high motorcycle density.     

Turning at intersections and pedestrian injuries

OBJECTIVE: To evaluate if precrash vehicle movement is associated with the severity of pedestrian injury. METHODS: We used comprehensive information on pedestrian, vehicle, and injury-related characteristics gathered in the Pedestrian Crash Data Study (PCDS), conducted by the National Highway Traffic Safety Administration (NHTSA) (1994-1998). The odds ratio of severe injuries (injury severity score >/= 15) and crash fatality rate for right- and left-turn collisions at intersection compared with straight vehicle movement were compared using a logistic regression model and taking into consideration the type of vehicle and age of the pedestrians as potential effect modifiers. Later we evaluated the intermediate effect of impact speed on the association by adding it to the logistic regression model. RESULTS: Of 255 collisions eligible for this analysis, the proportion of pedestrian hit during straight movement, right turns, and left turns were 48%, 32%, and 10%, respectively. Sixty percent of the pedestrians in left-turn crashes and 67% of them in right-turn collisions were hit from their left side. For straight movements the pedestrians were equally likely to be struck beginning from the left or right side of the street.After adjustment for pedestrian's age, vehicle movement was a significant predictor of severe injuries (p < 0.0001) and case fatality (p = 0.003). The association between vehicle precrash movement and severe injuries (p = 0.551) and case fatality (p = 0.912) vanished after adjusting for impact speed. This indicated that the observed association was probably the result of the difference in impact speed and not the precrash movement of the vehicle. CONCLUSION: Pedestrian safety interventions that aim at environmental modifications, such as crosswalk repositioning, might be the most efficient means in reducing right- or left-turn collisions at intersection, while pedestrians' behavioral modifications should be the priority for alleviating the magnitude of the collisions that happen in vehicles' straight movements.