Critical factors in fatal collisions of adult cyclists with automobiles

This article evaluates, by means of multivariate regression, critical factors influencing the collisions of motor vehicles with adult (over 17 years) cyclists that result in fatal injury of cyclists. The analysis is based on the database of the Traffic Police of Czech Republic from the time period 1995–2007. The results suggest that the most consequential categories of factors under study are: inappropriate driving speed of automobile; the head-on crash; and night-time traffic in places without streetlights. The cyclists’ faults are of most serious consequence on crossroads when cyclists deny the right of way. Males are more likely to suffer a fatal injury due to a collision with a car than females. The most vulnerable age group are cyclists above 65 years. A fatal injury of a cyclist is more often driver's fault than cyclist's (598 vs. 370).In order to reduce the fatal risk, it is recommended to separate the road traffic of motor vehicles from bicyclists in critical road-sections; or, at least, to reduce speed limits there.     

Visual assessment of pedestrian crashes

Of the numerous factors that play a role in fatal pedestrian collisions, the time of day, day of the week, and time of year can be significant determinants. More than 60% of all pedestrian collisions in 2007 occurred at night, despite the presumed decrease in both pedestrian and automobile exposure during the night. Although this trend is partially explained by factors such as fatigue and alcohol consumption, prior analysis of the Fatality Analysis Reporting System database suggests that pedestrian fatalities increase as light decreases after controlling for other factors.This study applies graphical cross-tabulation, a novel visual assessment approach, to explore the relationships among collision variables. The results reveal that twilight and the first hour of darkness typically observe the greatest frequency of pedestrian fatal collisions. These hours are not necessarily the most risky on a per mile travelled basis, however, because pedestrian volumes are often still high. Additional analysis is needed to quantify the extent to which pedestrian exposure (walking/crossing activity) in these time periods plays a role in pedestrian crash involvement. Weekly patterns of pedestrian fatal collisions vary by time of year due to the seasonal changes in sunset time. In December, collisions are concentrated around twilight and the first hour of darkness throughout the week while, in June, collisions are most heavily concentrated around twilight and the first hours of darkness on Friday and Saturday. Friday and Saturday nights in June may be the most dangerous times for pedestrians. Knowing when pedestrian risk is highest is critically important for formulating effective mitigation strategies and for efficiently investing safety funds. This applied visual approach is a helpful tool for researchers intending to communicate with policy-makers and to identify relationships that can then be tested with more sophisticated statistical tools.     

Assessment of hospital and police ascertainment of automobile versus childhood pedestrian and bicyclist collisions.

Information about automobile versus pedestrian or bicyclist collisions differ according to the source of collision ascertainment. Hospital records and police reports focus on different characteristics of a collision, which reflects differences in case finding as well as information regarding risk factors. Pedestrians and bicyclists 0-14 years of age who were involved in a motor vehicle collision in the city of Long Beach, CA, between January 1, 1992 and June 30, 1995, were included in the study. Police reports and medical records were used to identify cases. Police reports were found for 1,015 cases, and medical records identified 474 cases; 379 cases were common to both sources. A capture-recapture model was used to evaluate the degree of overlap between the two sources and to derive "ascertainment corrected" injury rates. The injury rate from combined sources was 333.5/100,000 children per year, the pedestrian injury rate was 210.6/100,000 children per year and the bicyclist injury rate was 122.9/100,000 children per year. The "ascertainment corrected" injury rate overall was 381.3/100,000 children per year, 233.0/100,000 for pedestrians and 153.9/100,000 children per year for bicyclists. Eighty percent of hospital-reported cases were captured in the police database, whereas only 37% of police-reported cases were captured by the hospital database. We found that hospital sources identified younger children, fewer bicyclists, more Asian and Hispanic children, and fewer African-American children when compared to police sources. For more comprehensive surveillance resulting in more accurate incidence rates and more complete information, it is better to use multiple sources of data.     

Motorcycle helmet type and the risk of head injury and neck injury during motorcycle collisions in California

The use of novelty motorcycle helmets is often prompted by beliefs that wearing a standard helmet can contribute to neck injury during traffic collisions. The goal of this analysis was to examine the association between helmet type and neck injury risk and the association between helmet type and head injury. Data were collected during the investigation of motorcycle collisions of any injury severity by the California Highway Patrol (CHP) and 83 local law enforcement agencies in California between June 2012 and July 2013. We estimated head injury and neck injury risk ratios from data on 7051 collision-involved motorcyclists using log-binomial regression. Helmet type was strongly associated with head injury occurrence but was not associated with the occurrence of neck injury. Rider age, rider alcohol use, and motorcycle speed were strong, positive predictors of both head and neck injury. Interventions to improve motorcycle helmet choice and to counteract misplaced concerns surrounding neck injury risk are likely to lead to reductions in head injury, brain injury, and death.     

Limits for survivability in frontal collisions: theory and real-life data combined

The limits for survivability in vehicle frontal collisions are unknown. This paper proposes a new hypothesis that occupant risk in frontal collisions is due to both inertial and crushing injuries and that the limits of survivability in frontal collisions are principally due to the complete crushing of vehicles at high DeltaV's. Analysis of the NASS data for the period 1982-1991 for AIS3+ injury and fatality to belted and unbelted drivers shows that the real world distributions of risk with DeltaV are asymptotic to 1.0 over similar DeltaV ranges and over a lower speed range than that predicted from intrusion/complete car crush alone. This is consistent with the proposed hypothesis as human biomechanical loading also influences survivability. While the hypothesis is supported by the presently available limited high-speed collision data, further in-depth investigations should be undertaken to confirm the ultimate limits of survivability.     

Motor vehicle-bicycle crashes in Beijing: irregular maneuvers, crash patterns, and injury severity

This research presents a comprehensive analysis of motor vehicle–bicycle crashes using 4 years of reported crash data (2004–2007) in Beijing. The interrelationship of irregular maneuvers, crash patterns and bicyclist injury severity are investigated by controlling for a variety of risk factors related to bicyclist demographics, roadway geometric design, road environment, etc.Results show that different irregular maneuvers are correlated with a number of risk factors at different roadway locations such as the bicyclist age and gender, weather and traffic condition. Furthermore, angle collisions are the leading pattern of motor vehicle–bicycle crashes, and different irregular maneuvers may lead to some specific crash patterns such as head-on or rear-end crashes. Orthokinetic scrape is more likely to result in running over bicyclists, which may lead to more severe injury. Moreover, bicyclist injury severity level could be elevated by specific crash patterns and risk factors including head-on and angle collisions, occurrence of running over bicyclists, night without streetlight, roads without median/division, higher speed limit, heavy vehicle involvement and older bicyclists.This study suggests installation of median, division between roadway and bikeway, and improvement of illumination on road segments. Reduced speed limit is also recommended at roadway locations with high bicycle traffic volume. Furthermore, it may be necessary to develop safety campaigns aimed at male, teenage and older bicyclists.     

Car size and injury risk: a model for injury risk in frontal collisions.

Empirical studies have established that when pairs of similar cars collide, the relative injury risk between pairs of different size is inversely related to their mass ratio. Further empirical studies have shown that in frontal collisions between dissimilar cars, relative injury risk is inversely proportional to mass ratio raised to the power of n. The value of the exponent n increases with impact speed, with n approximately 1 at low speeds and n ranging from 2.81 to 3.74 for fatalities. In this paper a theory is derived which explains relative injury risk in terms of three parameters: length (or size) ratio, mass ratio and the ratio of collision energy absorption between the colliding vehicles. It is proposed that the ratio of collision energy absorption between colliding vehicles is a function of the structural collapse forces imposed at maximum dynamic crush. The theory shows that the fundamental factor in collisions between pairs of similar cars is size, i.e. length. For collisions between two dissimilar cars, Monte-Carlo simulations using generalised characterisations for the car population yield theoretical predictions that match empirical findings ranging from minor injuries (AISI +) to fatal (AIS6) injuries.     

Influence of pre-collision occupant parameters on injury outcome in a frontal collision

Optimal performance of adaptive restraint systems in the vehicle requires an accurate assessment of occupant characteristics including physical properties and pre-collision response of the occupant. To provide a feasible framework for incorporating occupant characteristics into adaptive restraint schemes, this study evaluates the sensitivity of injury risk in frontal collisions to four occupant parameters: mass, stature, posture and bracing level. The numerical approach includes using commercial multi-body software to develop occupant models that span a range of occupant parameters representative of the real-world driver population. Coupled with a multi-body model of the vehicle interior and standard restraint system, risk of occupant injuries within specific body regions are predicted through numerical simulations in conjunction with established injury risk functions. The results show occupant posture to be the most significant parameter affecting the overall risk of injury in frontal collisions. The causal relationship as predicted using the numerical model has been compared to the traffic injury epidemiology findings, and the feasibility of an analytical methodology to provide real-time estimates of injury severity has been discussed. Preliminary estimates from the study indicate that the proposed methodology will provide a framework to optimize restraint performance and potentially reduce the risk of injuries up to 35% (based on parameter-specific optimization), using accurate information regarding the pre-collision occupant characteristics.     

Automobile intersection collisions—An analytical and experimental investigation of the crash phase

In this study an investigation is made into the crash phase of automobile intersection collisions in which the predominant force is due to the impact; and the external forces on the vehicle, such as tire friction, may be neglected. Analytical as well as experimental methods were used to show that the automobile crash phenomena may be explained macroscopically by rigid body impact theory. Analysis of experimental results indicated the numerical range of the coefficient of friction between the colliding vehicles and the coefficient of restitution necessary to explain the crushing characteristics of the automobile structures and the final socities at the end of the crash phase for different modes of intersection collisions.     

Injuries to belted older children in motor vehicle crashes

Context

The American Academy of Pediatrics and the National Highway Traffic Safety Administration currently recommend that, unless they are under 57 in. in height, 8–12-year-old children use seat belts and all should ride in the rear seats of vehicles. These recommendations assume that the vehicle seat belt should provide adequate protection for these older children in the event of a crash.

Objectives

To describe characteristics of older children in the rear seat using seat belts in crashes, to estimate their risk and body region distribution of injury, and to identify risk factors for injury.

Methods

A representative sample of 6680 seat belt-restrained occupants, 8–12 years of age, seated in the rear seat during crashes involving insured vehicles in 16 US states between December 1998 and December 2007. A telephone interview was conducted with the driver of each vehicle. The main outcome was the parent-reported injury defined as Abbreviated Injury Scale (AIS) 2 or greater injuries.

Results

The risk of injury for belted 8–12 year olds in the rear seat was 1.3%. Head injury was the most common injury (60%), followed by injuries to the face (9%), upper extremity (9%) and abdomen (9%). One out of five (21%) 8–12 year olds either did not use the shoulder portion of the vehicle seat belt or placed it incorrectly behind their back or under their arm. Bivariate analyses indicated a higher risk of injury for these children (1.8%) as compared to children using both the lap and shoulder portions of the seat belt (1.1%). However, this difference was not statistically significant when other risk factors such as crash severity and characteristics of the driver were considered.

Conclusions

Injuries to the head, face, abdomen and upper extremity are the most common injuries to target for improved protection among 8–12 year olds in seat belts. Driver and crash characteristics are important risk factors for injury. A recent federal motor vehicle safety standard requiring lap and shoulder belts in all rear seat positions has the potential to further decrease the risk of injury to older children using seat belts.     

Differences between single- and multiple-automobile fatal accidents

This communication discusses probable similarities and differences between single-vehicle and multiple-vehicle accidents. The investigation is based upon all fatal automobile accidents in the whole of Sweden [1975]. It is shown that single-vehicle accidents are more common on weekends and late in the day. Collisions between vehicles occurred often during bad weather conditions. Single-vehicle accidents happened more often on roads with lower speed limits than did collisions between vehicles. In single-vehicle accidents the drivers were markedly younger, more often drunken, and showed severe signs of social deviance. These features of the drivers in single-vehicle accidents significantly differed from drivers involved in collisions between vehicles even when results were corrected with regard to the fact that there are always two drivers involved in collisions between vehicles, and thus 50% of the drivers in these accidents supposedly represent what could be called average drivers. The use of seat belts and possession of driver's licenses were much lower in single-vehicle accidents. The question of psychopathic states in drivers involved in single-vehicle accidents is raised.     

Safe system approach to reducing serious injury risk in motorcyclist collisions with fixed hazards

Collisions with fixed objects in the roadway environment account for a substantial proportion of motorcyclist fatalities. Many studies have identified individual roadway environment and/or motorcyclist characteristics that are associated with the severity of the injury outcome, including the presence of roadside barriers, helmet use, alcohol use and speeding. However, no studies have reported the cumulative benefit of such characteristics on motorcycling safety. The safe system approach recognises that the system must work as a whole to reduce the net injury risk to road users to an acceptable level, including the four system cornerstone areas of roadways, speeds, vehicles and people. The aim of the present paper is to consider these cornerstone areas concomitantly, and quantitatively assess the serious injury risk of motorcyclists in fixed object collisions using this holistic approach. A total of 1006 Australian and 15,727 (weighted) United States motorcyclist-fixed object collisions were collected retrospectively, and the serious injury risks associated with roadside barriers, helmet use, alcohol use and speeding were assessed both individually and concomitantly. The results indicate that if safety efforts are made in each of the safe system cornerstone areas, the combined effect is to substantially reduce the serious injury risk of fixed hazards to motorcyclists. The holistic approach is shown to reduce the serious injury risk considerably more than each of the safety efforts considered individually. These results promote the use of a safe system approach to motorcycling safety.     

Motorcycle helmet use and the risk of head,neck, and fatal injury: Revisiting the Hurt Study

Most studies find strong evidence that motorcycle helmets protect against injury, but a small number of controversial studies have reported a positive association between helmet use and neck injury. The most commonly cited paper is that of Goldstein (1986). Goldstein obtained and reanalyzed data from the Hurt Study, a prospective, on-scene investigation of 900 motorcycle collisions in the city of Los Angeles. The Goldstein results have been adopted by the anti-helmet community to justify resistance to compulsory motorcycle helmet use on the grounds that helmets may cause neck injuries due to their mass. In the current study, we replicated Goldstein’s models to understand how he obtained his unexpected results, and we then applied modern statistical methods to estimate the association of motorcycle helmet use with head injury, fatal injury, and neck injury among collision-involved motorcyclists. We found Goldstein’s analysis to be critically flawed due to improper data imputation, modeling of extremely sparse data, and misinterpretation of model coefficients. Our new analysis showed that motorcycle helmets were associated with markedly lower risk of head injury (RR 0.40, 95% CI 0.31–0.52) and fatal injury (RR 0.44, 95% CI 0.26–0.74) and with moderately lower but statistically significant risk of neck injury (RR 0.63, 95% CI 0.40–0.99), after controlling for multiple potential confounders.     

Predicting injury risk with “New Car Assessment Program” crashworthiness ratings

The relationship between crashworthiness ratings produced by the National Highway Traffic Safety Administration's (NHTSA's) New Car Assessment Program (NCAP) and the risk of incapacitating injury or death for drivers who are involved in single-car, fixed-object, frontal collisions was examined. The results are based on 6,405 such crashes from the Motor Vehicle Traffic Accident file of the Texas Department of Highways and Public Transportation. The risk of injury was modeled using logistic regression taking into account the NCAP test results for each individual model of car and the intervening effects of car mass, age of the driver, restraint use, and crash severity. Three measures of anthropometric dummy response, Head Injury Criterion (HIC), Chest Deceleration (CD), and femur load were used to indicate vehicle crash test performance. The results show that there is a significant relationship between the results of the NCAP tests and the risk of serious injury or death in actual single-car frontal accidents. In terms of overall injury, chest deceleration was a better predictor than the Head Injury Criterion. For restrained drivers, crash severity, driver age, and chest deceleration were significant parameters for predicting risk of serious injury or death; the risk of injury decreased as chest deceleration decreased. The results were similar for unrestrained drivers although vehicle mass and femur load were also significant factors in the model. The risk of overall injury decreased as chest deceleration decreased but appeared to decrease as femur load increased.     

Injury severity of pedestrians,bicyclists and motorcyclists resulting from crashes with reversing cars

ObjectivePedestrians, bicyclists and motorcyclists can suffer serious injury in road traffic crashes. To date, no studies examine the injury severity within this vulnerable cohort following collisions with reversing cars.Material and methodsOur institution prospectively maintains a database including medical and technical information regarding traffic accidents in our area, including urban and suburban regions. In a retrospective review of this database, the authors describe the injury severity of pedestrians, bicyclists and motorcyclists following traffic crashes involving reversing cars. Injury severity was described using the abbreviated injury scale (AIS) as well as the maximum abbreviated injury scale (MAIS).ResultsThis study included 234 crashes occurring between 1999 and 2012. The lower extremity was injured most often while also suffering more severe injuries with a median AIS of 1 compared to 0 in all other documented body regions. The upper extremity was injured second most often. AIS ranging from 4 to 6 were infrequent. AIS 3 however, was documented for the legs in 4.3% of patients. MAIS 0, 1, 2, 3, 5 and 9 were found in 1, 164, 46, 14, 1, and 8 patients in the study cohort, respectively. Pedestrians and motorcyclists were seriously injured in 9.1% and 9.6% of cases, respectively. In contrast, no bicyclists suffered serious injuries. As to the zone of impact, most collisions occurred at the rear center of the vehicle (35%) followed by rear left (26%), rear right (20%), side rear (11%), side center (4%) and side front (3%). 204 (87.2%) collisions occurred during the day, 19 (8.1%) at night and 11 (4.7%) at twilight. Speed was similar in crashes involving pedestrians, bicyclists and motorcyclists, being as high as 7.0 ± 3.6, 7.0 ± 4.0 and 7.9 ± 4.2 km/h respectively.ConclusionsThis is the first study that analyzes injury severity among these vulnerable road users following collisions with reversing vehicles. The majority of collisions occur at low impact speed during the day. Most injuries resulting from these collisions are not serious, however pedestrians are at greatest risk of severe injury to any body region. The lower extremities suffer the most serious and frequent injuries within this cohort.     

Influence of anthropometry on the kinematics of the cervical spine and the risk of injury in sled tests in female volunteers

The objective of this study was to investigate the influence of anthropometric data on the kinematics of the cervical spine and the risk factors for sustaining a neck injury during rear-end collisions occurring in a sled test. A rear-end collision with a velocity change (DeltaV) of 6.3 km/h was simulated in a sled test with eight healthy female subjects. The study analysed the association of anthropometric data with the initial distance between the head and the head restraint, defined kinematic characteristics, the neck injury criterion (NIC) and the neck injury criterion minor (NICmin). The head circumference is negatively associated (r=-0.598) with the initial distance between the head and the head restraint, the maximal head extension (r=-0.687) and the maximal dorsal angular head acceleration (r=-0.633). The body weight (r=0.800), body height (r=0.949) and thorax circumference (r=0.632) are positively associated with the maximal ventral head translation. The neck length correlates positively with the NIC (r=0.826) and negatively with the NICmin (r=-0.797). Anthropometric factors influence the kinematics of the cervical spine and the risk of injury. A high risk of injury may be assumed for individuals with a small head circumference, long neck, tall body height and high body weight.     

Identifying significant predictors of injury severity in traffic accidents using a series of artificial neural networks

Understanding the circumstances under which drivers and passengers are more likely to be killed or more severely injured in an automobile accident can help improve the overall driving safety situation. Factors that affect the risk of increased injury of occupants in the event of an automotive accident include demographic or behavioral characteristics of the person, environmental factors and roadway conditions at the time of the accident occurrence, technical characteristics of the vehicle itself, among others. This study uses a series of artificial neural networks to model the potentially non-linear relationships between the injury severity levels and crash-related factors. It then conducts sensitivity analysis on the trained neural network models to identify the prioritized importance of crash-related factors as they apply to different injury severity levels. In the process, the problem of five-class prediction is decomposed into a set of binary prediction models (using a nationally representative sample of 30358 police-recorded crash reports) in order to obtain the granularity of information needed to identify the "true" cause and effect relationships between the crash-related factors and different levels of injury severity. The results, mostly validated by the findings of previous studies, provide insight into the changing importance of crash factors with the changing injury severity levels.