Road mobility and the risk of road traffic accident as a driver. The impact of medical conditions and life events

STUDY OBJECTIVE: We conducted a longitudinal investigation of the impact of self-reported life events and medical conditions on changes in road mobility on the wheel between 2000 and 2002 in order to assess whether these changes would affect the risk of road traffic accident (RTA). METHODS: Data are from a cohort of workers and retirees from the French national gas and electricity companies (the Gazel cohort). In the present study, 10,483 participants were included (7843 men aged 51-61 years and 2640 women aged 46-61 years, in 2000). The link between mobility and the risk of RTA was approximated using data on RTA number during lifetime and reported mobility in 2000. We then compared changes in road mobility between 2000 and 2002 resulting from life events and medical conditions reported to have occurred in the year 2001 or changed when compared to year 2000. We also compared road mobilities in 2000 in order to assess any pre-existing differences before life events and medical conditions. This led to estimation of the effect of road mobility changes on the risk of RTA. RESULTS: Changes in road mobility associated with life events and medical conditions were only found among men. These changes in road mobility were minimal. Ensuing changes in the risk of RTA were estimated to be small (odds-ratios ranged from 0.94 to 1.01). The only life events found to be associated with increased road mobility was an important purchase. Hospitalization, serious RTA, and retiring were associated with reduced road mobility. Concerning medical conditions, men who reported cataract, angina pectoris, diabetes, anxiety and stress, sleep disorder, and depression decreased their road mobility. CONCLUSION: We found no or moderate changes in road mobility resulting from life events and medical conditions, suggesting that results from previous published studies that assessed the impact of life events or medical conditions on RTA were not jeopardized by improper adjustment for road mobility.     

Crash risk of older drivers after attending a mature driver education program

PURPOSE: The primary aim of this study was to determine if the crash rate of aging drivers can be mitigated by post-license driver education. DESIGN AND METHODS: This study of 884 older drivers who attended the 55 Alive/Mature Driving program was conducted in three phases. Phase 1, which examined self-selection bias of seniors attending the driver education program, and Phase 2, which examined changes in crash rate after attending the program, were carried out through analysis of driving records before and after attending the course. In Phase 3, the use of selection, optimization, and compensation strategies by older male drivers who attended 55 Alive/Mature Driving was addressed through focus group interviews. RESULTS: Findings showed a self-selection bias among older drivers who attended 55 Alive/Mature Driving. Results also showed attendance at the program was associated with an increased number of crashes for men aged 75 years and older, but no effect on subsequent crashes of younger men and women of all ages. Focus group sessions suggested older men who attended the program used fewer strategies to cope with their declining skills. IMPLICATIONS: Recognizing and understanding characteristics and behaviors of older drivers who attend remedial driver education is essential to the design and delivery of successful driver safety programs.     

How to identify the key factors that affect driver perception of accident risk. A comparison between Italian and Spanish driver behavior

Road crashes can be caused by different factors, including infrastructure, vehicles, and human variables. Many research studies have focused solely on identifying the key factors that cause road crashes. From these studies, it emerged that human factors have the most relevant impact on accident severity. More specifically, accident severity depends on several factors related directly to the driver, i.e., driving experience, driver's socio-economic characteristics, and driving behavior and attitudes. In this paper, we investigate driver behaviors and attitudes while driving and specifically focus on different methods for identifying the factors that most affect the driver's perception of accident risk. To this end, we designed and conducted a survey in two different European contexts: the city of Cosenza, which is located in the south of Italy, and the city of Granada, which is located in the south of Spain. Samples of drivers were contacted for their opinions on certain aspects of driving rules and attitudes while driving, and different types of questions were addressed to the drivers to assess their judgments of these aspects. Consequently, different methods of data analysis were applied to determine the aspects that heavily influence driver perception of accident risk. An experiment based on the stated preferences (SP) was carried out with the drivers, and the SP data were analyzed using an ordered probit (OP) model. Interesting findings emerged from different analyses of the data and from the comparisons among the data collected in the two different territorial contexts. We found that both Italian and Spanish drivers consider driving in an altered psychophysical state and violating the overtaking rules to be the most risky behaviors.     

An assessment of the effect of driver age on traffic accident involvement using log-linear models

Statistical models were developed to help understand the relationship between the driver age and several important accident-related factors and circumstances such as injury severity, collision types, average daily traffic (ADT), roadway character, speed ratio, alcohol involvement, and accident location. By using techniques of categorical analysis on the 1994 and 1995 Florida accident database, four log-linear models with three variables in each model with all possible two-way interactions were developed. In order to compare the differences in response between the age groups and a particular accident-related variable, odds multipliers were computed. The effects of age and accident-related factors were examined, and interactions among them were considered. The results indicated significant relationships between the driver age and ADT, injury severity, manner of collision, speed, alcohol involvement, and roadway character. The findings' contribution to the understanding of the effect of age on accident involvement is addressed. A discussion of how log-linear and logit modeling with estimation of `odds multipliers' may contribute to traffic safety studies is also provided.     

Effective dialogues in driver education

The Norwegian driver education programme is extensive, systematic and comprehensive. The syllabus intentions have high expectations for pupil learning, and in the learning situation the ability of teachers to utilise dialogue as an effective learning tool is put to the test. Over a 5-year period we have studied learning situations in all areas of the Norwegian driver education programme. In this article we present findings based on observations of teacher-pupil interaction during on-road practice and discuss how teachers may form the dialogue into an effective learning tool in order to tap the learning potential that is embedded in driver education programmes. The education of responsible drivers requires that teacher-pupil dialogues bring about a shared understanding of a full traffic context during on-road practice. It becomes evident that different teacher supportive approaches pave the way to ‘intersubjectivity’ of occurring traffic contexts in qualitatively different ways. Teachers use both ‘clarifying’ and ‘elaborative’ processes to prepare the learner for responsible driving. The establishment of a mutual understanding is a continuous dialogical process in which concepts become mediating tools. How the two conceptual worlds of teacher and learner merge makes a basic level for subsequent scaffolding processes during on-road practice.     

Estimating the accident potential of an Ontario driver

To run a "demerit point" program, one uses routinely available information about drivers to identify those who are most likely to have an accident in the near future. On the basis of a four-year record for a large sample of Ontario drivers, we have examined several tools for the identification of such drivers and investigated how they perform. Each driver is thought to have an expected number of accidents, m. In a group of drivers with common traits (such as age, gender, record of convictions and accidents) the ms have a mean E(m) and a variance VAR(m). Estimates of E(m) and VAR(m) for all combinations of traits can be obtained within the framework of a multivariate statistical model. The same estimates can then be used to judge how well a model identifies drivers who have a large m. In such a multivariate model it is important to use data about previous accidents and convictions. However, the accuracy with which the m of a driver can be estimated is not improved much by distinguishing between offence type or between accidents as being "at fault" or "not at fault". Without much loss in estimation accuracy, one may attach a weight 1 to a conviction and 2 to an accident. Model performance is described in tangible terms: how many accidents are recorded by the drivers identified by a model, what proportion of identified drivers are "false positives," how many drivers with high m remain unidentified. We conclude that by using a multivariate statistical model one can do substantially better than by using a demerit point scheme in which points are assigned to offenses on the basis of their perceived seriousness. However, even when the best model is used to identify a large group of drivers, many will be false positives.     

The effects of vehicle model and driver behavior on risk

We study the dependence of risk on vehicle type and especially on vehicle model. Here, risk is measured by the number of driver fatalities per year per million vehicles registered. We analyze both the risk to the drivers of each vehicle model and the risk the vehicle model imposes on drivers of other vehicles with which it crashes. The "combined risk" associated with each vehicle model is simply the sum of the risk-to-drivers in all kinds of crashes and the risk-to-drivers-of-other-vehicles in two-vehicle crashes. We find that most car models are as safe to their drivers as most sport utility vehicles (SUVs); the increased risk of a rollover in a SUV roughly balances the higher risk for cars that collide with SUVs and pickup trucks. We find that SUVs and to a greater extent pickup trucks, impose much greater risks than cars on drivers of other vehicles; and these risks increase with increasing pickup size. The higher aggressivity of SUVs and pickups makes their combined risk higher than that of almost all cars. Effects of light truck design on their risk are revealed by the analysis of specific models: new unibody (or "crossover") SUVs appear, in preliminary analysis, to have much lower risks than the most popular truck-based SUVs. Much has been made in the past about the high risk of low-mass cars in certain kinds of collisions. We find there are other plausible explanations for this pattern of risk, which suggests that mass may not be fundamental to safety. While not conclusive, this is potentially important because improvement in fuel economy is a major goal for designers of new vehicles. We find that accounting for the most risky drivers, young males and the elderly, does not change our general results. Similarly, we find with California data that the high risk of rural driving and the high level of rural driving by pickups does not increase the risk-to-drivers of pickups relative to that for cars. However, other more subtle differences in drivers and the driving environment by vehicle type may affect our results.     

Perceived risk as a determinant of driver behavior

Decision skill appears to be the most error-prone component of the driving task. It may therefore be the prime source of road accidents. Decisions which drivers make about vehicle maneuvres appear to be largely a function of the risk they perceive in the situation. Three studies were therefore carried out to investigate drivers' risk-taking behavior.     

The impact of driver education on self-reported collisions among young drivers with a graduated license

In this study, we assess the impact of driver education on the risk of collisions in a Graduated Licensing System (GLS). Ontario's GLS requires all new drivers to successfully pass through two stages of graduated license (referred to as G1 and G2, respectively) before full licensure is granted. Surveys of driving behaviour and related factors were administered to Grades 11 and 12 students with a graduated license in seven Ontario schools in 1996 and 1998. A total of 1533 students completed the survey in 2 years. Multivariate logistic regression analysis revealed a significantly lower odds of self-reported collision involvement among G1 license holders with driver education (OR: 0.31, 95% CI: 0.12-0.83). No significant effects were observed for G2 license holders. Other significant predictors of collisions include sex of driver, months of licensure and kilometers driven for G2 license holders. These results suggest that the impact of driver education may be dependent on the stage of driver learning in which it occurs.     

Speed as a measure of driver risk: Observed speeds versus driver and vehicle characteristics

This investigation was performed to determine relationships between driver and vehicle characteristics and freely chosen speeds of cars on a two lane road with little commercial or residential development. Speed is taken as a measure of a driver's willingness to expose himself to risk of accident, in the same way that short freeway headways were interpreted in an earlier study. A total of 6638 passenger car speeds were measured by radar while each oncoming vehicle was simultaneously photographed. Driver and vehicle characteristics were derived from the photographs, both by direct observation (vehicle type, driver sex, presence of front seat passengers, seat belt use) and from the car license plate through the use of State vehicle registration and driver licensing files. The State files provided the car mass and model year and the owner (usually driver) age, sex, and recorded accidents and violations. Higher speeds were observed for younger drivers, drivers with prior accidents and convictions, newer cars, heavier cars and cars with no passengers.     

The effects of range versus nonrange driver training on the accident and conviction frequencies of young drivers

The sample consisted of 2,057 high school students from five California high schools who were assigned randomly either to a traditional driver training program (N = 918) or to an experimental program utilizing a driving range (N = 1,139). Aspects of their performance during driver training were measured, as well as performance on tests required for driver licensing and number of days between training and licensing. In addition, Department of Motor Vehicles files supplied information on their accident and conviction records within the year following the beginning of driver training. Results showed that nonrange students performed significantly better on the following training variables: knowledge posttest (p < 0.01), simulator score (p < 0.01), and driver course grade (p < 0.05). There were no significant differences between range and nonrange students on driver licensing test scores or in the amount of time spent in becoming licensed. However, range students had fewer total accidents than nonrange students (p < 0.05) in the year following the beginning of training. Time spent on the range during training was not related to frequency of accidents or convictions for range students. Cost-benefit aspects of range training were discussed. Range training is operationally less expensive than traditional training, but costs of constructing a driving range may vary appreciably.     

Perception, attitudes and beliefs, and openness to change: implications for older driver education

With a rapidly aging population, strategies for improving driver safety are beginning to emerge that focus on changing driving behaviors and knowledge. We examined the perceptions of risk, beliefs and attitudes, and openness to change of 86 older participants voluntarily attending a driver education program. It appeared that most people attending these sessions were not necessarily concerned about their own driving, safety or abilities, but were interested in maintaining mobility. They were conservative and reasonably consistent in their attitudes toward traffic regulations and safe driving practices. Some gender differences emerged with more men than women being resistant to changing their driving habits, more men than women reporting that they drive after consuming alcohol and more women than men identifying a role for their families in decision-making regarding driving cessation. This suggests that educational material may need to be targeted differently for men and women. It is anticipated that psychosocial factors related to driving such as driver perception, beliefs and openness to change will be useful for maximizing the fit between education program content and outcomes.     

The role of motorcyclist and other driver behaviour in two types of serious accident in the UK

Motorcycle accidents have somewhat different characteristics from accidents involving other classes of road user. They include in particular 'right of way' accidents, and accidents involving loss of control on curves or bends. A sample of 1790 accident cases was considered, including 1003 in detail, from UK midland police forces, involving motorcyclists of all ages, and covering the years 1997-2002 inclusive. Significant differences were discovered in the sample with respect to types of accidents involving motorcyclists (and their blameworthiness). There seems to be a particular problem surrounding other road users' perception of motorcycles, particularly at junctions. Such accidents often seem to involve older drivers with relatively high levels of driving experience who nonetheless seem to have problems detecting approaching motorcycles. Motorcyclists themselves seem to have far more problems with other types of accident, such as those on bends or curves. The implications of these findings are discussed.     

The optimism bias and traffic accident risk perception

Research suggests that people are excessively and unrealistically optimistic when judging their driving competency and accident risk. In this study, college-age drivers compared their risk of being involved in a variety of described traffic accidents relative to their peers. They also rated each of the accidents along a number of dimensions hypothesized as being related to optimism. In addition, subjects provided global estimates of their driving safety, skill, and accident likelihood. Significant optimism was evident for both the accidents and the global ratings. Optimism increased with driving experience and marginally with age. Those with more driving experience considered human factors to be more important in accident causation; those assigning more importance to human factors also rated themselves as more skillful drivers. For the specific accidents, perceived controllability was a strong predictor of optimism. The findings for controllability are interpreted in terms of other recent data and hypothesized explanations of the optimism bias. In general, it appears that optimism arises because people persistently overestimate the degree of control that they have over events.     

The effect of roundabout design features on cyclist accident rate

Roundabouts are known to result in fewer traffic accidents than traditional intersections. However, this is to a lesser degree true for bicycles than for vehicles. In this paper, we aimed at establishing statistical relationships through Poisson regression and logistic regression analyses between yearly rate of cyclist accidents on one hand and roundabout geometry, age and traffic volume (vehicles and cyclists) on the other. We related all roundabout cyclist accidents recorded by the hospital emergency department of the town of Odense, Denmark, through the years 1999-2003 (N=171) to various geometric features, age and traffic volume of all roundabouts on the Danish island of Funen (N=88). Cyclist and vehicle volumes turned out to be significant predictors in most of our models-the higher the volumes, the more accidents. Moreover, potential vehicle speed was a significant predictor, and so was age of the roundabout-older roundabouts related to more accidents and higher accident probability. Excluding 48 single cyclist accidents strengthened the relationship between accidents on one hand and vehicle and cyclist volume and potential vehicle speed on the other. This stresses the significance of speed and traffic volume for traffic accidents with more than one partner involved. The 48 single cyclist accidents were significantly related to the traffic volume of cyclists only. Due to our limited number of observations, the models should be regarded as indicative.     

Technical diagnostics in accident risk assessment

For a comprehensive assessment of safety of hazardous facilities, an accident risk ratio is used. Existing methodologies of risk assessment do not account for technical conditions of the facility and the degree of its defectiveness. This work demonstrates the possibility and necessity of a broader use of nondestructive testing (NDT) and technical diagnostics (TD) to estimate the probability of an accident, formulates the requirements for analyzing the risk, and establishes the line of development for these approaches. We consider the issues related to introducing new requirements for NDT and TD, which deal with representing the quantitative values of NDT, i.e., reliable data on the size of defects and measurement errors. We prove the necessity of using the methods of probabilistic fracture mechanics for assessing the real values of accident probability.     

An examination of gender differences in traffic accident risk perception.

Excessively optimistic judgements of driving competency and accident risk have often been implicated in the disproportionate involvement of young males in traffic crashes. In this study, young male and female drivers (ages 18-24) were asked to judge their relative driving safety, skill, and accident likelihood. Comparisons were made using both peers and the average motorist as referent groups. Subjects then rated 15 risky driving behaviors on four dimensions: frequency in everyday driving, seriousness, accident potential, and apprehension likelihood. Self-report driving experience/history data were also collected. Substantial optimism was evident in both sexes, but males tended to be more optimistic, particularly when judging their driving skill. Males were equally optimistic with respect to the two referent groups; females tended to be less optimistic when making comparisons to the average motorist. Males and females held similar perceptions concerning the frequency and accident likelihood of the risky behaviors, but males perceived the behaviors as generally less serious and less likely to results in accidents. Regression analyses showed that considerably more variance in optimism could be explained for males than females. Driving record was the single best predictor of perceived safety; its role, however, was diminished for perceived skill and subjectively estimated accident likelihood.