The variation of drivers' accident rates between drivers and over time.

Accident records of individual drivers in eight large samples from the general driving population have been analysed as nonhomogeneous Poisson processes, i.e. by assuming that each driver's accidents occur randomly with an individual underlying accident rate that varies in time. Previous hypotheses about the form of this variation are reviewed. The moments of the distribution over drivers of individual underlying accident rates averaged over periods of one or more years are estimated; they indicate that most of the distributions are intermediate in form between the gamma and lognormal distributions. The results suggest the presence of an overall annual factor that multiplies all the individual rates; when this is removed the remaining process is approximately stationary (i.e. the mean and standard deviation are approximately constant in time). The coefficient of variation of individual accident rates falls slowly as the length of the period over which they are averaged increases, indicating positive correlation between the underlying accident rates of the same drivers in different periods. These correlations are estimated directly from the accident frequency data, which appears to be a new and useful method of analysis. For one sample, which spans 14 years, the correlation between two adjacent years is about 0.74 and falls approximately linearly to about 0.49 for two years separated by a gap of 12 years. A "switching process" with differing individual means, previously proposed for drivers' accidents by Bartlett, does not appear to fit these results well. A "scaling process," studied by Mandelbrot and previously found to apply in a number of different fields, provides a better fit to the data and could represent the combined effect of a hierarchy of switching processes operating on different time scales, in accordance with what is known or conjectured about the variation of factors affecting accident rates. Although the data analysed are affected by variation in exposure between drivers, the methods and ideas used have implications that may help to resolve the long-standing dispute about individual accident proneness.     

Bus driver accident record: the return of accident proneness

One of the assumptions of the theory of accident proneness is that drivers’ accident liability is stable over time, which was tested in the present paper. Previous investigations of this problem (or rather the conclusions) were found to be deficient because they did not take into account the statistical problem of low variance in the accident variable. However, by correlating the between time periods association coefficient and the mean number of accidents across several samples, this problem can be overcome. Therefore, the stability of accident record over time was investigated in five samples of British bus drivers. It was found that the size of the correlations between time periods increased with the increase in mean accident frequency. Furthermore, this increase could be described by a linear regression line, which fit the various points extremely well. Also, the size of correlations of ‘at fault’ accidents increased faster with the mean than did ‘all accidents’, although the latter had a higher initial value. It was therefore concluded, in contrast to previous authors, that the accident record of drivers is quite stable over time and that the very low correlations that have often been found were due to the samples and methods used (low-risk drivers and short time periods equalling low crash means) and not of any inherent instability in drivers’ behaviour and/or accident record. It was also concluded that only culpable accidents should be used for this type of calculation. No evidence was found for a decrease in correlation size between single years' accidents when time periods between the years were lengthened, i.e. accidents in one year predicted accidents in several other years equally well. However, the period used was rather short. The results are discussed with reference to training intervention for accident-involved drivers, especially for organisations with major fleets, such as bus companies.     

Accident proneness,does it exist? A review and meta-analysis

Accident related health problems have been suggested to cluster within persons. This phenomenon became known as accident proneness and has been a subject of many discussions. This study provides an overview of accident proneness. Therefore, 79 articles with empirical data on accident rates were identified from databases Embase, Medline, and Psychinfo. First, definitions of accidents varied highly, but most studies focused on accidents resulting in injuries requiring medical attention. Second, operationalisations of accident proneness varied highly. Studies categorised individuals into groups with ascending accident rates or made non-accident, accident, and repetitive accident groups. Third, studies examined accidents in specific contexts (traffic, work, and sports) or populations (children, students, and patients). Therefore, we concluded that no overall prevalence rate of accident proneness could be given due to the large variety in operationalisations. However, a meta-analysis of the distribution of accidents in the general population showed that the observed number of individuals with repeated accidents was higher than the number expected by chance. In conclusion, accident proneness exists, but its study is severely hampered by the variation in operationalisations of the concept. In an effort to reach professional consensus on the concept, we end this paper with recommendations for further research.     

Road accidents and rainfall in a large Australian city

We investigate the impact of rainfall on daily road accidents in the metropolitan area of Melbourne, Australia, over 1987-2002. Our analysis from several viewpoints of the accident count, which has been normalised for variation in traffic volume, indicated that the effect of rainfall is multifaceted. Owing to a large non-linear trend a subdivision into three epochs (1987-1991, 1992-1996 and 1997-2002) was made. Nominal daytime and nighttime as well as 3h raw counts were available for the first two epochs only. Generally, the effect of rainfall across the epochs shows a tendency for larger values in autumn with smaller values in spring. For the daily, daytime and nighttime cases there is an approximate 40% decrease in both the volume-normalised dry and wet means from the first to second epoch. Since the second epoch is wetter than the first, and both dry and wet cases are affected in a similar way, then it appears that a non-weather influence is at work. It is suggested that law enforcement measures may be largely responsible. We obtained a conservative estimate of relative risk of an accident in wet conditions based on a matched-pair analysis of 3h dry and wet periods over the first two epochs (1987-1996). As with other studies we find that the risk is greater than unity in almost all cases suggesting that the presence of rainfall consistently represents a driving hazard. Rainfall occurring after a dry spell has an enhanced effect on the volume-normalised accident count as the spell duration increases. The effect of dry spells is more clearly described when broken down by rain class. Generally, there is an increase in the impact of a dry spell when it first rains as the spell duration and rainfall amount increase.     

Self-reported motorcycle riding behaviour among school children in India

Studies on traffic accidents among underage users of motorcycles are seldom seen in literature. This study was done in Yamunanagar, India where boys as young as 8 years ride motorcycles. It attempts to find out the behavioural and non-behavioural factors leading to motorcycle use and the predisposition to accidents among male school children aged between 10 and 16 years. A questionnaire was used to evaluate those factors among 1760 subjects in 38 schools. Fifteen percent of subjects had had an accident while riding motorcycle. Most of the behavioural and all the non-behavioural factors have a statistically significant influence on accident proneness. Aggressive behaviour and previous encounter with the police are the two strong predictors of accidents (p<0.001). Children as riders are exposed to higher risks of accident and longer life with disability. It also explains how these children behaviourally take up adult roles and seek adult risk taking attitudes. The implications of child motorcycle riders upon children themselves and on the society are discussed for a greater discourse on road safety motorcycle riding policy and to highlight the behavioural and non-behavioural factors that are associated with traffic accidents.     

Genetic Study Identifies CBLN4 as a Novel Susceptibility Gene for Accident Proneness

Frequent traffic accidents constitute a major danger to human beings. The accident-prone driver who has the stable physiological, psychological, and behavioral characteristics is one of the most prominent causes of traffic accidents. The internal link between the individual characteristics and the accident proneness has been a difficult point in the accident prevention research. The authors selected accident-prone drivers as cases and safe drivers as controls (case-control group) from 18,360 drivers who were enrolled from three public transportation incorporations of China using area stratified sampling method. The case-control groups were 1:1 matched. The authors performed genome-wide association study (GWAS) by 179 cases and 179 controls using the U.S. Affymetrix Genome-Wide Human Mapping SNP 6.0 Array. The authors observed that the gene frequencies of 34 single-nucleotide polymorphisms (SNPs) in three regions of cases were higher than those in the control (P<10⁻⁴). The authors then tested two independent replication sets for strong association 6 SNPs in 349 pairs of case-control drivers using the U.S. ABI 3730 sequencing method. The results indicated that SNP rs6069499 within linked CBLN4 gene are strongly associated with accident proneness (P_combined=6.37×10⁻¹⁰). According to CBLN4 gene mainly involved in adrenal development and the regulation of secretion, the authors performed 12 biochemical parameters of the blood using radioimmunoassay. The levels of dopamine (DA) and adrenocorticotropic (ACTH) hormone showed significant differences between accident-prone drivers and safe drivers (P_DA=0.03, P_ACTH=0.01). It is suggested that the accident-prone drivers may have the idiosyncrasy of susceptibility.     

Drifting into failure: theorising the dynamics of disaster incubation

Ergonomic theory holds that accidents are preceded by periods of gradually increasing (but essentially unrecognised) risk, known originally in man-made disaster theory as the incubation period. This paper discusses the theorising of the dynamics of such accident incubation. It considers theoretical contributions – ranging from high-reliability to control theory to resilience engineering – for their ability to illuminate the driving forces behind a gradual shift in norms and erosion of safety margins, and for their ability to effectively track and represent such changes over time.     

The special severity of occupational accidents in the afternoon: "the lunch effect"

The severity of occupational accidents suffered by construction workers at different hours of the day is analyzed in this study. It may be seen that the interval of time between 13:00 and 17:00 has incomprehensibly high rates of severe and fatal accidents in comparison with any other. We associate this higher accident rate with what we have termed the “lunch effect”. We studied 10,239,303 labor accidents in Spain over the period 1990–2002. The relationships between potential risk factors for occupational accidents around lunch in Spain, especially alcohol consumption are studied, using two methods: analysis of national archival data of 2,155,954 occupational accidents suffered by workers in the construction sector over the period 1990–2002 and a survey study. This study also seeks to contribute the opinions of the workers themselves regarding the causes that might explain this situation.     

An analysis of nighttime pedestrian accidents at specially illuminated crosswalks

The purpose of this research was to examine the effect of the special crosswalk illumination and signing system presently warranted for use in Israel. The study was of the before and after type and treated the fixture as an entirety, without attempting to distinguish between differential effects of the sign and of the illumination provided on the crosswalk. Ninety nine installations were studied where no other engineering changes had been made in the “after” period. It was found that a significant reduction in pedestrian night accidents was achieved where the installations were made, while the reduction in day accidents was not statistically significant. In addition to the analysis of night and day accident changes at sites where the system was installed, comparison was made between a number of these sites and a group of unlit “control crosswalks”, each of which either adjoined the lit crosswalk at the same intersection or was nearby on the same street. Accidents at these control crosswalks did not show a significant change over the period studied. Additional factors which were investigated, such as pedestrian and vehicle flow, weather and national trend of pedestrian accidents, all supported the conclusion that it was the installation of the sign and lighting system which brought about the observed reduction in accidents. It was further found that the system represents a highly worthwhile investment in terms of costs and accident reduction benefits.     

A risk analysis of winter navigation in Finnish sea areas

Winter navigation is a complex but common operation in north-European sea areas. In Finnish waters, the smooth flow of maritime traffic and safety of vessel navigation during the winter period are managed through the Finnish–Swedish winter navigation system (FSWNS). This article focuses on accident risks in winter navigation operations, beginning with a brief outline of the FSWNS. The study analyses a hazard identification model of winter navigation and reviews accident data extracted from four winter periods. These are adopted as a basis for visualizing the risks in winter navigation operations. The results reveal that experts consider ship independent navigation in ice conditions the most complex navigational operation, which is confirmed by accident data analysis showing that the operation constitutes the type of navigation with the highest number of accidents reported. The severity of the accidents during winter navigation is mainly categorized as less serious. Collision is the most typical accident in ice navigation and general cargo the type of vessel most frequently involved in these accidents. Consolidated ice, ice ridges and ice thickness between 15 and 40 cm represent the most common ice conditions in which accidents occur. Thus, the analysis presented in this article establishes the key elements for identifying the operation types which would benefit most from further safety engineering and safety or risk management development.     

驾驶员与儿童事故倾性研究

文章通过对全国部分城市驾驶员交通事故和儿童意外伤害事故的流行病学研究结果发现：（１）驾驶员交通事故和儿童意外伤害事故检出率不存在地区性差异；（２）驾驶员交通事故和儿童意外伤害事故的检出率无显著性的年龄差异；（３）不同年龄段驾驶员和儿童，男性事故检出率均高于女性事故检出率；（４）极少数的事故人群具有事故倾向性：在驾驶人群中有６％～８％的事故倾性驾驶员，其引起的交通事故数占总事故数的３０％～４０％，在１～１４岁儿童中有１％～２％的事故倾性儿童，其发生的意外伤害数占意外伤害总数的２５％～３５％；（５）事故倾性驾驶员和事故倾性儿童再发事故的比率均比对照组高。文章从流行病学角度证实了事故倾性人群的存在，并对事故倾性的本质作了初步探讨。     

驾驶员与儿童事故倾性研究

文章通过对全国部分城市驾驶员交通事故和儿童意外伤害事故的流行病学研究结果发现 :(1 )驾驶员交通事故和儿童意外伤害事故检出率不存在地区性差异 ;(2 )驾驶员交通事故和儿童意外伤害事故的检出率无显著性的年龄差异 ;(3 )不同年龄段驾驶员和儿童 ,男性事故检出率均高于女性事故检出率 ;(4 )极少数的事故人群具有事故倾向性 :在驾驶人群中有 6%～ 8%的事故倾性驾驶员 ,其引起的交通事故数占总事故数的 3 0 %～ 40 % ,在 1～ 1 4岁儿童中有 1 %～ 2 %的事故倾性儿童 ,其发生的意外伤害数占意外伤害总数的2 5 %～ 3 5 % ;(5 )事故倾性驾驶员和事故倾性儿童再发事故的比率均比对照组高。文章从流行病学角度证实了事故倾性人群的存在 ,并对事故倾性的本质作了初步探讨。     

Effects of traffic signal installation on accidents

A before-and-after accident study of 31 recently signalized intersections within the City of Milwaukee was performed, using three years of accident data before along with at least two and usually 3 yr of data after signalization. City-wide volume and accident trends were used as a control to adjust the data.Upon signalization, little or no change was noted overall either in the number of accidents, or in severity as measured by property-damage-only-equivalent (PDOE) and/or severity index (SI). A significant decrease of 34% in the number of “right-angle” accidents was accompanied by a significant increase of 37% in “rear-end” accidents (including side-swipes), and a significant increase of 41% in “other” (head-on, vehicle/bicycle, fixed-object, etc.) accidents. “Vehicle/pedestrian” and “opposing direction—one turning left” type accidents did not change significantly.Various parameters involving geometrics, traffic control and vehicular volumes were analyzed. These parameters appeared to have little effect on the change in both number and severity of accidents upon signalization of the intersections in this study.A significant shift in accident severity was noted, however, between periods of flash and normal operation. Without significant changes in the number of accidents, the PDOE accidents increased 42% during flash, with a corresponding decrease of 8% during normal operation.     

An evaluation of the national safety council''s defensive driving course in various states

The National Safety Council's Defensive Driving Course (DDC) was evaluated by two methods—comparison of self-reported accident rates from the year before and the year after DDC, and comparison of the after-DDC rates with those reported by other drivers who were not exposed to DDC but were driving at the same time. Official state records were also collected. Information was obtained from 8182 DDC graduates (study group) in 26 states who completed a survey describing their accident histories for the 12-month period before DDC. One year later. 72 per cent (5921) of these drivers responded to a similar self report for the 12-month period after DDC. At the time this after-DDC information was collected, comparison group information was obtained for 2397 drivers who entered the DDC program 1 year later. Official records from seven states were collected for approximately one third of the study and comparison group samples.

DDC graduates responding to the recontact questionnaire reported significant reductions of 32.8 per cent fewer accidents in the year after DDC as compared to the year before. The study group respondent accident rate was also significantly lower than the comparison group rate. Further analysis of self report data showed that reductions following DDC were greater for males than females and were less for those drivers 24 yr and under with females in this age group showing the least reductions after DDC. Accident profiles after DDC including type, severity, and manner of collision remained generally similar to before-DDC profiles, although there appeared to be a positive connection between course emphasis and the magnitude of reduction for different types of accidents. The study group showed a 17.6 per cent reduction in state-recorded accidents in the year after as compared with the year before DDC. The comparison group showed an increase of 11.9 per cent in state-recorded accidents over the same period. The reductions in state-recorded accidents after DDC for the study group were not significantly different from those of the comparison group, however, the results of the state-recorded analysis were viewed as supporting the significant decreases found in the self reports.     

Cannabis use and traffic accidents in a birth cohort of young adults

Objective: to examine linkages between cannabis use and traffic accident risks in a birth cohort of 907 young New Zealanders studied from 18 to 21 years. Methods: during the course of a 21-year longitudinal study of a birth cohort of 907 New Zealand born children information was gathered on (a) annual frequency of cannabis use over the period from 18 to 21 years; (b) annual rates of traffic accidents during the period 18–21 years; (c) measures of driver behaviours and characteristics. The association between cannabis use and traffic accident risk was examined among the 907 sample members who reported driving a motor vehicle between the ages of 18 and 21 years. Results: there were statistically significant relationships between reported annual cannabis use and annual accident rates. This association was present only for ‘active’ accidents in which driver behaviours contributed to the accident; those using cannabis more than 50 times per year had estimated rates of active accidents that were 1.6 (95% CI 1.2–2.0) times higher than the rate for non-users. However, statistical control for driver behaviours and characteristics related to cannabis use (drink driving behaviour; risky/illegal driving behaviours; driver attitudes; gender) eliminated the association between cannabis use and traffic accident risks. Conclusions: although cannabis use was associated with increased risks of traffic accidents among members of this birth cohort, these increased risks appear to reflect the characteristics of the young people who used cannabis rather than the effects of cannabis use on driver performance.     

The life cycle of the policy for preventing road accidents: an empirical example of the policy for reducing drunk driving crashes in Taipei

The purpose of this paper is to examine the temporal variation of the effect of preventive policy on reducing traffic accidents. The life cycle theory was introduced to describe the safety effect of the intervening policy over time. Poisson regression models with dummy-based and time-based specifications were used to evaluate the effect of an intervening policy over an observation period following its implementation. The policy of "Criminal sanction for drunk driving (CSFDD)" in Taipei city was evaluated as an empirical example to determine whether the temporal variation of safety effect happened to the CSFDD policy. The study results showed that alcohol consumption, arresting the drunk driving offenders, and the implementation of the CSFDD were the significant factors affecting the rate of occurrence of fatal accidents involving drunk driving. The effect of the CSFDD policy appeared to be a rapid initial response followed by a lower rate of decay. The existence of the life cycle implies that employing different observation periods following the implementation of a specific policy to evaluate its performance may obtain different effects. The results of this study are crucial for policy evaluation. The effects of safety policy should be carefully interpreted in order to avoid misleading the relevant authorities in coming to the wrong conclusions and as such make the wrong decisions.     

Young driver accidents in the UK: the influence of age, experience, and time of day

Young drivers, especially males, have relatively more accidents than other drivers. Young driver accidents also have somewhat different characteristics to those of other drivers; they include single vehicle accidents involving loss of control; excess speed for conditions; accidents during darkness; accidents on single carriageway rural roads; and accidents while making cross-flow turns (i.e. turning right in the UK, equivalent to a left turn in the US and continental Europe). A sample of over 3000 accident cases was considered from midland British police forces, involving drivers aged 17-25 years, and covering a two year period. Four types of accident were analysed: right-turns; rear-end shunts; loss of control on curves; and accidents in darkness. Loss of control on curves and accidents in darkness were found to be a particular problem for younger drivers. It was found that cross-flow turn accidents showed the quickest improvement with increasing driver experience, whereas accidents occurring in darkness with no street lighting showed the slowest rate of improvement. 'Time of day' analyses suggested that the problems of accidents in darkness are not a matter of visibility, but a consequence of the way young drivers use the roads at night. There appears to be a large number of accidents associated with voluntary risk-taking behaviours of young drivers in 'recreational' driving.     

An analysis of the severity and incident duration of truck-involved freeway accidents

Data associated with over 9000 accidents involving large trucks and combination vehicles during a two-year period on freeways in the greater Los Angeles area are analyzed relative to collision factors, accident severity, and incident duration and lane closures. Relationships between type of collision and accident characteristics are explored using log-linear models. The results point to significant differences in several immediate consequences of truck-related freeway accidents according to collision type. These differences are associated both with the severity of the accident, in terms of injuries and fatalities, as well as with the impact of the accident on system performance, in terms of incident duration and lane closures. Hit-object and broadside collisions were the most severe types in terms of fatalities and injuries, respectively, and single-vehicle accidents are relatively more severe than two-vehicle accidents. The durations of accident incidents were found to be log-normally distributed for homogeneous groups of truck accidents, categorized according to type of collision and, in some instances, severity. The longest durations are typically associated with overturns.     

Fatal traffic accidents among trailer truck drivers and accident causes as viewed by other truck drivers

Causality factors, the responsibility of the driver and driver fatigue-related factors were studied in fatal two-vehicle accidents where a trailer truck driver was involved during the period of 1991-1997 (n = 337). In addition, 251 long-haul truck drivers were surveyed in order to study their views regarding contributing factors in accidents involving trucks and the development of possible countermeasure against driver fatigue. Trailer truck drivers were principally responsible for 16% of all the accidents. Younger driver age and driving during evening hours were significant predictors of being principally responsible. In addition, the probability of being principally responsible for the accident increased by a factor of over three if the driver had a chronic illness. Prolonged driving preceding the accident, accident history or traffic offence history did not have a significant effect. Only 2% of the drivers were estimated to have fallen asleep while driving just prior to the accident, and altogether 4% of the drivers had been tired prior to the accident. Of the drivers 13% had however, been driving over 10 h preceding the accident (which has been criminally punishably in Finland since 1995 under the EC regulation) but no individual factors had a significant effect in predicting prolonged driving. The surveyed views regarding causes of truck accidents correspond well with the accident analysis. Accidents were viewed as being most often caused by other road users and driver fatigue was viewed to be no more than the fifth (out of eight) common cause of accidents. The probability of viewing fatigue as a more common cause increased significantly if the driver had experienced fatigue-related problems while driving. However, nearly half of the surveyed truck drivers expressed a negative view towards developing a technological countermeasure against driver fatigue. The negative view was not related to personal experiences of fatigue-related problems while driving.     

Systems thinking,the Swiss Cheese Model and accident analysis: A comparative systemic analysis of the Grayrigg train derailment using the ATSB,AcciMap and STAMP models

The Swiss Cheese Model (SCM) is the most popular accident causation model and is widely used throughout various industries. A debate exists in the research literature over whether the SCM remains a viable tool for accident analysis. Critics of the model suggest that it provides a sequential, oversimplified view of accidents. Conversely, proponents suggest that it embodies the concepts of systems theory, as per the contemporary systemic analysis techniques. The aim of this paper was to consider whether the SCM can provide a systems thinking approach and remain a viable option for accident analysis. To achieve this, the train derailment at Grayrigg was analysed with an SCM-based model (the ATSB accident investigation model) and two systemic accident analysis methods (AcciMap and STAMP). The analysis outputs and usage of the techniques were compared. The findings of the study showed that each model applied the systems thinking approach. However, the ATSB model and AcciMap graphically presented their findings in a more succinct manner, whereas STAMP more clearly embodied the concepts of systems theory. The study suggests that, whilst the selection of an analysis method is subject to trade-offs that practitioners and researchers must make, the SCM remains a viable model for accident analysis.