Full Bayesian evaluation of the safety effects of reducing the posted speed limit in urban residential area

Full Bayesian (FB) before–after evaluation is a newer approach than the empirical Bayesian (EB) evaluation in traffic safety research. While a number of earlier studies have conducted univariate and multivariate FB before–after safety evaluations and compared the results with the EB method, often contradictory conclusions have been drawn. To this end, the objectives of the current study were to (i) perform a before–after safety evaluation using both the univariate and multivariate FB methods in order to enhance our understanding of these methodologies, (ii) perform the EB evaluation and compare the results with those of the FB methods and (iii) apply the FB and EB methods to evaluate the safety effects of reducing the urban residential posted speed limit (PSL) for policy recommendation. In addition to three years of crash data for both the before and after periods, traffic volume, road geometry and other relevant data for both the treated and reference sites were collected and used. According to the model goodness-of-fit criteria, the current study found that the multivariate FB model for crash severities outperformed the univariate FB models. Moreover, in terms of statistical significance of the safety effects, the EB and FB methods led to opposite conclusions when the safety effects were relatively small with high standard deviation. Therefore, caution should be taken in drawing conclusions from the EB method. Based on the FB method, the PSL reduction was found effective in reducing crashes of all severities and thus is recommended for improving safety on urban residential collector roads.     

Investigation of the driving experience of a sample of Victorian learner drivers

This paper presents the results of an investigation of the driving experience of a small sample of learner drivers in Victoria, Australia. Participants (n = 110) kept a continuous logbook of their driving experience over the 2 years of the learner-driver period, including information about the distance and time of each driving trip, their level of confidence, and monthly data concerning the number of crashes, near misses, and unpleasant emotional interactions with their supervising driver. The analysis of these data suggests that learner drivers accrue relatively little driving experience and that they tend to obtain this experience in daytime, fair-weather driving. The implications of these results are discussed.     

The role of parents and non-parents in the supervision of learner drivers in Australia

The purpose of this study was to contrast the role of parental and non-parental (sibling, other family and non-family) supervisors in the supervision of learner drivers in graduated driver licensing systems. The sample consisted of 522 supervisors from the Australian states of Queensland (n = 204, 39%) and New South Wales (n = 318, 61%). The learner licence requirements in these two states are similar, although learners in Queensland are required to accrue 100 h of supervision in a log book while those in New South Wales are required to accrue 120 h. Approximately 50 per cent of the sample (n = 255) were parents of the learner driver while the remainder of the sample were either siblings (n = 72, 13.8%), other family members (n = 153, 29.3%) or non-family (n = 114, 21.8%). Parents were more likely than siblings, other family or non-family members to be the primary supervisor of the learner driver. Siblings provided fewer hours of practice when compared with other supervisor types while the median and mode suggest that parents provided the most hours of practice to learner drivers. This study demonstrates that non-parental supervisors, such as siblings, other family members and non-family, at least in jurisdictions that require 100 or 120 h of practice, are important in facilitating learner drivers to accumulate sufficient supervised driving practice.     

The licensing and safety of older drivers in Britain

Driving licence holding in Britain is increasing for older people, particularly older women. Licence holding by men aged 40–69 has saturated at about 90%, and for women aged 30–59 at about 78%. Drivers begin to surrender licences after age 70. By age 90, 38% of women and 25% of men who held a licence at age 70 have surrendered their licences.     

Effectiveness evaluation of simulative workshops for newly licensed drivers

The current study set to examine the effects of simulator use in driving instruction on newly licensed drivers, comparing the road safety knowledge and reported intended behavior, as well as the actual driving performance of new drivers. Participants consisted of 280 newly licensed driver, of which 140 whose drivers license training included additional simulator-based lessons, and 140 drivers whose training precluded simulator-based lessons. All drivers answered questionnaires pertaining to their intended safe driving behaviors (according to Ajzen's (2000) theory of planned behavior), and to their traffic safety knowledge. Of the initial sample, 40 drivers received actual driving performance evaluation by an expert driving instructor, as well as by in-vehicle data recorders (IVDRs). We assumed that safer drivers report safer driving intentions, demonstrate greater traffic safety knowledge, evaluated as safer drivers by the driving instructor, and display lower and stable driving parameters on the IVDRs. We hypothesized that theoretical driving studies combined with practical training on simulators will elevate the safety level of novices driving. Hierarchical regression analyses on driving intentions indicated that drivers who did not receive simulator-based lessons demonstrated safer driving intentions compared to drivers who received simulator-based lessons. This pattern possibly indicating the drivers who received simulator-based lessons felt more confident in their driving abilities compared to drivers who did not receive simulated training. No significant difference was found in traffic safety knowledge, or in the evaluation of the expert driving instructor. IDVR data comparisons indicated drivers who received simulator-based lessons braked more often and were less prone to headway events, suggesting a more responsive driving style. These findings do not point to any significant advantage or disadvantage of the current simulator-based driving training over other driving training methods.     

Comparison of age and sex characteristics of police-suspected impaired drivers and roadside-surveyed impaired drivers

The age and sex characteristics of drivers randomly stopped by police-conducted spot-checks and suspected of drinking were compared to drivers stopped and breath-tested during an independent roadside survey. Discrepancies were evident. A significantly higher proportion of younger drivers were requested to submit to a roadside screening device, yet a greater proportion of older drivers, particularly females, registered a “fail” (over 80 mg/100 ml). The results of the independent roadside survey of the same geographical region found no differences in the proportion of younger and older drivers with B.A.C.s over 80 mg. Although the nature of the study precludes firm conclusions being drawn, hypotheses are offered as interpretations of these findings.     

Analysis of truncation limit in probabilistic safety assessment

A truncation limit defines the boundaries of what is considered in the probabilistic safety assessment and what is neglected. The truncation limit that is the focus here is the truncation limit on the size of the minimal cut set contribution at which to cut off. A new method was developed, which defines truncation limit in probabilistic safety assessment. The method specifies truncation limits with more stringency than presenting existing documents dealing with truncation criteria in probabilistic safety assessment do. The results of this paper indicate that the truncation limits for more complex probabilistic safety assessments, which consist of larger number of basic events, should be more severe than presently recommended in existing documents if more accuracy is desired. The truncation limits defined by the new method reduce the relative errors of importance measures and produce more accurate results for probabilistic safety assessment applications. The reduced relative errors of importance measures can prevent situations, where the acceptability of change of equipment under investigation according to RG 1.174 would be shifted from region, where changes can be accepted, to region, where changes cannot be accepted, if the results would be calculated with smaller truncation limit.     

Factors associated with fatal and injurious car crash among learner drivers in New South Wales,Australia

This exploratory study investigated factors associated with car crash injury among learner drivers across difference ages by using data routinely collected by the NSW police. The results obtained indicated that some factors are commonly associated with car crash injury across nearly all ages. On the other hand, some others are more age specific. On the whole, female learner drivers were more at risk of being killed or injured as compared to males. The drivers of 16 years old had an increased risk of crash injury due to environmental factors, such as special road feature, and distraction outside the vehicle. The increased risk of crash injury for older drivers (> or =25 years) was associated with distractions from both inside and outside vehicle. Night time driving posed a special risk to learner drivers aged 20-24 years old, but not other age groups. Speeding was a common factor for the increased risk of crash injury across all age groups. The implication of the results and limitations of the study were discussed.     

Attitudes of commercial motor vehicle drivers towards safety belts

Despite the fact that Hawaii has one of the highest seat belt use rates for passenger vehicles in the United States, and has had a mandatory seat belt use law since the 1980s, studies have shown that commercial motor vehicles (CMV) seat belt use rates are low. To better understand this phenomenon, a comprehensive survey of commercial vehicle drivers was conducted in Hawaii to ascertain attitudes and self-reported behaviors regarding seat belt use. A total of 791 drivers responded to a written questionnaire implemented at weigh stations and distributed to various trucking firms and transport centers. Approximately 67% reported that they use seat belts “always” when driving a CMV (commercial motor vehicle), yet when asked how often do other CMV drivers use seat belts, only 31% responded “always.” Interestingly, 86% of these same drivers reported that they use seat belts “always” when driving a personal vehicle. The major reason cited for non-use of belts was “frequent stops/inconvenience” (29%), and “not safety conscious” (23%). Notably, the self-reported use of safety belts is highest among operators of vans (88% said “always”), followed by buses (87% said “always”) and lowest among truck drivers (only 60% said “always”). In this paper, some of the differences between self-reported users and non-users are explored and a multivariate logit model was developed to predict the odds of belt use as a function of various factors.     

Self-rated driving performance among elderly drivers referred for driving evaluation

PURPOSE: To explore whether elderly drivers of varying driving skill levels (1) differ in their perception of their driving evaluation performance and (2) determine if self-rated driving evaluation performance is related to cognitive ability. METHODS: One hundred and fifty-two drivers aged 65 years or older and referred for a driving evaluation were enrolled into the study. Subjects were asked the question, "how well do you think you will perform today on your driving evaluation compared to others your own age?" Subjects also completed the Mini-Mental State Exam and a 30-min drive on a STISIM Drivetrade mark simulation (Systems Technology, Inc., Hawthorne, CA). Only 47 subjects completed both the simulated drive and self-rated item. RESULTS: Sixty-five percent of drivers rated themselves as performing better on a driving test than others of their age. Another 31.9% felt they would perform the same as others of their age on a driving test. A 50.0% of those considering themselves "a little better" and 52.9% of those considering themselves "a lot better" had an unsafe driving performance. As self-rated driving evaluation performance increased, there was a significantly increased risk of unsafe driving (p=0.02) in the study population. Drivers who considered themselves at least a little better than others of their age were over four times more likely to be unsafe drivers compared to others who believed they were comparable to or worse than other drivers of their age (RR=4.13, 95% CI=1.08-15.78). There was no significant difference in MMSE between self-rating groups (p=0.76). CONCLUSION: Older drivers assign high ratings to their driving performance, even in the presence of suspected skill decline. Cognitive ability was not related to self-rated driving evaluation performance.     

Error specific restrictions for older drivers: promoting continued independence and public safety

OBJECTIVES: To describe a population of older drivers with driving restrictions, their most common restrictions, and to compare restricted drivers to their safe and unsafe counterparts. Safe drivers are those who do not commit hazardous errors or traffic violations. Unsafe drivers are those who commit hazardous errors and/or traffic violations that place them in hazardous situations. Restricted drivers are those who have committed traffic or rule violations only under certain driving conditions. DESIGN: A retrospective, cross-sectional study with mixed methodology. SETTING: A clinical driving evaluation program within an academic geriatrics department. PARTICIPANTS: Drivers age 60+ (N=108) referred for clinical driving evaluation and who consented to allow their data to be used for research purposes. INTERVENTION: Drivers performing at an intermediate level driving fitness were issued error specific driving restrictions. MEASUREMENT: Driving evaluation included clock drawing test (CDT), mini-mental status exam (MMSE), Trailmaking, geriatric depression scale (GDS), and simulated driving. RESULTS: The three most common restrictions were limited driving distance (N=8), limited driving time (N=8), and daytime only driving (N=8). Safe, restricted, and unsafe drivers significantly differed on MMSE (F[2,104]=10.75, p<0.001), Trailmaking Part B (F[2,76]=9.96, p<0.001), CDT (F[2,98]=29.88, p<0.001), and total number of hazardous errors (F[2,97]=39.06, p<0.001). Tukey's test indicated safe and restricted drivers scored significantly better than unsafe drivers on MMSE (safe: p<0.001; restricted: p=0.008), CDT (p<0.001), and hazardous errors (p<0.001). Restricted and unsafe drivers required significantly more time to complete Trailmaking B than safe drivers (p=0.004). CONCLUSION: Preliminary data indicate restricted drivers perform more like safe than unsafe drivers. Driving simulation is instrumental in discerning error specific limitations and categorizing patients as conditionally safe. This clinical evaluation pilots an effective alternative to premature driving cessation.     

Age-related safety in professional heavy vehicle drivers: A literature review

With Australia facing a looming shortage of heavy vehicle drivers the question is raised as to whether it is desirable or prudent to encourage older professional heavy vehicle drivers to remain in the transport sector for longer, particularly those of heavy vehicles or recruit drivers of a younger age.

Aim

To review age-related safety and identify other factors that contribute to accidents experienced by heavy vehicle drivers.

Methods

A search was conducted of national and international peer-reviewed literature in the following databases: MedLine, Embase, Cinahl, PsychInfo and the Canadian Centre for Occupational Health & Safety. A manual search was performed to obtain relevant articles within selected journals.

Results

A limited number of studies reported age-specific accident rates for heavy vehicles for the spectrum of driver age that included drivers younger than 27 years and those over 60 years of age. Heavy vehicle drivers younger than 27 years of age demonstrated higher rates of accident/fatality involvement which decline and plateau until the age of 63 years where increased rates were again observed. Other contributing factors to heavy vehicle accidents include: long hours and subsequent sleepiness and fatigue, employer safety culture, vehicle configuration particularly multiple trailers, urbanisation and road classification.

Conclusions

Drivers of heavy vehicles are over-involved until age 27 years however a characteristic ‘U’ shaped curve indicates a higher risk of accident involvement for both younger and older drivers. More detailed analyses of “at-fault” involvement and inability to avert an accident and other factors that contribute to accidents across the ages of heavy vehicle drivers may give further clarification to the degree of safety of both younger and older commercial heavy vehicle drivers.     

Sleepiness in professional drivers: effect of age and time of day

The effect of age and time of day on objective and subjective sleepiness in professional drivers was investigated during a simulated driving task. Thirty-six young and middle-aged professional males drivers, free from any sleep disorder, took part in two simulated driving sessions; one carried out in the afternoon (between 2 and 4 p.m.) the other in the evening (between 11 p.m. and 1 a.m.). Half of each age group drove in a low traffic condition while the second half drove in a heavy traffic condition. Throughout the driving task, subjects' electroencephalogram and Karolinska sleepiness scale (KSS) scores were recorded. Visual analog scales measuring alertness and sleepiness levels were also completed before and after the driving. After each session, subjects filled out the NASA-TLX questionnaire and were asked if they had felt sleepy during the driving. Young professional drivers presented a significant decrease in alertness (raise of the spectral power in the alpha band) in the low traffic condition and a strong propensity to sleep during the evening test in contrast to middle-aged professional drivers.     

The relationship of alcohol safety laws to drinking drivers in fatal crashes

This paper presents an analysis of the relationships between the passage of key alcohol safety laws and the number of drinking drivers in fatal crashes. The study evaluated three major alcohol safety laws--administrative license revocation laws, 0.10 illegal per se, and 0.08 illegal per se laws--on the proportion of drinking drivers in fatal crashes. Drivers aged 21 and older in fatal crashes at two BAC levels--0.01-0.09 and 0.10 or greater--were considered separately. Drivers under age 21 were not included because they are affected by the Minimum Legal Drinking Age (MLDA) law. This study used data on drinking drivers in fatal crashes from the Fatality Analysis Reporting System (FARS) covering 16 years (1982-1997) for all 50 states and the District of Columbia. Also included in the study were such variables as per capita alcohol consumption and annual vehicle miles traveled (VMT), which could affect the number of alcohol-related crashes. The results indicate that each of the three laws had a significant relationship to the downward trend in alcohol-related fatal crashes in the United States over that period. This paper points out that this long-term trend is not the product of a single law. Instead, it is the result of the growing impact of several laws over time plus the affect of some factors not included in the model tested (such as the increasing use of sobriety checkpoints and the media's attention to the drinking-and-driving problem).     

Cognitive screening of older drivers does not produce safety benefits

Although screening policies for older drivers based on chronological age are widely used in many countries, previous research has shown that increasing age does not cause higher crash rates and that consequently, chronological age per se is at best only a weak predictor of safe driving performance. Previous research on age-based mandatory screening of older drivers has not been able to demonstrate any safety benefits from screening measures.     

Fracture limit prediction for a double safety structure in cylindrical-type lithium secondary batteries

In this study, a double safety structure used for cylindrical-type lithium secondary batteries is newly introduced. The structure is necessary to prevent users and the cylindrical-type secondary batteries from unpredictable explosions due to a temporary increase in the inner pressure of the batteries. The double safety structure consists of a primary safety component as micro half-blanked component, and a secondary safety device as V-notched part. For the double safety device, both the mentioned components are considered by the micro half-blanking and the V-notch forming processes with numerical and experimental predictions for the fracture limit. The mechanical properties are investigated with both a raw and an annealed thin sheet material of 1050-H16 aluminum alloy. The main process parameters are considered to be the clearance and punch-die corner radius for the micro half-blanking process, and the remaining thickness, tip radius, and shape angle of the V-notch. In this study, finite element simulations are carried out to verify the manufacturing process with the mentioned process parameters. The ductile fracture criterion is also adopted to predict the fracture limit for each component. Furthermore, experimental investigations are included to verify the fracture limit predicted from the numerical approach. From the systematic approaches, it is confirmed that the fracture limit for the double safety structure is well predicted, and satisfies the required fracture limit.     

Gender differences among older drivers in a comprehensive driving evaluation

Research studies typically consider older drivers as a homogenous group and do not report on the influence of gender on driving performance. Prior studies report that females are over-represented in crashes compared to males, caused by errors of yielding, gap acceptance, and speed regulation, all of which are assessed in a comprehensive driving evaluation (CDE). In a sample of 294 community dwelling older drivers, we examined and compared specific and total driving errors of both genders, and determined predictors of gender-specific driving errors and pass/fail outcomes who completed a CDE assessed by a certified driving rehabilitation specialist. No differences in specific or total number of driving errors on the CDE were found between older males (Mean age 73.4 ± 6.0) and older females (Mean age 73.8 ± 5.7). Education, days of driving, Useful Field of View™ (UFOV), Rapid Paced Walk Test (RPW) and the Mini-Mental State Exam (MMSE) were all independent predictors of failing a road test for both genders (p < 0.05). However, older females were 22% less likely than older males to fail an on-road test. Within group comparisons showed that older males and females >75 years were 3.2 and 3.5 times more likely to fail the on-road test compared to younger males and females (aged between 63 and 75), respectively. Our findings suggest that focusing on older old (75+) and old–old (85+) age groups may be more efficient for future investigations of driving performance.     

A systems model for safety program evaluation

A system of program evaluation is presented that examines organizational and programmatic aspects of countermeasures as well as three levels of outcome. Level one outcomes include changes in skills, knowledge, attitudes and resources. Change in behavior is the level two outcome. The ultimate or level three outcomes are increased cost effectiveness and reduction in death, disability, discomfort, dissatisfaction and deleterious side effects. Evaluation often requires assessment of level one and two outcomes for gatekeepers as well as for the ultimate population to be reached. Attention also must be paid to separate analysis of high vs low risk situations for injury events. The time series approach to evaluation should be used only on those rare occasions where it is not feasible to apply two by two design or its modifications.     

An evaluation of the specific deterrent effects of vehicle impoundment on suspended, revoked, and unlicensed drivers in California

There have been a number of studies conducted during the past two decades that convincingly demonstrate that license suspension and revocation are some of the most effective countermeasures currently available for attenuating the traffic safety risk of problem drivers. At the same time, it is also known that most suspended/revoked (S/R) drivers violate their illegal driving status and continue to drive, accruing traffic convictions and becoming involved in crashes. In an attempt to strengthen license actions and to better control S/R and unlicensed drivers, California enacted two laws effective January 1995 which provide for the impoundment and forfeiture of vehicles driven by S/R and unlicensed drivers. The study described in this paper evaluates the impact of vehicle impoundment on the 1-year subsequent driving behavior of S/R and unlicensed drivers who experience this sanction. The results show that drivers with no prior convictions for driving while S/R or unlicensed whose vehicles were impounded have, relative to similar drivers whose vehicles were not impounded: 23.8% fewer driving while suspended/revoked or unlicensed convictions; 18.1% fewer traffic convictions; and 24.7% fewer crashes. The differences between the impound and no-impound groups are even larger when the driving records of repeat offenders (i.e. drivers with prior driving-while-S/R or unlicensed convictions) are examined. Repeat offenders whose vehicles are impounded have 34.2% fewer driving-while-S/R or unlicensed convictions, 22.3% fewer traffic convictions and 37.6% fewer crashes. These findings provide strong support for impounding vehicles driven by S/R and unlicensed drivers.     

Road safety effects of porous asphalt: a systematic review of evaluation studies

This paper presents a systematic review of studies that have evaluated the effects on road safety of porous asphalt. Porous asphalt is widely used on motorways in Europe, mainly in order to reduce traffic noise and increase road capacity. A meta-analysis was made of six studies, containing a total of eighteen estimates of the effect of porous asphalt on accident rates. No clear effect on road safety of porous asphalt was found. All summary estimates of effect indicated very small changes in accident rates and very few were statistically significant at conventional levels. Studies that have evaluated the effects of porous asphalt on nine different risk factors associated with accident occurrence were also reviewed. It was found that four of the risk factors were favourably influenced by porous asphalt, three were adversely influenced, and two were not influenced by porous asphalt. The net impact of these changes in risk factors on accident occurrence cannot be predicted. On the whole, the research that has been reported so far regarding road safety effects of porous asphalt is inconclusive. The studies are not of high quality and the findings are inconsistent.