Tiredness! a natural explanation to The Grand Rapid "DIP"

The present analysis deals with the presumed improved driving skill of car drivers with low blood alcohol concentrations (BACs) compared to the driving skill of sober drivers. Several roadside surveys indicate such a controversial possibility, which is illustrated graphically in "The Grand Rapid Study" (1964) as a relative accident risk curve for driving while intoxicated (DWI). A curve which shows a "DIP" below a baseline accident risk of one for sober drivers in the interval between BACs of 0.01 and 0.04 g/l. Since then, various attempts have been made to show this "DIP" in the otherwise "exponentially" raising curve to be an artificial distortion based on disproportionate demographic subgroups. It is, however, our thesis that the observations of "The Grand Rapid Study" and other roadside surveys are valid, because the presumed mono-causal traffic accident curve hides "tiredness" as an additional human risk factor. This makes the first part of the night-time relative accident risk curve for impaired drivers artificially augmented by "tired" drivers with insignificant amounts of alcohol in the blood and therefore incorrectly accused of accidents due to DWI. The accident risk curve for higher BACs raises similarly abrupt due to drivers impaired by a combined effect of alcohol and "tiredness". Moreover, to imply an accident risk of one for all sober drivers independent of the time of the day is debatable as an increased accident risk is present in the late night-time hours due to "tired" drivers. This increase in "tired" sober accident drivers suppresses the accident risk curve for DWI with BACs of 0.01-0.04 g/l below the fixed baseline of one for the background population.     

Reductions in driver speed using posted feedback of speeding information: social comparison or implied surveillance?

Reducing driver speed has an essential role to play in traffic safety. This study measured the effect of a roadside sign, in a 50 km/h zone, that consecutively displayed one of three messages:

1. The average speed at the site: this message was designed to induce “social comparison” whereby drivers may reduce their speed in order to comply with the behaviour of the majority.

2. A warning that drivers’ speeds were being measured: this was intended to imply surveillance whereby drivers may reduce speed in order to avoid possible enforcement action.

3. A combination of both messages, to see if both together would have a greater effect than either alone.

The speed of drivers travelling along a busy urban road (11,500 cars daily in each direction) was measured using inductive loop detectors. The proportion of drivers travelling 60 km/h or less increased with all three messages, suggesting that both social comparison and implied surveillance are mechanisms by which driver speed may be reduced. However, the speed reductions were not as great as in previous studies of feedback signs. This may be due to differences in the existing safety culture.     

A study of driver experience and vehicle familiarity in accidents

A separate study was performed as part of a major accident investigation project to (1) test the hypothesis that drivers of vehicles involved in investigated accidents had less driving experience than the general driving population, and (2) test the hypothesis that accident involved drivers were less familiar with their vehicles than the general driving population. A Kolmogorov-Smirnov one-tail test was employed to evaluate the differences in the distributions of driver experience and vehicle familiarity between the “accident sample” and a “control sample.” Results indicated that drivers involved in the investigated accidents had less driving experience in general and had less driving experience with the accident vehicles than drivers in the general population. These effects are discussed briefly and further studies are suggested.     

A modeling perspective on the culture of driving

Each driver is influenced by the collective behavior of other drivers. At the same time, each driver is also part of this collective, and thus influences others. Underlying many driver control and traffic safety programs are two implicit and related assumptions: that drivers are sensitive to the “culture of driving” around them and emulate it; and, that a small shift in the behavior of few might be amplified or snowball to a much larger effect resulting in a changed traffic environment or a modified culture of driving. The paper discusses possible mechanisms for the interactions between individuals, collectives, and culture, drawing on literature from social psychology, sociology, economics, communication, epidemiology, and other disciplines. Traffic behavior modeling could benefit from considering concepts developed in other social disciplines while providing challenging research issues and data sources for testing and developing those concepts.     

Driver irritation and aggressive behaviour

A sample of 98 drivers responded to a Swedish version of the UK Driving Anger Scale [UK DAS; [Lajunen, T., Parker, D., Stradling, S.G., 1998. Dimensions of driver anger, aggressive and highway code violations and their mediation by safety orientation in UK drivers. Transport. Res. Part F 1, 107–121]. The results indicated that the Swedish version, like the British original, measures three sources of driver irritation: “progress impeded”, “reckless driving”, and “direct hostility”. Structural equation modelling was used to investigate the relationships between the three sources of self-reported driver irritation, aggressive actions, speed, sex, age, and annual mileage. The models suggested a positive relationship between the amount of driver irritation and frequency of aggressive actions for all three sources of irritation. Female drivers tended to become more irritated than male drivers, while the male drivers tended to act aggressively more often. Surprisingly, drivers who reported that they enjoy fast speeds did not become more irritated than slower drivers when obstructed. The important conclusions are that experienced irritation often leads to openly aggressively actions, and that expression of aggressive behaviours may be a cause of other drivers’ feeling of irritation.     

Looked-but-failed-to-see-errors in traffic

Danish studies of traffic accidents at priority intersections have shown a particular type of accidents. In these accidents a car driver supposed to give way has collided with a bicycle rider on the priority road. Often the involved car drivers have maintained that they did not see the bicycle until immediately before the collision even though the bicycle must have been clearly visible.

Similar types of accidents have been the subject of studies elsewhere. In literature they are labelled “looked-but-failed-to-see”, because it seems clear that in many cases the car drivers have actually been looking in the direction where the other parties were but have not seen (i.e. perceived the presence of) the other road user. This paper describes two studies approaching this problem.

One study is based on 10 self-reported near accidents. It does show that “looked-but-failed-to-see” events do occur, especially for well experienced drivers. The other study based on Gap Acceptance shows that the car driver acceptance of gaps towards cyclists depends on whether or not another car is present. Hypotheses for driver perception and for accident countermeasures are discussed.     

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.     

Less is more: the influence of traffic count on drinking and driving behaviour

Drinking and driving road checks are often organized with either a clear prevention or repression objective in mind. The objective of a prevention strategy is to make as many people as possible believe that police officers are enforcing drinking and driving laws and that drinking drivers will most likely be caught. As such, targeting high traffic count road sites with high-visibility road checks is a priority because it serves to increase awareness of the enforcement activity. An alternative to this prevention approach is the “repression” approach that involves targeting times and places where the highest number of drinking drivers are to be expected. Rather than attempting to affect the subjective chance of getting caught, this approach seeks to increase the objective likelihood of getting caught; the aim is to apprehend as many drinking drivers as possible. Regardless of the chosen strategy, there is a need to understand how traffic count influences drinking and driving behaviour as traffic count may play a role in a police officer's choice of sites for a road check. The objective of this paper is to shed some light on this relationship between drinking and driving behaviour and traffic count. In this paper, data from a roadside survey, carried out in British Columbia in 2003, are used. A two-level logistic regression analysis was carried out with data from 2627 drivers coming from 48 different road sites to replicate a model that was previously obtained with comparable data from a Belgian roadside survey, also carried out in 2003. The present study successfully replicated the findings of the Belgian model, substantiating that the probability for drivers to be drinking and driving significantly decreases with an increasing level of traffic count. This supports the suggestion that drinking drivers avoid high traffic count road sites. The relevance of these findings with respect to organizing preventive or repressive road checks and possible confounding variables are discussed at the end of this paper.     

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.     

Effects of measurement assumptions on estimations of risk of collision

This paper provides a replication and extension of previous research describing the relationship between risk of fatal collision and driver blood alcohol content. Risk of collision indices are derived through a comparison of the blood alcohol levels of nighttime Canadian drivers and nighttime driver fatalities. In the context of these data sets an assessment is made of the effects of different treatments of missing data upon estimations of risk of collision. Assumptions regarding the distribution of alcohol among non-respondents in roadside surveys, as well as among driver fatalities who are not tested for alcohol, are shown to have substantial implications for the magnitude of the risk factors derived. Nevertheless, although the magnitude of the relationship between driver blood alcohol and risk of fatal collision varies as a function of the assumptions utilized, the directionality of the relationship corresponds consistently to the results reported in previous investigations.     

Convicted of fatigued driving: Who, why and how?

Fatigue is a major cause of road traffic accidents. However, due to the blurred concept of fatigue and the lack of reliable testing devices (cf. the breath analyzer for alcohol levels), it is extremely difficult to incorporate fatigue in operationalized terms into either traffic or criminal law. Even though the Finnish Road Traffic Act explicitly forbids driving while tired, it is done only on a general level among other factors (sickness, etc.) that impair a driver's fitness to drive (Article 63). The present study was done to investigate the circumstances of fatigue driving offenses. From the Finnish Vehicle Administration driver record database we extracted all drivers (N = 768) punished under Article 63 from 2004-2005. Of these drivers, 90.4% committed a fatigue-related traffic offense. Accidents, predominantly single vehicle, were the most common (92.5%) consequence of fatigued driving. Although fatigue-related accidents are thought to be serious, our data shows that most of the accidents (81.6%) did not involve personal injuries. Almost every twentieth driver was punished because his vehicle was drifting on the road. The presence of alcohol or drugs was noted in 13% of the cases. Only 3.1% of the punished drivers officially denied being tired or falling asleep. Young men (≤35 yrs) represented 50% of all punished drivers. Time of day and seasonal effects were clear in this data. This study shows that even without a reliable fatigue detector and unambiguous criteria for recognizing the contribution of fatigue to accident causation, Finnish police and the courts punish a significant number of drivers every year on the basis of fatigue.     

Characteristics of crashes attributed to the driver having fallen asleep

While it has been known for some time that crashes can result from the driver falling asleep at the wheel, this issue has received less attention in traffic safety programs than the role of alcohol or speed of the vehicle. The present study was done to investigate the characteristics of crashes attributed to the driver being asleep. The study utilized the database at the Highway Safety Research Center at the University of North Carolina that is based on the uniform crash reporting system in that state. Over the years 1990–1992, inclusive, there were 4333 crashes in which the driver was judged to be asleep but not intoxicated. The crashes were primarily of the drive-off-the-road type (78% of the total) and took place at higher speeds (62% in excess of 50 mph). The fatality rate was of similar magnitude to that in alcohol-related crashes with fatalities in 1.4% of such crashes (alcohol crashes had fatalities in 2.1%). The crashes occurred primarily at two times of day—during the nighttime period of increased sleepiness (midnight to 7.00 a.m.) and during the mid-afternoon “siesta” time of increased sleepiness (3.00 p.m.). These crashes occurred predominately in young people. Fifty-five percent of these were in individuals 25 years of age or younger, with a peak age of occurrence at age 20 years. Sleepiness may play a role in crashes other than those attributed by the police to the driver being asleep. Determining the magnitude of this role is a challenge to the traffic safety community.     

Driver age, car mass and accident exposure— A synthesis of available data

The tendency of younger drivers to be more likely than older drivers to drive smaller cars has been an important consideration in a number of prior investigations of the relation between car size and traffic safety. The purpose of the present study is to quantify this effect on a firmer basis than hitherto by fitting data from seven independent sources to a unified general model. More specifically, when the exposure measures “per unit distance of travel” or “per registered car” are used in studies of car mass effects on traffic safety, the exposure information often does not contain the variable driver age. This work develops a general procedure for disaggregating such exposure data into three driver (or owner) age categories; A₁: 16–24; A₂: 25–34; and A₃: 35 years. Data from the seven sources are fined to the equation

f(i,m) = H_i[1 + G _i(m/900 − 1)]

where m is the ear mass in kg, and f(i,m) is the fraction of cars of mass m which are driven (owned) by persons in the A_i, (i = 1, 2, 3) age category. The form of this equation permits easy comparison of 900 and 1800 kg cars. Those particular masses that have been chosen for illustrative comparisons in earlier work. The seven sets of data are used to derive overall average values of the parameters H₁ and G₁. The data from all seven sources show consistent effects which are summarized in one analytical expression which is well suited for use in future studies of car size effects because it reflects a synthesis of much prior data and it permits sensitivity analyses to be performed conveniently.     

Limits of the quasi-induced exposure method when compared with the standard case-control design. Application to the estimation of risks associated with driving under the influence of cannabis or alcohol

The disparities between the quasi-induced exposure (QIE) method and a standard case–control approach with crash responsibility as disease of interest are studied. The 10,748 drivers who had been given compulsory cannabis and alcohol tests subsequent to involvement in a fatal crash in France between 2001 and 2003 were used to compare the two approaches. Odds ratios were assessed using conditional and unconditional logistic regressions. While both approaches found that drivers under the influence of alcohol or cannabis increased the risk of causing a fatal crash, the two approaches are not equivalent. They differ mainly with regards to the driver sample selected. The QIE method results in splitting the overall road safety issue into two sub-studies: a matched case–control study dealing with two-vehicle crashes and a case–control study dealing with single-vehicle crashes but with a specific control group. Using a specific generic term such as “QIE method” should not hide the real underlying epidemiological design. On the contrary, the standard case–control approach studies drivers involved in all type of crashes whatever the distribution of the responsibility in each crash. This method also known as “responsibility analysis” is the most relevant for assessing the overall road safety implications of a driver characteristic.     

驾驶员行为对交通噪声的影响

基于微观交通流仿真，结合ASJ-RTN 2008单车噪声排放模型，研究驾驶员行为对交通噪声的影响。通过敏感性分析得知，拥堵状态下的交通噪声对驾驶员跟驰行为和信号反应较为敏感，其中跟驰行为对交通噪声影响高达2.07 dB；而在畅通状态下，驾驶员行为对交通噪声的影响极小。受驾驶员行为变化的影响，区域噪声排放总能量与路旁L Aeq值的变化趋势相似，单位出行里程噪声排放能量与路旁L Aeq值的变化趋势相反。     

Feasibility of force platform based roadside drowsiness screening – A pilot study

Previous research on driver drowsiness detection has focused on developing in-car systems that continuously monitor the driver while driving and warn him/her when drowsiness compromises safety. In occupational settings a simple test of postural control has showed sensitivity to work shift induced fatigue in drivers. Whether the test is feasible for surveillance purposes in roadside settings is unknown. The present research sought to evaluate the feasibility of using a force platform test of postural control as a breathalyzer-like drowsiness-test at the roadside.     

A prevention programme for drinking driving

A drinking-driving programme introduced in one borough of Toronto, Canada, is evaluated. Based on evidence from previous programmes judged effective, it combined a highly visible “random” spot-check enforcement component with a drinking-driving educational component. A three-wave telephone survey showed significant increases in public knowledge of drinking and driving and of the programme in the experimental area. The subjective perception of arrest risk was increased for the “average driver” but not for “myself”. Unfortunately, only indirect evidence was available on driver behaviour and this tended to indicate fewer impaired drivers on the road. Finally, police reported alcohol-related accidents and injuries indicated an overall downward trend in Toronto, but the urban nature and restricted size of the experiment's geographic unit, as well as similar changes in control areas and contaminations to the data rendered the analysis highly ambiguous. Thus, the programme experienced some positive although by no means conclusive indicators of success.     

The role of exposure, experience and demerit point levels in the risk of collision

To study the relationships between exposure, collisions, and certain characteristics of drivers, a survey of approximately 3000 licensed drivers was carried out among residents of Toronto, Canada. Drivers were chosen randomly from the file of licensed drivers for both sexes at different levels of demerit points. Telephone interviews were used to collect data on the amounts and type of driving done in the previous week. These results and the collision experience of interviewed drivers were used to calculate annual collision rates per million driver-km. These rates were used to calculate the number of collisions expected to occur given the amounts of driving reported on certain types of road and times of day. Comparison of these figures with the number of collisions actually experienced in these circumstances indicated an increased hazard of city streets for all drivers and increased hazard of driving after dark for older drivers. The level of demerit points—indicator of the driver's recent conviction for traffic violations—was not associated with risk of collision if exposure was accounted for, except in drivers who typically drove small amounts. These results suggest that experience is an important benefit of high exposure for many drivers and may protect them from collisions in some circumstances. This has implications for the training and licensing of new drivers and for the need for continuing education of “high risk” drivers with low exposure.     

Factors affecting the probability of bus drivers being at-fault in bus-involved accidents

Previous research has provided little insight into factors that influence the probability of bus drivers being at-fault in bus-involved accidents. In this study, an analysis was conducted on accident data compiled by a bus company that include an assessment on whether the bus driver was deemed by the company to hold primary responsibility for accident occurrence. Using a mixed logit modelling approach, roadway/environmental, vehicle and driver related variables that were identified to be influential were road type, speed limit, traffic/lighting conditions, bus priority, bus age/length and driver's age/gender/experience/historic at-fault accident record. Results were indicative of possible confined road-space issues that bus drivers face along routes with roadside traffic friction and point to the provision of exclusive right of way for buses as a possible way to address this. Results also suggest benefits in assigning routes comprising mainly divided roads as well as newer and shorter buses to less experienced drivers.     

Young men in the arms of the law: An Australian perspective on policing and punishing the drinking driver

It is the thesis of this paper that young men, particularly those of an unskilled occupational status, are subject to more intensive surveillance by the police and more severe punishments for drinking and driving than other groups of road users. Evidence for this proposition is presented, drawing upon roadside survey, conviction, sentencing and police data on the ways in which drivers come to notice for a screening breath test. It is argued that the power granted to police and magistrates to exercise discretion in the performance of their duties has a pervasive influence in the production of the conviction and sentencing statistics, although road user characteristics (such as the times and frequency of driving) are of primary importance. It is hypothesized that police and magistrates tend to see young (unskilled) male drink-drivers as a greater threat to public safety than other classes of drinking drivers, and therefore these offenders are not as readily redefined as “folk criminals” and accorded lenient treatment. Although the value to road safety of this tough approach to young men is largely unknown, available evidence suggests that it may be limited.