Quantifying drivers’ comfort-zone and dread-zone boundaries in left turn across path/opposite direction (LTAP/OD) scenarios

The aim of this study is to quantify drivers’ comfort- and dread-zone boundaries in left-turn-across-path/opposite-direction (LTAP/OD) scenarios. These scenarios account for a large fraction of traffic fatalities world-wide. The comfort zone is a dynamic spatiotemporal envelope surrounding the vehicle, within which drivers feel comfortable and safe. The dread zone, a novel concept, describes a zone with a smaller safety margin that drivers will not voluntarily enter, but can push themselves into when conditions provide additional motivation (e.g., when hurried). Quantifying comfort- and dread-zone boundaries in the context of turning left before or after an oncoming vehicle has the potential to inform and improve both the design and driver acceptance of advanced driver assistance systems (ADAS) and autonomous vehicles.Using a within-subject design, a test-track experiment was conducted with drivers turning an instrumented vehicle left across the path of an oncoming vehicle. The oncoming vehicle was a self-propelled full-sized computer-controlled balloon vehicle going straight at a constant speed (50 km/h). The driver assumed full control of the instrumented vehicle approximately 20 m before the intersection and had to make the decision to turn left before or after the oncoming balloon vehicle. There were two experimental conditions, comfortable driving and hurried driving. Measures for each turn included post-encroachment time (PET), lateral acceleration, and self-reports of comfort and risk. Drivers consistently accepted shorter time gaps and higher lateral accelerations when hurried. We interpret these findings to suggest that drivers invoke two dynamic, contextually-defined safety margins. The first is the comfort-zone boundary, a limit which drivers do not voluntarily cross without extra motives. The second is the dread-zone boundary, a more distant limit which drivers do not voluntarily cross even with extra motives. Grouping the responses (high/low) to the driver behavior questionnaire (DBQ) improved the ability to predict the dread-zone boundary PET given the comfort-zone boundary PET.     

Driving manoeuvre during lane maintenance in older adults: Associations with neuropsychological scores

Older drivers experience difficulties in lane maintenance under challenging driving sections due to age-related cognitive declines, yet there is little comprehensive evidence on associations between cognitive functions and the lane maintenance in this population. In this study, fifty older drivers completed an on-road driving assessment and a battery of standard neuropsychological tests. Mean Lane Position (MLP), Standard Deviation of Lane Position (SDLP) and manoeuvre time calculated from precise vehicle movement trajectories were used as the lane maintenance parameters. The GNSS tracking vehicle movement presents comprehensive and reliable vehicle position data, which is more sensitive for detecting subtle variations of lane maintenance in older drivers. Statistical analysis results showed that lower visual attention (selective and divided attention) was associated with higher MLP and SDLP; MLP was also correlated to spatial abilities, executive function, and motor speed; manoeuvre time was negatively correlated with drivers’ risk-taking personality (all p < .01). Selective attention was found to be the best predictor of MLP in lane maintenance. A combined eight variables from three neuropsychological tests, UFOV 2 and 3, BD and BJLO, D-KEFS TMT 1, 2, 3, and 4, correctly classified 80.4% of participants with good versus low-performing lane maintenance.     

Are driving simulators effective tools for evaluating novice drivers’ hazard anticipation,speed management,and attention maintenance skills?

Novice drivers (teen drivers with their solo license for 6 months or less) are at a greatly inflated risk of crashing. Post hoc analyses of police accident reports indicate that novice drivers fail to anticipate hazards, manage their speed, and maintain attention. These skills are much too broadly defined to be of much help in training. Recently, however, driving simulators have been used to identify those skills which differentiate the novice drivers from older, more experienced drivers in the areas of hazard anticipation and speed management. Below, we report an experiment on a driving simulator which compares novice and experienced drivers’ performance in the third area believed to contribute especially heavily to crashes among novice drivers: attention to the forward roadway. The results indicate that novice drivers are much more willing to glance for long periods of time inside the vehicle than are experienced drivers. Interestingly, the results also indicate that both novice and experienced drivers spend equal amounts of time glancing at tasks external to the vehicle and in the periphery. Moreover, just as a program has been designed to train the scanning skills that clearly differentiate novice from experienced drivers, one might hope that a training program could be designed to improve the attention maintenance skills of novice drivers. We report on the initial piloting of just such a training program. Finally, we address a question that has long been debated in the literature: Do the results from driving simulators generalize to the real world? We argue that in the case of hazard anticipation, speed management, and attention maintenance the answer is yes.     

Social Psychological Models of Choice Behavior and Drivers' Left Turns

Abstract

The authors reanalyzed data from a simulated left-turn experiment (P. A. Hancock, J. K. Caird, S. Shekhar, & M. Vercruyssen, 1991) to test the adequacy of the nonlinear Gray-Tallman satisfaction balance model of choice behavior (L. N. Gray & I. Tallman, 1984) in predicting left turns. Participants (Hancock et al., 1991) were 40 experienced U.S. drivers who were exposed to simulated oncoming traffic; the size of the vehicle (motorcycle, compact vehicle, full-sized vehicle, delivery truck), its speed (10-70 mph, or 16-112 kmph), and the intervehicle time gap (3-9 s) varied. Hancock et al. (1991) measured (a) the likelihood of a left turn and (b) the occurrence of a collision. The probability of a left turn was greater for larger intervehicle time gaps and for oncoming smaller vehicles traveling at higher speeds. The Gray-Tallman (1984) model explained 69% of the variation in turning versus 57% for a linear regression model. In making decisions people tend to treat the values and costs affecting choices in a multiplicative, rather than linear, fashion. The Gray-Tallman model also has the potential for incorporating, both theoretically and mathematically, an unlimited range of potential values and costs that may influence left turn decisions.     

Social psychological models of choice behavior and drivers' left turns

ABSTRACT. The authors reanalyzed data from a simulated left-turn experiment (P. A. Hancock, J. K. Caird, S. Shekhar, & M. Vercruyssen, 1991) to test the adequacy of the nonlinear Gray-Tallman satisfaction balance model of choice behavior (L. N. Gray & I. Tallman, 1984) in predicting left turns. Participants (Hancock et al., 1991) were 40 experienced U.S. drivers who were exposed to simulated oncoming traffic; the size of the vehicle (motorcycle, compact vehicle, full-sized vehicle, delivery truck), its speed (10-70 mph, or 16-112 kmph), and the intervehicle time gap (3-9 s) varied. Hancock et al. (1991) measured (a) the likelihood of a left turn and (b) the occurrence of a collision. The probability of a left turn was greater for larger intervehicle time gaps and for oncoming smaller vehicles traveling at higher speeds. The Gray-Tallman (1984) model explained 69% of the variation in turning versus 57% for a linear regression model. In making decisions people tend to treat the values and costs affecting choices in a multiplicative, rather than linear, fashion. The Gray-Tallman model also has the potential for incorporating, both theoretically and mathematically, an unlimited range of potential values and costs that may influence left turn decisions.     

The influence of attention allocation and age on intersection accidents

Many severe accidents occur in urban areas. As part of the research project UR:BAN, this study investigated the causes of driver errors (e.g., inadequate attention allocation) in urban areas when turning left at intersections. As intersection accidents are especially difficult for older drivers, differences between older and younger drivers were examined as well. In a first step, accident protocols of left turn crashes with pedestrians and bicyclists were analysed in detail, since they are the most dangerous ones. Characteristics of the oncoming traffic and the location of crossing bicyclists and pedestrians were identified as possible causes. Accordingly, critical scenarios were implemented in a static driving simulator, varying the characteristics of the oncoming traffic, the direction and location of crossing vulnerable road users. These factors were examined in a within-subject design, with two different aged groups of participants (12 aged 20–35 y, 12 aged 65+ y; between-subjects factor).The results revealed that the presence of the oncoming traffic, which was assumed to capture the drivers’ attention, did not lead to more accidents with vulnerable road users. However, this may be because many drivers waited until the oncoming traffic had passed. Unexpectedly, older drivers had fewer accidents. This may be explained by the more cautious behaviour of older drivers, who drove significantly slower and waited significantly longer at the stop line before turning. Further analyses showed that a more cautious behaviour, independently of the age, predicted accident avoidance better than attention allocation. From these results, warning systems for younger and older drivers, especially for those not driving cautious, need to be developed. This idea will be tested in future studies introducing different warning concepts.     

Anger-congruent behaviour transfers across driving situations

Anger and aggression on the road may sometimes appear unprovoked and unrelated to current driving circumstances. It is unclear whether such anger and aggression arises because of events prior to those circumstances in which anger is experienced and aggression is exhibited. In this study, time pressure and enforced following of a slowly moving vehicle were used to increase drivers' anger in order to assess whether affect and behaviour during a subsequent, non-provocative, drive would change accordingly. Ninety-six drivers drove twice in a simulated urban environment. During the first drive, oncoming traffic and a slowly moving lead vehicle required that half of the drivers travelled far slower than they would choose. During the second drive, drivers again followed slower vehicles and were required to respond to traffic events not encountered in the manipulation drive. Mood (Profile of Mood States) was assessed before and after each drive, and anger evaluations, arousal (heart rate) and behaviour (speed, lane position and collisions) were measured during drives. Anger increased and both mood and driving behaviour deteriorated in drivers exposed to slower lead vehicles, compared with control group drivers. These behavioural differences of speed and lane positioning carried over into the subsequent drive even to driving situations unlike those where provocation had previously occurred. Drivers who had previously been impeded later approached hazards with less caution, and attempted more dangerous overtaking manoeuvres. It is concluded that sometimes dangerous driving may result from anger provoked by circumstances other than those in which the behaviour is exhibited.     

Anger-congruent behaviour transfers across driving situations

Anger and aggression on the road may sometimes appear unprovoked and unrelated to current driving circumstances. It is unclear whether such anger and aggression arises because of events prior to those circumstances in which anger is experienced and aggression is exhibited. In this study, time pressure and enforced following of a slowly moving vehicle were used to increase drivers’ anger in order to assess whether affect and behaviour during a subsequent, non-provocative, drive would change accordingly. Ninety-six drivers drove twice in a simulated urban environment. During the first drive, oncoming traffic and a slowly moving lead vehicle required that half of the drivers travelled far slower than they would choose. During the second drive, drivers again followed slower vehicles and were required to respond to traffic events not encountered in the manipulation drive. Mood (Profile of Mood States) was assessed before and after each drive, and anger evaluations, arousal (heart rate) and behaviour (speed, lane position and collisions) were measured during drives. Anger increased and both mood and driving behaviour deteriorated in drivers exposed to slower lead vehicles, compared with control group drivers. These behavioural differences of speed and lane positioning carried over into the subsequent drive even to driving situations unlike those where provocation had previously occurred. Drivers who had previously been impeded later approached hazards with less caution, and attempted more dangerous overtaking manoeuvres. It is concluded that sometimes dangerous driving may result from anger provoked by circumstances other than those in which the behaviour is exhibited.     

Examining the effect of visual treatments on truck drivers’ time-to-arrival judgments of motorcycles at T-intersections

An automobile–motorcycle crash most commonly results when an automobile pulls out of a side road into the path of an oncoming motorcycle and violates the motorcyclist’s right-of-way. One of the reasons for this could be that motorists misjudged the motorcycle arrival time. Motorcyclists are particularly vulnerable to injury in crashes with truck due to substantial differences in vehicle mass, protection degree and speed. We investigated truck drivers’ judgments of motorcycle time-to-arrival (TTA) across a number of visual treatments. Participants watched a series of video clips captured at a T-intersection, and they were instructed to respond by clicking the computer mouse at the time they estimated the front wheels of an oncoming vehicle (motorcycle or car) to reach the T-intersection. The results showed that, at long distance between the target motorcycle and the viewer, the motorcycle with daytime running headlights (DRH) was estimated to arrive sooner than the motorcycle whose motorcyclist wore a black helmet with a reflective sticker. However, the opposite is true at a short distance. We also found that a motorcyclist wearing a white helmet and riding a motorcycle with DRH, as well as a motorcyclist wearing a white helmet and white outfit, would improve truck drivers’ judgment with respect to motorcycle TTA. Consequently, truck drivers would be less likely to pull out into a small gap in front of a motorcycle, resulting in a higher safety margin for the motorcycle.     

Relative and absolute stability in perceived parenting behaviour: a longitudinal study with children and adolescents

Patterns of relative and absolute stability in parental behaviour with children and adolescents are reported. The sample comprised 523 youth (58.7% girls). Data were collected at three time periods: T1 (M age = 11.1 yr.), T2 (M age = 12.2 yr.), and T3 (M age = 13.2 yr.), each separated by one year. According to children's reports, relative consistency was moderate in both mothers and fathers, particularly as regards communication and strict control. In contrast, as children got older, parental rearing practices related to strict control and hostility decreased. There was a similarity between fathers and mothers in terms of relative and absolute stability. Relative stability was affected by the child's sex, the parenting variable, and the time period; however, the patterns of absolute stability reveal no differences by sex.     

Aging and the detection of observer and moving object collisions

The authors examined age-related differences in the detection of collision events. Older and younger observers were presented with displays simulating approaching objects that would either collide or pass by the observer. In 4 experiments, the authors found that older observers, as compared with younger observers, had less sensitivity in detecting collisions with an increase in speed, at shorter display durations, and with longer time-to-contact conditions. Older observers also had greater difficulty when the scenario simulated observer motion, suggesting that older observers have difficulty discriminating object motion expansion from background expansion from observer motion. The results of these studies support the expansion sensitivity hypothesis-that age-related decrements in detecting collision events involving moving objects are the result of a decreased sensitivity to recover expansion information.     

Drivers’ and cyclists’ safety perceptions in overtaking maneuvers

Drivers overtaking cyclists on rural roads are a safety concern, as drivers need to handle the interaction with the cyclist and possibly an oncoming vehicle. Improving the maneuver’s outcome requires an understanding of not only the objective, measurable safety metrics, but also the subjective, perceived safety of each road user. Previous research has shown that the perceived safety of the cyclist is most at risk at the passing moment, when driver and cyclist are closest to each other. However, to develop safety measures, it is necessary to know how both road users perceive safety, by understanding the factors that influence their perceptions during the overtaking maneuver. This study measured the perceived safety of drivers in a test-track experiment in Sweden and the perceived safety of cyclists in a field test in Spain. For both drivers and cyclists, we developed Bayesian ordinal logistic regression models of perceived safety scores that take as input objective safety metrics representing the different crash risks at the passing moment. Our results show that while drivers’ perceived safety decreases when there is an oncoming vehicle with a low time-to-collision, cyclists’ perceived safety is reduced by a small lateral clearance and a high overtaking speed. Although our datasets are heterogeneous and limited, our results are in line with previous research. In addition, the Bayesian models presented in this paper are novel and may be improved in future studies once more naturalistic data become available. We discuss how our models may support infrastructure development and regulation, policymaking, driver coaching, the development of active safety systems, and automated driving by providing a possible method for predicting perceived safety.     

Cohort effects in older drivers' accident type distribution: are older drivers as old as they used to be?

Accident type distributions were compared in successive cohorts of older drivers, with focus on intersection accidents. It was thought that if the increasing share of intersection accidents is a truly age-related phenomenon, as opposed to cohort-related or time-related, it would remain fairly constant over time in different cohorts. The data consisted of Finnish traffic insurance data on private car accidents of drivers aged 60 yr or more who were legally responsible for causing the accident, and covered the years 1987–1995 (N=56,481). Some changes in accident type distributions were found across cohorts. Among male drivers aged 60–79 yr, the portion of intersection accidents decreased in successive cohorts, so that the younger cohorts showed the age-typical accident picture at a somewhat later age than the older cohorts. In contrast, for male drivers aged 80 yr or more, there was an increase in the share of intersection accidents in more recent cohorts. Among female drivers, a decrease in intersection accidents only reached statistical significance for drivers aged 60–69 yr, and for the oldest age group (75+ yr) no change was observed. For both male and female drivers, the tendency to incur accidents at intersections increased with age in all cohorts. The occurrence of intersection accidents thus is both an age-related and a cohort-related phenomenon: age-related in the sense that it will emerge eventually, but with cohort-related variance in timing.     

External communication of automated vehicles in mixed traffic: Addressing the right human interaction partner in multi-agent simulation

The urban traffic system is most likely to change in the next years to a mixed traffic with human drivers, vulnerable road users, and automated vehicles. In the past, the development of external communication approaches for automated vehicles focused on scenarios where an automated vehicle communicates with either a pedestrian or a human driver. However, interactions with more than one traffic partner are more realistic. Therefore, a study with 42 participants was conducted with a multi-agent simulation in which an automated vehicle interacted simultaneously with two participants, a pedestrian and a driver of a manual vehicle. In this study, two main scenarios were investigated in order to evaluate the safety and efficiency of the interactions and to determine whether the human road users feel correctly addressed. In one scenario, the pedestrian had to cross the road in front of the automated and the manual vehicle, which were approaching from different sides. In the other, the manual vehicle had to drive through a bottleneck in front of the oncoming automated vehicle, while the pedestrian had to cross the road after both vehicles passed. The communication approach of the automated vehicle consisted of implicit signals using a speed profile and lateral offset within its lane, and explicit signals using an external human–machine interface. The results of the study show that no collisions were observed in terms of safety and no significant negative effects on efficiency were measured. However, in contrast to single agent interactions, a majority of participants felt wrongly addressed in situations where the automated vehicle signals the right-of-way to the other human road user. It can be concluded that the communication approach of the automated vehicle needs to be modified in order to address certain road users more clearly.     

Effects of driver cell-phone use on driver aggression

Using 2 field procedures, the authors assessed impacts of cell-phone use on mild forms of driver aggression. Participants were 135 drivers traveling within a city of approximately 17,000 people in an otherwise little-populated region of western North Dakota. The authors videotaped the participants while a confederate driver in a low-status vehicle frustrated them. In Experiment 1, the confederate was traveling well under the posted speed limit. In Experiment 2, the confederate remained motionless at a stoplight that had turned green. When the confederate visibly talked on a hand-held cell phone (n = 67), male drivers exhibited their frustration by honking their horn more quickly and frequently than did drivers in no-cell-phone trials, and female drivers were more angry according to blind judgments of videotaped facial expressions that were compared with those of drivers in no-cell-phone trials (n = 68). The present results suggested that driver cell-phone use contributes to the growing crisis of roadway aggression.     

Effect of motorcycle lighting configurations on drivers’ perceptions of closing during nighttime driving

ObjectiveThe aims were to better understand how drivers perceive an approaching set of motorcycle headlights during nighttime driving and to determine whether alternative motorcycle headlight configurations improve drivers’ perceptual judgments of closing for an oncoming motorcycle.BackgroundMotorcyclists account for a disproportionate number of roadway fatalities, especially at night. One potential cause of this is drivers’ misjudgments of a motorcycle’s approach.MethodThe first experiment examined whether drivers were more sensitive to horizontal or vertical optical expansion and whether drivers could integrate these two dimensions to achieve a lower looming threshold. A second experiment built on these results to test whether alternative headlight configurations that maximized size were better than other motorcycle headlight configurations and a car’s headlights. In both experiments, participants were instructed to press a button to indicate when they first perceived an oncoming vehicle to be closing under nighttime driving conditions.ResultsHeadlight orientation did not affect when drivers perceived closing, and drivers were not able to integrate optical expansion from multiple dimensions in a way that achieves a lower looming threshold. However, the alternative motorcycle headlight configurations that accentuated the full extent of a motorcycle’s size resulted in drivers perceiving closing sooner than other motorcycle headlight configurations but not sooner than a car.ConclusionDrivers perceive closing sooner for larger headlight configurations except when the headlight configurations are relatively small, in which case the effect of headlight size is attenuated.ApplicationDrivers’ perceptual judgments of motorcycles may improve when motorcycles have headlights that span its full height.     

Mild functional decline and driving performance of older drivers without a diagnosed dementia: Study of leukoaraiosis and cognitive function

Motor vehicle collisions involving older drivers have increased and become an important social issue. It is known that the decline of cognitive function, including dementia, affects driving performance. A series of studies using the Mini-Mental State Examination (MMSE) and other tests of dementia have attempted to prevent motor vehicle collisions by identifying as early as possible older drivers who may be unable to maintain their driving performance. Further, the performance of older drivers may deteriorate even if they do not have a diagnosis of dementia. Therefore we focused on the relationship between cognitive functioning assessed by the MMSE and diagnosis of leukoaraiosis (LA), or changes in the cerebral white matter, with different aspects of driving behavior resulting from aging. Qualified driving instructors evaluated participants’ driving behaviors on an outdoor driving course at a driving school. Visual search duration and angle at intersections were obtained by wearable wireless sensors. Vehicle speed and minimum vehicle speed were recorded from vehicle speed pulse signals. Duration of signaling and visual searches at unsignalized intersections were recorded using an in-vehicle camera. We assessed instructors’ evaluations and the scores on two instruments to evaluate the effects of MMSE scores and the grade of LA on driving performance were verified. The results suggest that lower MMSE scores and higher LA grade can predict some aspects of poor driving performance in older drivers before they experience dementia or an evident decline in cognitive functioning. Based on these results, we discuss countermeasures that may prevent motor vehicle collisions involving older drivers.     

Visual short-term memory, response delay, and age

Recall and recognition memory performance of 12 young (M = 19 yr.) and 12 older (M = 72 yr.) females was studied in relation to response delay (5, 25, and 125 sec.) and stimulus complexity (6.1 and 13.7 bits of information). The subjects were matched on verbal IQ, visual acuity, and educational levels. Stimuli were abstract, black and white, 4 X 4 square matrices. Age-related decrements in memory performance were associated with stimulus complexity but not with response delay. Older subjects also reported experiencing encoding difficulties during the registration phase. The results were discussed with reference to the locus of age-related decrements in visual short-term memory.     

Aging and driving in a complex world: Exploring age differences in attentional demand while driving

We investigated the relationship between attention and road complexity in a convenience sample of older drivers. The study sought to examine the impact of age-associated changes in attention in response to situations with an elevated risk of crash. Scenarios were manipulated in terms of handling and information processing complexity. Twenty-six older drivers and 30 mid-aged drivers completed a series of 20 simulated driving scenarios incorporating either rear-end or crossing path situations. For each scenario, the complexity of the driving environment was systematically manipulated in terms of vehicle handling and information processing elements. The attentional demands of half of the scenarios were assessed by means of a peripheral detection task (PDT) as well as through a subjective measure of overall difficulty. The results indicated that when information processing demands were increased, through the addition of traffic, and buildings, all participants exhibited greater workload regardless of age. While no main effects of age were observed, older drivers did exhibit significantly longer PDT responses in the low vehicle handling condition of the crossing path scenario. The results confirm the impact of environmental complexity on attention but suggest that the PDT may not be the most appropriate means of assessing attentional demands among older drivers, particularly when the driving complexity is elevated.     

The tendency of drivers to pass other vehicles

The purpose of this study was to assess the speed differential threshold—if there is one—at which drivers decide to pass a lead vehicle. Drivers in a simulator encountered vehicles in front that were programmed to travel at speeds that were similar, slightly below, or even slightly above the drivers’ own speed. The study involved a total of 152 such passing opportunities. In almost all of the encounters with slower vehicles (traveling at speeds slower than 3 km/h of the driver) they passed them, and in two thirds of the encounters when the lead vehicles were moving at their speed they passed them too. Most surprising was that in 50% of the encounters drivers passed the lead vehicle when it was traveling faster than their average speed. In these situations drivers actually increased their own speed substantially to accomplish the passing maneuver, despite the fact that not passing the lead vehicle would not have caused any delays. The tendency to pass appears to be related to the drivers’ own speed variability: the more variable the driver’s speed the more likely he or she was to pass the vehicle ahead even when its speed was greater than their average speed. The results are interpreted in terms of (a) driver aggression, and (b) association of car following with added effort, attention overload, or risk. The latter explanation implies that the tendency to pass vehicles may be reduced with the introduction of in-vehicle technologies such as adaptive cruise control.