Effects of adaptive cruise control and highly automated driving on workload and situation awareness: A review of the empirical evidence

Adaptive cruise control (ACC), a driver assistance system that controls longitudinal motion, has been introduced in consumer cars in 1995. A next milestone is highly automated driving (HAD), a system that automates both longitudinal and lateral motion. We investigated the effects of ACC and HAD on drivers’ workload and situation awareness through a meta-analysis and narrative review of simulator and on-road studies. Based on a total of 32 studies, the unweighted mean self-reported workload was 43.5% for manual driving, 38.6% for ACC driving, and 22.7% for HAD (0% = minimum, 100 = maximum on the NASA Task Load Index or Rating Scale Mental Effort). Based on 12 studies, the number of tasks completed on an in-vehicle display relative to manual driving (100%) was 112% for ACC and 261% for HAD. Drivers of a highly automated car, and to a lesser extent ACC drivers, are likely to pick up tasks that are unrelated to driving. Both ACC and HAD can result in improved situation awareness compared to manual driving if drivers are motivated or instructed to detect objects in the environment. However, if drivers are engaged in non-driving tasks, situation awareness deteriorates for ACC and HAD compared to manual driving. The results of this review are consistent with the hypothesis that, from a Human Factors perspective, HAD is markedly different from ACC driving, because the driver of a highly automated car has the possibility, for better or worse, to divert attention to secondary tasks, whereas an ACC driver still has to attend to the roadway.     

A comprehensive analysis of factors leading to speeding offenses among large-truck drivers

Much research has demonstrated that speeding is the most common offense among car drivers. However, few studies have focused on this offense among drivers of large trucks. This paper investigates the factors that lead to speeding offenses for drivers of large trucks in Taiwan. The study sample consisted of information for 2101 male large-truck drivers from a national survey in 2012. The results revealed that drivers’ daily working hours ranged from 2 to 15 h with a mean of 9.67 h, and that they worked for approximately 25.23 days – and rested only 4.77 days – per month. Among these observed drivers, 11.6% reported having at least one speeding offense over a one-year period. The results of a logistic regression model presented that the factors that influenced speeding offense were not related to job experience. Rather, the driver’s demographics (age and education), mental condition (sleep quality), and driving status (yearly distance driven and driving late at night) were significantly linked to speeding offenses.     

Timing of early warning stages in a multi stage collision warning system: Drivers’ evaluation depending on situational influences

By means of car2x communication technologies (car2x) driver warnings can be presented to drivers quite early. However, due to their early timing they could be misunderstood by drivers, distract or even disturb them. These problems arise if, at the moment of the warning, the safety–critical situation is not yet perceivable or critical. In order to examine, when drivers want to receive early warnings as a function of the situation criticality, a driving simulator study was conducted using the two early warning stages of a multi stage collision warning system (first stage: informing the driver; second stage: prewarning the driver). The optimum timing to activate these two early warning stages was derived by examining the drivers’ evaluation of these timings concerning their appropriateness and usefulness. As situational variation, drivers traveling at about 100 km/h were confronted with slow moving traffic either driving at 25 km/h or 50 km/h at the end of a rural road.In total, 24 participants were tested in a within-subjects design (12 female, 12 male; M = 26.6 years, SD = 7.2 years). For both stages, drivers preferred an earlier timing when approaching slow moving traffic traveling at 25 km/h (first stage: 447 m, second stage: 249 m ahead of the lead vehicle) compared to 50 km/h (first stage: 338 m, second stage: 186 m ahead of the lead vehicle). The drivers’ usefulness rating also varied with the timing, spanning a range of 8 s for driver-accepted timing variations and showed correspondence to the drivers’ appropriateness ratings. Based on these results and those of a previous study, a timing function for each of the two early warning stages depending on the speed difference between the safety–critical object and the host vehicle is presented. Indirectly, similar adaptations are already implemented in current collision warning systems, which use the time-to-collision to give drivers acute warnings in a later stage, when an immediate reaction of the driver may still prevent a collision. However, this study showed that drivers also favor this kind of adaptation for earlier warning stages (information and prewarning). Thus, adapting the timing according to the drivers’ preferences will contribute to a better acceptance of these collision warning systems.     

Everyday dynamics in generalized social and political trust

We applied the traits as density distributions of states approach to generalized expectations of trustworthiness, namely, social trust and trust in politicians. Using an experience sampling study (N = 47), we assessed state social trust and trust in politicians four times a day for 2 weeks. Within-person variability was found to be low but meaningful as it was predicted by variations in affect, interactional trust, and prior experiences. There was high stability in interindividual differences in the mean levels of state trustworthiness expectations and in the levels of within-person variability. Our study provides a comprehensive understanding of stability and variability in generalized expectations of trustworthiness and indicates broad applicability of the traits as density distributions of states approach.     

Controllability of Partially Automated Driving functions – Does it matter whether drivers are allowed to take their hands off the steering wheel?

Different motor vehicle manufacturers have recently introduced assistance systems that are capable of both longitudinal and lateral vehicle control, while the driver still has to be able to take over the vehicle control at all times (so-called Partial Automation). While these systems usually allow hands-free driving only for short time periods (e.g., 10 s), there has been little research whether allowing longer time periods of hands-off driving actually has a negative impact on driving safety in situations that the automation cannot handle alone. Altogether, two partially automated assistance systems, differing in the permitted hands-off intervals (Hands-off system vs. Hands-on system, n = 20 participants per assistance condition, age 25–70 years) were implemented in the driving simulation with a realistic take-over concept. The Hands-off system is defined by having a permitted hands-off interval of 120 s, while the Hands-on system is defined by a permitted hands-off interval of 10 s. Drivers’ reactions at a functional system limit were tested under conditions of high ecological validity: while driving in a traffic jam, participants unexpectedly encountered a time-critical situation, consisting of a vehicle at standstill that appeared suddenly and required immediate action. A visual-auditory take-over request was issued to the drivers. Regardless of the hands-off interval, all participants brought the vehicle to a safe stop. In spite of a stronger brake reaction with the Hands-on system, no significant differences between assistance levels were found in brake reaction times and the criticality of the situation. The reason for this may be that most of the drivers kept contact with the steering wheel, even in the Hands-off condition. Neither age nor prior experience with ACC was found to impact the results. The study thus demonstrates that permitting longer periods of hands-off driving does not necessarily lead to performance deficits of the driver in the case of take-over situations, if a comprehensive take-over concept is implemented.     

Belief in a just world mediates the relationship between institutional trust and life satisfaction among the elderly in China

This study investigated the relationship between institutional trust and life satisfaction, and the mediating role of belief in a just world (BJW) among the elderly. The General Belief in a Just World Scale (GBJW) and Satisfaction with Life Scale (SWLS) were employed. A self-developed Institutional Trust questionnaire was used to measure participant’ levels of trust in eight institutions. The aggregate score for all eight items represented the level of institutional trust. The questionnaires were completed by 19,352 retirees ranging in age from 50 to 99 (M = 69.7, SD = 8.0). The results showed the following: (1) overall, the retirees tended to report high institutional trust and high life satisfaction; (2) institutional trust was positively associated with life satisfaction; and (3) more importantly, the relationships between institutional trust and life satisfaction were partially mediated by GBJW. This finding provides a new insight into the psychological mechanisms by which institutional trust relates to individual happiness. The theoretical and practical implications of these findings, as well as the study’s limitations, are discussed.     

L’évolution des facteurs prédictifs de la détresse psychologique des étudiants en contexte de Covid-19 : un modèle d’équation structurelle exploratoire

IntroductionStudents are at risk for mental health issues due to the COVID-19 pandemic. The implementation of lockdowns as a means to curb the spread of the disease have had an impact on this population, as observed in many international studies. However, few studies have investigated the longitudinal impact of COVID-19 lockdowns on students’ mental health.ObjectiveWe explored the relation between individual characteristics of students, context of life, difficulties in emotion regulation and psychological distress over the first two lockdowns in France during the COVID-19 pandemic.Methodology160 university students (90% female, mean of 24 years old) responded to an online questionnaire at three times points: once during the first lockdown during the COVID-19 pandemic in march 2020, a second time after this lockdown and a third time during the second lockdown. Difficulties in emotion regulation, psychological distress, acute stress, academic concerns, financial resources, and exchanges with professors were measured.ResultsAn exploratory structural equations model was developed to investigate the factors related to psychological distress (χ² = 1459.18, df = 1064, CFI = 0.910, RMSEA = 0.049, SRMR = 0.068). During both lockdowns, psychological distress was explained by academic concerns and lack of emotional clarity and acceptance. An indirect and negative significant relation was identified between financial difficulties, lack of exchanges with professors during the first lockdown, emotion clarity and experienced psychological distress during the second lockdown. Repeated measures ANOVAs identified high levels of acute stress during both lockdowns and a diminution during the deconfinement indicating an impact of sanitary measures on student's mental health.ConclusionCoherently with the Bruchon-Sweiser translational model of stress, emotion regulation capacities seem to have a central and moderating role in the experience of the pandemic for students. They would benefit greatly from appropriate therapeutic interventions in this pandemic situation and in general.     

Gap acceptance at stop-controlled T-intersections in a simulated rural environment

A high proportion of road crashes occur at intersections: in Victoria, Australia, 15% of fatal crashes and 25% of serious injury crashes occur at T-intersections, with similar proportions occurring at cross intersections. Many of these crashes can be attributed to drivers’ inappropriate gap selection. The current study used a driving simulator to examine the influence of both the driver’s intended manoeuvre and the gap duration on gap acceptance behaviour at stop-controlled T-intersections. Drivers completed 18 gap acceptance trials, with manoeuvre (turning across traffic, merging with traffic) and gap duration (3–11 s) manipulated within-subjects. There was a trend whereby drivers accepted shorter gaps when turning across traffic compared to merging with traffic, which was significant at longer gaps (⩾9 s) but not at shorter, safety–critical gaps (⩽8 s). In addition, accepted lag times varied with manoeuvre. When merging with traffic drivers demonstrated longer accepted lag times, suggesting that turn strategies differ depending on traffic direction and intended manoeuvre. Overall the results suggest that the drivers’ intended manoeuvre influences gap acceptance, although gap duration remains the most influential factor. Implications of these findings for the development and design of intersection decision support systems are discussed.     

Reward versus punishment: Reinforcement sensitivity theory,young novice drivers’ perceived risk,and risky driving

One reason that young novice drivers remain statistically over-represented in road deaths is their rate of engagement in risky driving. Prominent contributing factors include driver’s age, sex, personality, risk perception, and their driving experience. This study applied reinforcement sensitivity theory (RST, specifically reward sensitivity and punishment sensitivity) to predict young novice drivers’ perceived risk and self-reported risky driving engagement, while accounting for potential influences of age, sex, and driving experience. Drivers (N = 643, 490 females, 17–25 years, M = 20.02, SD = 2.32) who held an Australian driver’s license (P1, P2, or Open) anonymously completed an online survey containing the Behaviour of Young Novice Drivers Scale, the Sensitivity to Punishment and Sensitivity to Reward Questionnaire, and a measure of perceived risk of driving-related behaviours. A path analytic model derived from RST showed that perceived risk had the strongest negative association with reported risky driving engagement, followed by reward sensitivity (positive association). Respondent’s age and reward sensitivity were associated with perceived risk. Age, reward sensitivity, and perceived risk were associated with reported engagement in risky driving behaviours. Driver sex only had direct paths with RST variables, and through reward sensitivity, indirect paths to perceived risk, and reported risky driving. Neither punishment sensitivity nor driving experience contributed significantly to the model. Implications and applications of the model, and the unique set of variables examined, are discussed in relation to road safety interventions and driver training.     

Concept evaluation of intersection decision support (IDS) system interfaces to support drivers’ gap acceptance decisions at rural stop-controlled intersections

Rural stop-controlled intersections pose a crash risk for drivers turning or crossing the intersection from the minor road. In particular, elderly drivers are at the highest risk of a collision in this situation. Errors made during gap detection, perception and acceptance are the main factors that influence crashes at this type of intersection. This study investigated young (20–40 years) and old (55–75 years) drivers’ gap acceptance performance in simulated day and night driving conditions in a Baseline condition (STOP sign only) and four intersection decision support (IDS) conditions. The four IDS conditions were initial infrastructure-based design concepts that provided varying levels of dynamic information about traffic conditions on the major road to crossing minor-road drivers. Signs that provided detailed gap information (i.e., time-to-arrival values, warning levels for gaps) as well as advisory information about unsafe conditions resulted in the best performance among old and young drivers in comparison to signs that did not provide specific gap-related information (i.e., detected vehicles approaching, but not size of gap or safety of gap). Comprehension, acceptance and usability ratings of the IDS signs were also highest for signs providing detailed gap and advisory information on the same sign. Recommendations for further design and development of the IDS system interface based on driver performance and acceptance of the technology is discussed.     

Antecedent variables of intentions to use an autonomous shuttle: Moving beyond TAM and TPB?

IntroductionThe use of autonomous shuttles (AS) seems a promising mobility solution. Technology acceptance model (TAM) and theory of planned behavior (TPB) provide useful a priori frameworks to study AS’ acceptance, but they might arguably benefit from a specific, AS-related adjustment.ObjectiveTo provide a preliminary model of AS’ acceptance based on both laboratory and field data.MethodUndergraduate students (n = 370, study 1) and both the potential and the real AS users (n = 162, study 2) answered surveys concerned with the key TAM, TPB and evidence-based additional variables.ResultsSome of TAM and TPB constructs accounted for 40% of intentions to use an AS while further 13 to 16% were explained systematically by such variables as group norms, affective attitudes and first AS experience.ConclusionSome of TAM and TPB constructs capture substantial proportion of AS’ acceptance while additional social, motivational and experience-related factors should be taken into account.     

Contextual Design for driving: Developing a trip-planning tool for older adults

Independent living depends on mobility, and mobility depends on driving, particularly for people 65 years and older. The longer older adults can safely drive, the longer they can independently run errands, shop, exercise, and maintain social networks. Age-related decline of perceptual, motor, and cognitive abilities can undermine the mobility and driving safety of older drivers. Data from driving simulators, on-road tests, surveys, and crash reports describe the driving safety and mobility challenges of older adults, but these methods offer a limited view of these challenges and fail to indicate design solutions. Contextual Design—a combination of Contextual Inquiry interviews, model building, and affinity diagrams—offers a complementary approach to uncover challenges that older adult drivers’ experience. For two weeks, 39 drivers age 65 and above, had their vehicles instrumented to collect driving and video data. Applying Contextual Design to these data showed that older drivers in urban and rural settings faced different mobility challenges and adopted various strategies to mitigate risk: older drivers often involved their spouse or passenger in the driving task, avoided certain driving maneuvers such as left turns, avoided unfamiliar or poorly lit roads at night, and planned trips to avoid risky driving situations. Ridesharing and trip planning emerged as important strategies to improve the safety and mobility of older drivers. Ridesharing could serve as a potential solution to prolong mobility; however, factors such as wait time, scheduling conflicts, costs, and trust were concerns for older drivers. A paper prototype was developed to validate the driving challenges faced by older drivers, and guide the development of a customized web-based trip-planning tool. The trip-planning tool could help older drivers make safer route choices by offering routes with fewer driving challenges, thereby enhancing their driving safety, mobility, and independence.     

The factors of female taxi drivers’ speeding offenses in Taiwan

Females choosing taxi driving as a career is rare, therefore, investigating such samples is often difficult. Speeding is one of the most common driving violations, however, there has been no research looking into female taxi drivers’ speeding issue. This study explores the factors of female taxi drivers’ speeding offenses in Taiwan. Data is based on a national survey and includes 235 professional female taxi drivers. The results indicate that female taxi drivers work approximately 27.37 days per month, at a mean of 9.76 h per day. Of the female taxi drivers represented in this study, 22.8% reported at least one speeding offense over a one-year period. The results of a logistic regression model reveal that the determinant factors associated with female taxi drivers’ speeding offenses are significantly related to age, educational level and mileage driven. However, job experience, business operating style, and vehicle engine size are not associated with committing speeding offenses. Practical implications for traffic safety of female taxi drivers are also discussed.     

Measurement and comparative analysis of driver’s perception–reaction time to green phase at the intersections with and without a countdown timer

This paper proposes a method based on digital image processing for measuring drivers’ perception–reaction time (PRT) to the green phase. The detection of the onset of a green signal was based on the RGB color model. The detection of the start of the vehicle was based on the frame difference. The driver’s perception–reaction time was equal to the difference between the frame of the onset of the green signal and the frame of the start of the vehicle divided by the video frame rate. Drivers’ PRT with and without a countdown timer were comparatively analyzed. First, the means and variances of drivers’ PRT with a timer and without a timer were compared. Second, Normal, Lognormal, Gamma and Weibull distributions were used to fit the PRT data. Third, the fuzzy c-means clustering was utilized for PRT classification and comparison. The results show that the method for measuring drivers’ PRT based on digital image processing was effective. The drivers’ PRT was decreased from 2.12 s to 1.48 s with countdown signals. Weibull distribution appeared to best fit the PRT with No-Timer and Lognormal distribution appeared to best fit the PRT with Timer. The PRT data were classified into three groups: “Fast”, “Moderate” and “Slow”. Clustering centers without Timer were 1.16 s, 2.47 s and 3.98 s respectively. Clustering centers with Timer were 0.95 s, 1.64 s and 2.70 s respectively. The clustering centers can be regarded as reference values of drivers’ starting response for microscopic traffic simulation software.     

A randomized controlled trial of strong minds: A school-based mental health program combining acceptance and commitment therapy and positive psychology

To date, most early intervention programs have been based on emotion regulation strategies that address dysfunctional cognitive appraisals, problem-solving skills, and rumination. Another emotion regulation strategy, ‘acceptance’ training, has largely been overlooked. To examine the efficacy of this strategy, a school-based mental health program combining positive psychology with acceptance and commitment therapy (Strong Minds) was evaluated in a randomized controlled trial with a sample of 267 Year 10 and 11 high-school students in Sydney, Australia. Mixed models for repeated measures examined whether the program led to reductions in symptoms amongst students who commenced the program with high depression, anxiety, and stress scores, and increased wellbeing scores amongst all students. Results demonstrated that compared to controls, participants in the Strong Minds condition with elevated symptom scores (n = 63) reported significant reductions in depression (p = .047), stress (p = .01), and composite depression/anxiety symptoms (p = .02) with medium to strong effect sizes (Cohen's d = 0.53, 0.74, and 0.57, respectively). Increased wellbeing (p = .03) in the total sample and decreased anxiety scores (p = .048) for students with elevated symptoms were significant for Year 10 students with medium effect sizes (Cohen's d = 0.43 and 0.54, respectively). This study tentatively suggests that including the emotion regulation strategy of acceptance in early intervention programs may be effective in reducing symptoms and improving wellbeing in high school students. Further research to investigate the generalizability of these findings is warranted.     

The relationship between mental toughness and affect intensity

Mentally tough athletes are conceptualized as being able to function effectively in stressful situations and recent research has found small to moderate correlations between mental toughness and coping. Despite this no research has thus far examined the possibility that mentally tough athletes experience less intense emotions. This paper tested the relationship between mental toughness and affect intensity to determine whether mentally tough athletes generally experienced more or less intense emotions. A sample of 112 sport performers (55 men and 57 women) aged between 18 and 51 years (M = 29.3, s = 10.3) acted as participants, and ranged from recreational to national level in a variety of sports. Mental toughness and affect intensity were found to be unrelated. This is an important finding because it suggests participants with high or low levels of mental toughness do not characteristically experience more or less intense emotions. Thus there is no evidence to suggest the ability of mentally tough athletes to remain relatively unaffected by pressure or adversity is due to lower levels of affect intensity. More research is required to understand how mentally tough athletes (in comparison to less tough athletes) maintain control and high levels of performance in stressful circumstances.     

Risk comparative judgments while driving a car among competitive road cyclists and non-cyclists

This study examines risk comparative judgments and risky behaviors while driving a car among competitive road cyclists (n = 119) and among controls (i.e., drivers who have almost no cycling experience, n = 142). A questionnaire-based cross-sectional survey was conducted. Results showed that competitive road cyclists assess their own vulnerability to be involved in an accident while riding (VAR) as being lower than that of the average cyclists, and their abilities to manage risks while riding (AMRR) as being higher. They assessed their own vulnerability to be involved in an accident while driving a car (VAD) as being lower than that of the average drivers, and their own quality of reflexes while driving a car (QRD) as being higher. Their tendency to express comparative optimism while assessing their comparative VAD and QRD was higher than that of controls. They also reported more prudent behaviors while driving a car than did controls. Results are discussed, as well as implications in terms of prevention.     

The effects of dimmable road lighting: A comparison of measured and perceived visibility

By dimming road lighting, energy can be conserved without compromising traffic safety. This paper presents a study carried out on the effect of different lighting levels from road luminaires on drivers’ visual performance on a low traffic urban road. The small uniform target was used to evaluate the visibility performance of the drivers. The results obtained from subjective graded visibility were compared with contrast and the Adrian model. Results indicated a strong correlation between subjective graded visibility and contrast (R² = 0.94) and a positive correlation between subjective graded visibility and the Adrian model (R² = 0.88). Target’s location in relation to road luminaires had a considerable effect on its visibility. However, visibility is not a monotonic function of road lighting level. In the absence of glare from an oncoming car, 49% (3557 lm) of road lighting intensity provided better contrast and mean visibility than 100% (7252 lm) and 71% (5179 lm) of road lighting intensities. The glare from oncoming cars reduced visibility. However, no statistically significant effect of road lighting level on visibility under glare could be found.     

Effects of distraction and experience on situation awareness and simulated driving

This study examined the impact of cell phone conversation on situation awareness and performance of novice and experienced drivers. Driving performance and situation awareness among novice drivers ages 14–16 (n = 25) and experienced drivers ages 21–52 (n = 26) were assessed using a driving simulator. Performance was measured by the number of driving infractions committed: speeding, collisions, pedestrians struck, stop signs missed, and centerline and road edge crossings. Situation awareness was assessed through a query method and through participants’ performance on a direction-following task. Cognitive distractions were induced through simulated hands-free cell phone conversations. The results indicated that novice drivers committed more driving infractions and were less situationally aware than their experienced counterparts. However, the two groups suffered similar decrements in performance during the cell phone condition. This study provides evidence of the detrimental effects of cell phone use for both novice and experienced drivers. These findings have implications for supporting driving legislation that limits the use of cell phones (including hands-free) in motor vehicles, regardless of the driver’s experience level.