Human factors of transitions in automated driving: A general framework and literature survey

The topic of transitions in automated driving is becoming important now that cars are automated to ever greater extents. This paper proposes a theoretical framework to support and align human factors research on transitions in automated driving. Driving states are defined based on the allocation of primary driving tasks (i.e., lateral control, longitudinal control, and monitoring) between the driver and the automation. A transition in automated driving is defined as the process during which the human-automation system changes from one driving state to another, with transitions of monitoring activity and transitions of control being among the possibilities. Based on ‘Is the transition required?’, ‘Who initiates the transition?’, and ‘Who is in control after the transition?’, we define six types of control transitions between the driver and automation: (1) Optional Driver-Initiated Driver-in-Control, (2) Mandatory Driver-Initiated Driver-in-Control, (3) Optional Driver-Initiated Automation-in-Control, (4) Mandatory Driver-Initiated Automation-in-Control, (5) Automation-Initiated Driver-in-Control, and (6) Automation-Initiated Automation-in-Control. Use cases per transition type are introduced. Finally, we interpret previous experimental studies on transitions using our framework and identify areas for future research. We conclude that our framework of driving states and transitions is an important complement to the levels of automation proposed by transportation agencies, because it describes what the driver and automation are doing, rather than should be doing, at a moment of time.     

The effect of fatigue driving on car following behavior

Existing fatigued driving analysis methods mainly focus on lateral driving performance by using the measurements related to the steering wheel or lane position. There is a lack of research on longitudinal car following behavior. In this study, 40 professional drivers are invited to participate in field expressway driving experiment, lasting at least for 6 h. During the test, their performance is measured in terms of their self-reported fatigued driving level according to the Karolinska Sleepiness Scale (KSS), the PERcentage of eye CLOSures (PERCLOS) and the Time Headway (THW). Then the effects of the fatigued driving level on car following behavior are evaluated. The results indicate that the fatigue level (for both KSS and PERCLOS) has significantly impact on THW parameters, including the mean, standard deviation and minimum THW. An increase in KSS and PERCLOS leads to a lower mean and minimum THW. Meanwhile, the standard deviation of THW increases with the increase of KSS and PERCLOS. In conclusion, this study found that a higher fatigue level leads to the driver keeping a smaller THW when following another vehicle and choosing shorter THW to make lane change. More deviation of car following performance was also found with the increase of fatigue level. Therefore, the findings of this study can be used to explain fatigue as one of the major reasons for rear-end collisions. Also, the research findings demonstrate the impact of fatigue on driving behavior in terms of car following performance, which can be used as a measurement for monitoring fatigued drivers.     

Characteristics of college students who text while driving: Do their perceptions of a significant other influence their decisions?

IntroductionTexting while driving is a significant risk factor for automobile collisions. The use of cell phones is prevalent among young people and commonly reported when they drive.MethodA web-based survey of 861 college student drivers determined how texting was associated with other forms of risky driving, perceptions of risk, and their driving and texting interactions with a significant other.ResultsTexting drivers were more likely to engage in other risky driving behaviors, perceived less risk in texting and driving, felt more immune to traffic risks, and had friends who text and drive. Logistic regression analyses showed that even after adjusting for risky driving behaviors and perceived risk, texting drivers were significantly more likely to do so if they saw their significant other text and drive.ConclusionsTraffic safety campaigns need to address important social influences on this behavior.     

An investigation of behaviour and attitudes relevant to the user safety of pedestrian/cyclist shared paths

Bicycle/pedestrian shared paths are an increasingly popular solution to providing cycling infrastructure, despite evidence suggesting safety issues. Improved design and management of shared paths should be informed by understanding of bicyclist and pedestrian behaviour on shared paths, and of relevant safety initiatives (e.g. centreline marking). However, relevant research is lacking. Bicyclist/pedestrian passing events (n = 407) were observed on three relatively busy shared paths in Sydney, Australia – one of them without centreline marking. User characteristics, relevant behaviours and incidents (aggression, near-misses, crashes) were recorded. A tendency toward left-hand travel, as on Australian roads, was stronger for cyclists than for pedestrians, and where centreline was present. Cyclists were often estimated to travel above 10 km/h, a speed limit that has been suggested based on pedestrian safety considerations, but that would be unacceptable for long stretches of commuter cycling. Centreline was associated with lower estimated speeds. Cyclists typically adhered to their responsibility of giving way to pedestrians, but often passed on the left, passed too close, passed without slowing, or passed without warning (e.g. with a bell). Use of mobile telephones and mp3 players is common, particularly amongst pedestrians. Five near collisions were observed, and 53 survey participants reported 2 collisions and 13 near misses. Contributing factors appear to include path users using potentially distracting devices, or straying from the rules of thumb to keep to the left, and to overtake on the right.A survey of cyclists and pedestrians suggested that there are issues with perceptions of space ownership. These results represent an important contribution to the evidence-base for initiatives to improve the safety of shared paths.     

Does avoidance‐attachment style attenuate the benefits of being listened to?

We tested both Rogers's hypothesis that listening enables speakers to experience psychological safety and our hypothesis that the benefit of listening for psychological safety is attenuated by avoidance‐attachment style. We tested these hypotheses in six laboratory experiments, a field correlational study, and a scenario experiment. We meta‐analyzed the results of the laboratory experiments and found that listening increased psychological safety on average but that the variance between the experiments was also significant. The between experiment variance in the effect of listening manipulation on psychological safety exposes a methodological challenge in choosing a research paradigm of good‐versus‐normal listening, as opposed to normal‐versus‐poor listening. More importantly, we found, as expected and across all designs, that the higher the avoidance‐attachment style was, the lower the effect of listening on psychological safety. This finding has implications both for practice and for placing a theoretical boundary on Rogers's theory.     

Traffic congestion,driver stress,and driver aggression

Drivers were interviewed over cellular telephones in high‐ and low‐congestion conditions during a single commute. During each interview, state measures of driver stress and driver behaviors were obtained. Behavior responses were subdivided into six categories: aggressive, information seeking, planning, minor self‐destructive, distraction, and relaxation techniques. Both state driver stress and aggression were greater in high‐ than in low‐congestion conditions. No other behavior category differed between low and high congestion. Multiple regressions were calculated to determine the predictors of state driver stress. In low congestion, time urgency predicted state driver stress, while aggression predicted driver stress in high congestion. In both conditions, a trait susceptibility toward viewing driving as generally stressful was predictive of state driver stress levels, which further strengthens the use of the Driving Behaviour Inventory—General as a predictor of “trait” driver stress. Females and males did not differentiate on state stress or any behavior category. Aggr. Behav. 25:409–423, 1999. © 1999 Wiley‐Liss, Inc.     

Do older individuals have difficulty processing motion or excluding noise? Implications for safe driving

This study aimed to determine if difficulties extracting signal from noise explained poorer coherent motion thresholds in older individuals, particularly women. In four experimental conditions the contrast of the signal and noise dots used in a random dot kinematogram was manipulated. Coherence thresholds were highest when the signal dots were of a lower contrast than the noise dots and lowest when the signal dots were of a higher contrast than the noise dots. In all conditions the older group had higher coherence thresholds than the younger group, and women had higher thresholds than men. Significant correlations were found between coherence thresholds and self-reported driving difficulties in conditions in which the signal dots had to be extracted from noise only. The results indicate that older individuals have difficulties extracting signal from noise in cluttered visual environments. The implications for safe driving are discussed.     

Effect of multimodal takeover request issued through A-pillar LED light,earcon, speech message,and haptic seat in conditionally automated driving

The driver of a conditionally automated vehicle equivalent to level 3 of the SAE is obligated to accept a takeover request (TOR) issued by the vehicle. Considerable research has been conducted on the TOR, especially in terms of the effectiveness of multimodal methods. Therefore, in this study, the effectiveness of various multimodalities was compared and analyzed. Thirty-six volunteers were recruited to compare the effects of the multimodalities, and vehicle and physiological data were obtained using a driving simulator. Eight combinations of TOR warnings, including those implemented through LED lights on the A-pillar, earcon, speech message, or vibrations in the back support and seat pan, were analyzed to clarify the corresponding effects. When the LED lights were implemented on the A-pillar, the driver reaction was faster (p = 0.022) and steering deviation was larger (p = 0.024) than those in the case in which no LED lights were implemented. The speech message resulted in a larger steering deviation than that in the case of the earcon (p = 0.044). When vibrations were provided through the haptic seat, the reaction time (p < 0.001) was faster, and the steering deviation (p = 0.001) was larger in the presence of vibrations in the haptic seat than no vibration. An interaction effect was noted between the visual and auditory modalities; notably, the earcon resulted in a small steering deviation and skin conductance response amplitude (SCR amplitude) when implemented with LED lights on the A-pillar, whereas the speech message led to a small steering deviation and SCR amplitude without the LED lights. In the design of a multimodal warning to be used to issue a TOR, the effects of each individual modality and corresponding interaction effects must be considered. These effects must be evaluated through application to various takeover situations.     

安全动机在安全绩效模型中的作用：自我决定理论的视角

在日常工作中, 安全动机是员工保持安全行为的重要决定因素。安全动机对安全绩效的影响虽然已引起研究者的关注, 但相关的实证研究缺少清晰的理论界定和有效的测量工具。本项目拟在安全绩效模型的基础上, 借鉴自我决定理论对动机的分类, 将安全动机的类型进行扩展, 并在多层次模型中探讨安全动机在变革型领导、个体特征和安全绩效之间的中介作用, 以及在中国管理背景下可能存在的边界条件。研究将结合访谈、问卷和情境实验等方法对上述变量间关系进行相关和因果关系的探讨。本项目将自我决定理论与安全绩效模型相结合, 可以为安全研究的动机理论发展做出贡献; 研究结果亦可为安全管理实践提供评价工具和有效指导。     

INCREASING SEAT BELT USE ON A COLLEGE CAMPUS: AN EVALUATION OF TWO PROMPTING PROCEDURES

Seat belt use is an important factor in the prevention of automobile accidents involving injuries and fatalities. The current study used a multielement design to compare the “Click It or Ticket” and “Please Buckle Up—I Care” procedures. Results indicate that the Click It or Ticket prompt resulted in a 20‐percentage‐point increase in seat belt use, and Please Buckle Up—I Care resulted in a 14‐percentage‐point increase.