Driver hand position on the steering wheel while merging into motorway traffic

It has been suggested that a driver’s hand position on the steering wheel can reflect the perceived risk of the road context (Walton, D., & Thomas, J. A. (2005). Naturalistic observations of driver hand positions. Transportation Research Part F, 8, 229–238, Thomas, J. A., & Walton, D. (2007). Measuring perceived risk: Self-reported and actual hand positions of SUV and car drivers. Transportation Research Part F, 10, 201–207). These original studies were based on field observations where only a part of the steering wheel could be viewed. In the present study hand positions were observed in a driving simulator during the performance of a demanding task; merging into motorway traffic. In the current study the whole steering wheel could be observed and hand positions were classified in three categories: high control, medium control, and low control. Differences in hand position between different traffic conditions were limited, and hand position did not correlate with self-reported risk or self-reported mental effort, but changes in hand positions do seem to be associated with changes in workload demand. It is therefore concluded that hand position can give some information about mental workload.     

Naturalistic observation of drivers’ hands, speed and headway

Drivers’ hands position have been shown to vary with traffic speed and complexity of the driving environment, such that drivers are more likely to place two hands on the top half of the steering wheel as the supposed driving difficulty increases (Walton, D. & Thomas, J. A. [2005]. Naturalistic observations of driver hand positions. Transportation Research Part F, 8, 229–238). This research evaluates drivers’ hands positions, examining the reliability of the measure and the relationship between the positions of the driver’s hands, vehicle speed, vehicle headway and driver sex. The findings show that the observed positions of drivers’ hands have good inter-rater reliability and demonstrate both temporal and contextual reliability. The positions of drivers’ hands are related to other measures, such that drivers with lower-ranked positions of hands are more likely to travel at higher speeds and accept shorter headways. Female drivers are found to be 2.87 times more likely than males to place two hands rather than one hand on the top half of the steering wheel.     

Measuring perceived risk: Self-reported and actual hand positions of SUV and car drivers

This research examines the observed steering wheel hand positions and the reported steering wheel hand placements of a sample of Sports Utility Vehicle (SUV) and car drivers. Following the method of Walton and Thomas (Walton, D. & Thomas, J. A. (2005). Naturalistic observations of driver hand positions. Transportation Research Part F. Traffic Psychology and Behaviour, 8, 229–238), variation in hand position is found to be an effective, indirect measure of drivers’ perceived risk. As perceived risk increases, it is expected that drivers will be more likely to adopt a ‘10–2 o’clock’ hand placement to increase their control over the vehicle. Because they are a larger vehicle, SUVs are typically perceived by drivers as being safe, so it is also expected that SUV drivers would have a lower level of perceived risk, as evidenced by their hand positions. A questionnaire examining drivers’ hand placements confirmed that drivers do perceive that two hands on the top half of the steering wheel will give the most control over the vehicle, and also revealed that drivers overestimate their use of this hand position, when compared with actual observation. Observed hand positions reveal that SUV drivers are more likely to drive with one hand instead of two hands on the top half of the steering wheel, indicating a lower level of perceived risk.     

A comparison of experienced and novice drivers’ rear-end collision avoidance maneuvers under urgent decelerating events

A leading vehicle’s sudden deceleration can lead to a rear-end collision. Due to a lack of driving experience, novice drivers have a greater tendency to be involved in these accidents. Most previous studies have examined driver response time and braking behaviors, but few researchers have focused on what experienced and novice drivers did after their feet touched the braking pedal and their hands turned the steering wheel. These braking and steering parameters are essential in understanding driver avoidance behavior during emergencies. We programmed rear-end crash risk scenarios to examine experienced and novice drivers’ behaviors thoroughly using a driving simulator. Twenty experienced and twenty five novice subjects participated in our experiments, and their braking and steering maneuvers were recorded when leading vehicles ran at 60 km/h, 80 km/h and 100 km/h. The results showed that the two groups of subjects tended to execute two kinds of maneuvers to avoid crashes: braking only (novice 33%, experienced 19%) and the combination of braking with steering (novice 22%, experienced 26%). When the novice drivers executed braking with steering, their response time and steering duration were significantly longer than those of the experienced drivers who executed braking with steering. As the speed increased, the novice drivers’ response time, maximum braking force and maximum steering angle were significantly affected. These results showed that novice drivers should brake only when the leading vehicle suddenly decelerates. The experienced drivers executed steadier maneuvers. Their risk perception time was shorter, and their maximum braking force and the maximum steering angles were smaller. The response time, braking intensity and steering wheel angle should be considered when developing rear-end collision warning systems.     

A performance analysis of In-Car Music engagement as an indication of driver distraction and risk

Drivers engage in a host of driving-unrelated tasks while on the road. They listen to music, sing-along, and accompany songs by pounding-out drum-kicks and syncopated rhythms on the steering wheel. However, there is controversy over in-cabin music: Does background music facilitate driver performance via increased arousal leading to more focused concentration, or cause distraction placing drivers at greater risk. In an effort to shed light on the debate, the current study evaluated music engagement by employing Music Performance Analyses with audio recordings from three simulated driving conditions. The results indicate that as the perceptual demands of the primary driving task increased, the secondary music activity was hampered, and subsequently sub-optimal vocal and percussive performances were demonstrated consisting of intonation errors, rhythmic inaccuracy, lack of synchrony, inconsistent and unstable temporal flow, neglect of text, and lyric replacement. The findings seem to point out that drivers allocate greater reserves to music than previously considered, and as drivers do not withdraw altogether from music engagement under high-demand driving conditions, driving may be under-resourced. Exploring active music engagement while driving might assist traffic safety researchers in decoding the effects of In-Car Music on driver behavior.     

Psychological characteristics of aggressive drivers with and without intermittent explosive disorder

We compared two groups of aggressive drivers, those who met criteria for Intermittent Explosive Disorder (IED) (n=10) and comparable aggressive drivers who did not meet IED criteria (n=20), to a group of non-aggressive driving controls (n=20) on measures of psychological distress, anger, hostility, and Type A behavior as well as measures of aggressive driving and driving anger and their driving records. There were few differences between the aggressive drivers with IED and those without IED. The IED positive aggressive drivers endorsed more assaultiveness and resentment as well as more impatience and showed trends to have more hostility and angry temperament. When all aggressive drivers were compared to controls, differences emerged on anxiety, hostility, and anger as well as on measure specific to aggressive driving (competitiveness) and driving anger (at slow drivers and traffic obstructions).     

危险类型对公交驾驶员危险知觉的影响

结合反应时方法和多维度驾驶风格量表,以140名公交驾驶员为研究对象,采用2（危险类型：隐藏危险、明显危险）×2（驾驶员分组：有无交通违规/事故记录）的混合实验设计考察危险类型对危险知觉的影响。结果发现：驾驶员对明显危险的反应时比隐藏危险短,无交通违规/事故记录驾驶员对明显和隐藏危险的反应时均比有交通违规/事故记录驾驶员短。控制驾驶风格后,危险类型主效应不再显著。结果表明,公交驾驶员危险知觉的特点随着危险类型不同而变化。     

Effects of visual and cognitive load in real and simulated motorway driving

As part of the HASTE European Project, effects of visual and cognitive demand on driving performance and driver state were systematically investigated by means of artificial, or surrogate, In-vehicle Information Systems (S-IVIS). The present paper reports results from simulated and real motorway driving. Data were collected in a fixed base simulator, a moving base simulator and an instrumented vehicle driven in real traffic. The data collected included speed, lane keeping performance, steering wheel movements, eye movements, physiological signals and self-reported driving performance. The results show that the effects of visual and cognitive load affect driving performance in qualitatively different ways. Visual demand led to reduced speed and increased lane keeping variation. By contrast, cognitive load did not affect speed and resulted in reduced lane keeping variation. Moreover, the cognitive load resulted in increased gaze concentration towards the road centre. Both S-IVIS had an effect on physiological signals and the drivers’ assessment of their own driving performance. The study also investigated differences between the three experimental settings (static simulator, moving base simulator and field). The results are discussed with respect to the development of a generic safety test regime for In-vehicle Information Systems.     

A model for explanation of personal attitudes toward traffic of candidate drivers attending drivers’ courses: Risky candidate driver’s attitude model

There exist a good many scientific studies into risk-taking and risky behavior displayed by reckless drivers; however, there are only a few studies into attitudes towards the traffic displayed by candidate drivers. The present study aims to investigate the dimensionality of candidate attitudes’ drivers. Data were collected from questionnaire completed by 258 candidate drivers, and were divided into two sets. The first data was used to explore the underlying factor structure and five latent factors were derived; Factor A Attitude towards drinking and driving; Factor P positive attitude toward traffic; Factor S speeding; Factor T traffic flow vs. rule obedience; and Factor R risky candidate driver’s attitude. The second data set was used to confirm this factorial structure using confirmatory factor analysis. The fit indices showed that the model fitted the data well.     

It’s about time! Earlier take-over requests in automated driving enable safer responses to conflicts

Automated driving (AD), which takes full responsibility for the driving task in certain conditions, is currently being developed. An important concern in AD is how to design a take-over request (TOR) that mitigates automation effects (e.g., delayed responses to conflict scenarios) that previous literature from simulator experiments has shown can occur. To address this concern, this study aims to investigate and compare driver responses to TORs and a lead-vehicle cut-out scenario under three conditions: (1) after a period of AD with a TOR issued early (18 s time-to-collision), (2) same as (1) except with a TOR issued late (9 s time-to-collision), and (3) baseline, with adaptive cruise control (ACC). This paper also compares the results to those of a previous study using the same conflict scenario but with near-perfect assisted driving system (SAE Level 2). The lead-vehicle cut-out scenario was encountered on a test track after 30 minutes driving with either ACC or AD. In AD the TOR was issued prior to the conflict object was revealed to the participants when the lead vehicle performed the cut-out (at conflict onset). This TOR strategy differed from previous driving-simulator studies that issued the TOR at conflict onset. The participants had to respond by steering and/or braking to avoid a crash. Our findings show that, independent of TOR timing, the drivers required similar amounts of time to 1) direct their first glance to the human–machine interface, 2) look forward, 3) end their secondary task, 4) put their hands on the steering wheel, and 5) deactivate automation. However, when the TOR was issued early rather than late, they started to brake earlier (even before conflict onset). All participants successfully managed to avoid crashing with the object, independent of the condition. AD with an early TOR resulted in the earliest response, while ACC drivers responded slightly earlier than the drivers in AD with the late TOR. Our findings do not support the findings of severe automation effects in previous driving-simulator studies. One reason for the difference is that when a TOR is issued prior to conflict onset, drivers are given the time needed for their preparatory actions (e.g., placing hands on the wheel, deactivating AD) that is not needed when driving with ACC or in manual driving (baseline), before having to respond to the conflict scenario. Thus, at conflict onset the drivers in AD are as ready to act (hands on wheel, eyes forward) as the drivers in the baseline and can perform an avoidance manoeuvre similar as to the baseline drive. Overall, the present study shows that AD does not need to end up in a highly critical situation if the TOR is issued early enough. In fact, AD with an early TOR may be safer than driving with ACC, because in the former drivers are more likely to brake earlier in preparation for the conflict. Finally, a TOR clearly communicates the need for drivers to resume manual control and handle potential events when AD has been deactivated. In our study, once the drivers had taken control, they clearly understood their responsibilities to respond to the conflict, in contrast to a previous study with a similar, near-perfect assisted driving system.     

Effect of time pressure on steering control of the drivers in a car-following situation

The current study focused on analyzing steering control of the drivers during a car-following situation under increasing time pressure conditions. A driving simulator experiment was conducted on ninety-two participants to assess steering performance measures. Five different steering control measures: Variability in Steering Angle (VSA), Steering Reversal Rate (SRR), Steering Speed (SS), Stability of Steering Control (SSC), and Maximum Steering Swerve (MSS) were examined under No Time Pressure (NTP), Low Time Pressure (LTP), and High Time Pressure (HTP) driving conditions. Repeated measures ANOVA (for continuous data) and Friedman’s test (count data) with post-hoc analysis and Generalized Estimating Equation (GEE) modeling technique were used to investigate the influence of time pressure and different predictor variables. The statistical analysis showed that time pressure driving conditions significantly affected steering control of the drivers. The pairwise comparison of time pressure conditions revealed that HTP significantly affected most of the steering control measures as compared to LTP. Further, a GEE model also exhibited similar results where steering control measures were substantially influenced by HTP as compared to LTP. Moreover, in addition to time pressure conditions, demographic characteristics showed significant influence on steering control measures. The GEE model results showed that female drivers performed 13% more steering corrections (5° SRR) which led to better SSC by 124.44% than male drivers. Additionally, it was discovered that young-aged and experienced drivers took extra steering efforts to control lateral position of the vehicle by increasing 53.50% SS and 1% SRR compared to middle-aged and inexperienced drivers. The findings from the current study revealed that drivers undergo fast and abrupt steering maneuvers under time pressure conditions. The research approach demonstrated in the current study can be beneficial to discriminate minimum requirement of steering efforts and set-up threshold values for various steering evasion techniques to control and maintain safe lateral position during car-following maneuvers.     

Effect of strength and direction of haptic cueing on steering control during near lane departure

The present study compared two distinct approaches to designing driving assistance devices. These devices aim to facilitate steering responses by delivering directional pulses on the steering wheel when lane departure is imminent. In one case, the aim is to prime the corrective gesture through a haptic cue in the direction of the lane centre (motor priming). The other approach consists of eliciting a compensatory reflex reaction by means of a jerk of the steering wheel in the opposite direction. Central to this investigation are the safety benefits of the devices and the ability of drivers to remain in full control of their steering responses. The steering behaviour of 18 participants during near lane departure in bends and in straight lines was analysed. The strength and direction of haptic cueing was manipulated. The results show that drivers were always able to control the direction of the steering response when the haptic cue was delivered. No reflex counteraction was observed, whatever the strength or the direction of the stimulus. The fastest responses were observed when the cue was directed toward lane departure, especially when cueing was strong. However, these did not necessarily lead to the fastest returns to a safe position in the lane when compared with motor priming toward the lane centre. The latter yielded improved manoeuvre execution as soon as the steering movement was initiated. These results are discussed in relation to the sensorimotor and cognitive processes involved in steering behaviour. Their implications for the design of haptic-based lane departure warning systems are considered.     

Situational specificity of trait influences on drivers’ evaluations and driving behaviour

This study explored the influence of anger and anxiety traits on driver evaluations and behaviour during a simulated drive. Forty-eight licensed drivers completed identical simulated driving tasks during which they rated levels of current anger, calmness and frustration or levels of danger, calmness and difficulty. Anxiety-prone drivers made higher difficultly evaluations and generally drove more cautiously. Anger-prone drivers gave higher ratings of anger and frustration, but their evaluations and anger tendencies were unrelated to their general driving behaviours. When driving behaviours in high and low anger-provoking situations were contrasted, in low anger-provoking situations, drivers higher in trait anger reported more anger and frustration and also drove faster and with more sideward movement. When driving situations were considered separately, although not overall, behaviour and evaluations were related: when forced to move sideward, drivers reported more frustration; when forced to drive more slowly, they reported more anger, and subsequently increased acceleration, throttle pressure and steering wheel use. These relationships were not moderated by trait anger. Irrespective of trait anger, drivers become angry when impeded, or in other anger-provoking situations, only drivers with high trait anger become angry and behaved aggressively in circumstances most would not consider provocative.     

A new approach to identifying the effect of diabetic peripheral neuropathy on the ability to drive safely

The purpose of this study was to estimate the potential for impaired driving performance in current drivers with diabetic peripheral neuropathy compared to healthy controls. We analysed, using a driving simulator, three important aspects of driving - use of the accelerator pedal, steering wheel and eye-steering coordination - to test for any differences, and then to integrate these findings to identify a unique pattern of changes in people driving with diabetic peripheral neuropathy. Patients with diabetic peripheral neuropathy displayed differences in use of the accelerator pedal compared to healthy control drivers (p < 0.05) which could be a direct consequence of their sensorimotor impairment due to diabetic peripheral neuropathy. Drivers with DPN used the more extreme high and low positions of the pedal to a greater extent than the Control group who exhibited a more graded use of the accelerator pedal over the mid-range. Eye-steering coordination was also different in drivers with diabetic peripheral neuropathy (p < 0.05) and, as it improved during the second drive, becoming closer to healthy drivers’ values, the occasional loss of control experienced during driving reduced. These insights demonstrate that diabetic peripheral neuropathy affects multiple aspects of driving performance suggesting the need for an integrated approach to evaluate the potential for driving safely in this population.     

Effectiveness of the compensatory strategy adopted by older drivers: Difference between professional and non-professional drivers

It has been a controversial issue for the effect of ageing population on driving safety. Apparently, drivers’ physiological and cognitive performances deteriorate with age. However, older drivers may compensate for the elevated risk by adjusting their behaviors, known as compensatory strategy. Despite the extensive research on this topic, the compensatory strategy of older professional drivers is not well understood since many studies focused on the differences in compensatory behavior between older and young drivers. Professional drivers tend to be more skillful and able to cope with the unfavorable driving environments, thus presenting a higher capability to mitigate the risk. This study attempts to examine the compensatory behavior and its safety effect amongst older professional drivers, as compared to those of older non-professional drivers, using the driving simulator approach. In the driving simulator experiment, participants were asked to follow a leading vehicle for one hour, and two sudden brake events were presented. 41 (mid-aged and older) drivers completed the driving tests. Each participant was required to complete a car-following test, either under high or low traffic flow conditions. Performance indicators include driving capability (i.e. lateral control, longitudinal control, and brake reaction time) and compensatory behavior (i.e. average speed, and time headway). Additionally, two modified traffic conflict measures: time exposed time-to-collision (TET) and time integrated time-to-collision (TIT) are applied to indicate the traffic conflict risk. The random parameter Tobit models were estimated to measure the association between conflict risk and driver attributes, and random intercept models were used to assess other driving performance indicators. Results show that despite the impaired lateral control performance and longer brake reaction time of older drivers, the likelihood of severe traffic conflict of older drivers is lower than that of mid-aged drivers. Furthermore, though both older professional and older non-professional drivers adopted longer time headway, the reduction in the risk of severe traffic conflict is more profound among the older professional drivers. Such findings suggest that older professional drivers are more capable of mitigating the possible collision risk by adopting the compensatory strategy, as compared to older non-professional drivers. This justifies the existence of compound effect by the compensatory strategy of older driver and better driving skills of professional driver. This research provides useful insights into driver training and management strategies for employers, as older drivers would become a major cohort in the transportation industry.     

Measuring driving workload of heavy vehicles at roundabouts

Correctly designed roundabouts proved to have positive safety and functional performances. However, they are also affected by peculiar disadvantages. In particular, they are difficult to manoeuvre, especially for heavy vehicle drivers. Despite these concerns, there are currently no driving workload metrics devoted to roundabouts.A novel methodological approach is proposed for trying to quantify workload impinging on heavy vehicle drivers when manoeuvring through complex at-grade intersections. Proper acquisition of input data constitutes the starting point for future research about ascertainment of workload for these particular road scenarios. The described procedure enables recording steering wheel angles performed by a driver when manoeuvring an articulated lorry through a complex at-grade intersection. A field trial was carried out for verifying the practical feasibility of proposed method in capturing driver’s steering behaviour. Dynamic data acquired via global navigation satellite system instrumentation were related to actual driver’s steering wheel behaviour captured by camera frames. As a complement to the experiment, selected steering behaviour metrics were calculated. Steering Entropy attributed a high difficulty level to the manoeuvres performed through the roundabout, whereas High Frequency Component and Steering Reversal Rate showed intensity and occurrences of driver’s corrections needed for controlling position of the semitrailer at the ring. It appears that even a single roundabout may represent an arduous task for drivers. The study concludes with recommendations for further research about workload imposed by roundabouts to heavy vehicle drivers, with special attention to successions of closely spaced roundabouts.     

Influence of the median opening length on driving behaviors in the crossover work zone—A driving simulation study

Work zone safety has been a major concern for drivers and transportation agencies. Considering the severe consequences of crossover work zone crashes coupled with the limited literature on the median opening length, this paper aims to investigate the influence of the median opening length on driving behaviors from a behavioral perspective in crossover work zones. A driving simulation study with 32 participants was carried out to investigate the driving performance by metrics (speed, acceleration, maximum steering wheel speed, and lane-changing trajectory) with respect to five median opening lengths. The significant differences of each driving performance metric among various median opening lengths were found in the process of crossing through the median opening on the entrance by-pass and exit by-pass. The results indicated that drivers’ speeds were always higher than the speed limits for all median opening lengths. A narrower median opening may induce risky driving behaviors such as sharp deceleration and decelerating while lane-changing, which may increase speed variance. When crossing through the median opening with a larger length, high speed variance, sluggish lane-changing operations, and improper lane-using behaviors were observed because the excessive lane-changing space provided by the larger median opening length would decrease the situation awareness and increase the speed preference heterogeneity among drivers. Finally, some traffic management strategies were proposed, which can improve the safety and mobility of crossover work zones and further provide a basis for the formulation of related standards.     

Research on effects of pattern,amplitude and frequency of pulse steering torque warnings for lane departure

Driver’s inattention is the main reason for lane departure accidents in highway traffic. In this paper, the pulse steering torque warnings technique is studied, and the effects of pattern, amplitude and frequency of pulse steering torque warnings on the effectiveness and customers’ acceptance are studied through in-door experiments based on a fixed-based driving simulator. Prototypes of lane departure warning system with twelve parameter settings were developed. Three-ways repeated measures ANOVAS and t-test are used to assess the effects of warning systems. The steering behaviors of 20 drivers during lane departure are analyzed. The experimental results show that both primary and secondary interaction of amplitude, frequency and pattern are not significant. The superimposed square pulse steering torque is more effective than triangular pulse one. There is little difference of drivers’ preference in pulse patterns. Although large amplitude is less accepted by drivers, it improves the correction maneuver greatly. 10 Hz is a preferred frequency, which achieves a compromise between effectiveness and drivers’ acceptance. Thus, the combination of small amplitude, square and mid-frequency is the best compromise for practical application.     

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.     

Car following with an inertia-oriented driving technique: A driving simulator experiment

BackgroundFor many decades, car-following (CF) and congestion models have assumed a basic invariance: drivers’ default driving strategy is to keep the safety distance. The present study questions that Driving to keep Distance (DD) is a traffic invariance and, therefore, that the difference between the time required to accelerate versus decelerate must necessarily determine the observed patterns of traffic oscillations. Previous studies have shown that drivers can adopt alternative CF strategies like Driving to keep Inertia (DI) by following basic instructions. The present work aims to test the effectiveness of a DI course that integrates 4 tutorials and 4 practice sessions in a standard PC computer designed to learn more adaptive driving behaviors in dense traffic. Methods. Sixty-eight drivers were invited to follow a leading car that varied its speed on a driving simulator, then they took a DI course on a PC computer, and finally they followed a fluctuating leader again on the driving simulator. The study adopted a pretest-intervention-posttest design with a control group. The experimental group took the full DI course (tutorials and then simulator practice). The control group had access to the DI simulator but not to the tutorials. Results. All participating drivers adopted DD as the default CF mode on the pre-test, yielding very similar results. But after taking the full DI course, the experimental group showed significantly less accelerations, decelerations, and speed variability than the control group, and required greater CF distance, that was dynamically adjusted, spending less fuel in the post-test. A group of 8 virtual cars adopting DD required less space on the road to follow the drivers that took the DI course.