Efficacy of haptic blind spot warnings applied through a steering wheel or a seatbelt

This study evaluates the efficacy of haptic feedback for the Blind Spot Warnings (BSWs) that are delivered to a driver through a steering wheel or a seatbelt. To this end, we developed a virtual driving simulator that implemented potential side collision scenarios. Haptic BSWs were issued as a vibrotactile alert during lane changes if a car in the target lane approached from the participant’s blind spot at a faster speed. The two haptic warning types were assessed through a human factors experiment with participants of two age groups: younger (30–40 years) and older (50–60 years). No warning condition was also included as the control condition. As performance measures, the Collision Prevention Rate (CPR) and the Minimum Distance by which a collision was Avoided (MDA) were collected. As preference measures, the participants’ perception of usefulness of the haptic warnings and their overall satisfaction were used. Experimental results showed that the highest CPR, the longest MDA, and the highest preference were achieved when BSWs were delivered through the steering wheel. For the seatbelt BSW, the CPR and MDA did not increase with statistical significance than those of the no-warning condition, but the participants felt that the haptic seatbelt was useful with high satisfaction. Interestingly, the scores of perceived usefulness and satisfaction were higher with the older group, suggesting that older drivers can be more willing to accept these new types of warning. In addition, the experiment suggested several factors that need to be studied to further improve the performance and preference of haptic BSW, such as warning issue timing and vibration intensity.     

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.     

Matters of State: Examining the effectiveness of lane departure warnings as a function of driver distraction

Lane departure warnings (LDW) have the potential to mitigate a significant number of lane departure crashes. Such safety benefits have yet been realized, in part due to drivers deactivating LDW systems. Perceived false alarms—where drivers receive a warning but feel the warning was unnecessary or incorrect—could lead to system disuse. In part, this could be a failure of LDW systems to account for the state of the driver. The current study investigated whether LDWs were more effective for drivers when they were distracted compared to when they were undistracted, using a high-fidelity driving simulator. During distracted lane departures, drivers with LDW responded faster and had less severe lane departures than drivers without LDW. During undistracted lane departures, there was no evidence of a benefit of LDW over no warning. These results suggest that lane departure warnings are most effective when drivers are distracted. This study suggests a need for driver state monitoring systems to enable adaptive automation.     

Responses to visual,tactile and visual–tactile forward collision warnings while gaze on and off the road

The objective of the current driving simulator study (N = 20) was to assess brake reaction time (BRT) and subjective experiences of visual (V), tactile (T), and visual–tactile (VT) collision warnings when the drivers’ visual orientation was manipulated between four locations (i.e., road and three different mirror locations). V warning was a blinking light in a windscreen, T warning was implemented by a vibrating accelerator pedal, and VT warning was their synchronous combination. The results showed that all the warning stimuli were detected in 100% accuracy in all visual orientations, but T and VT warnings produced significantly faster BRTs when compared to V warning. It was found that BRT to V warning was the slowest while observing the furthermost side mirror. However, BRTs following T and VT warnings remained unaffected by the visual orientations. Both the objective BRT measurements and subjective evaluations indicated a superiority of T and VT warnings against a sole V warning, not only in general terms, but also separately for different visual orientations.     

The role of edge lines in curve driving

In order to evaluate the role of edge lines in curve driving we examined steering behaviour in the face of unexpected gradual changes in road geometry. Experienced drivers (N = 13) operating a fixed-base driving simulator steered a car along a single-lane (3.80 m or 7.60 m wide) winding road. The experimental track consisted of eight 90° curves with radii of curvature varying between 75 m and 500 m, separated by 500-m long straight line segments. The model-based nature of the simulator was used to create unexpected online changes in road geometry, implemented through a gradual displacement of one or both edge lines while drivers steered around the delineated bend. Although they regulated their speed as a function of road curvature, drivers were found to consistently cut into and out of the curves. When the edge lines did not move, drivers stabilized their lane position during the 20°–70° curve segments, adopting a position closer to the interior edge line for the narrower lane width and smaller radii of curvature. Motion of the interior edge line, whether inward or outward, gave rise to systematic changes in lane position, while motion of the exterior edge line did not affect driving behaviour. Overall, the results point to a visuo-motor strategy of steering based on zeroing-out changes in the rate of change of angular bearing of the tangent point.     

Crash avoidance and driver assistance technologies – Are they used?

Crash avoidance technologies have potential to mitigate collisions, and actual crash reductions have been identified for some systems. This study measured observed on-off rates of these technologies as an indicator of use, with a focus on lane maintenance systems (i.e., designed to keep vehicles within lanes by warning, braking, and/or steering) and studied factors that might increase their acceptance and use. Vehicles from nine manufacturers fitted with lane maintenance systems were observed at service departments during 2016. Systems were turned on in 51% of 983 vehicles. The activation rate was higher for systems with braking/steering interventions and vibrating warnings and decreased with total mileage. Large proportions of front crash prevention (93%), blind spot monitoring (99%), rear cross-traffic alert (97%), and driver monitoring alert (90%) systems were enabled, and most optional settings were set to factory defaults. Owner surveys linked to observations showed that drivers who had lane maintenance systems turned off believed warnings were distracting and unnecessary compared with drivers whose systems were on.     

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.     

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.     

Effect of auditory in-vehicle warning information on drivers’ brake response time to red-light running vehicles during collision avoidance

There is usually a high red-light running (RLR) collision rate at signalized intersections because of the unpredictability of dangerous RLR vehicles traversing intersections illegally. The RLR collision warning systems can help drivers be aware of the red-light running (RLR) vehicles and take collision avoidance actions timely. The objective of this paper is to evaluate the effects of auditory warning information on brake response time (RT) to red-light running vehicles during the collision avoidance process based on a driving simulator experiment. Warning status (e.g., warning vs. no warning), warning lead time (3 s vs. 5 s) and warning content (directional information vs. undirectional information) were considered to examine the effectiveness of the RLR collision warning system under different conditions. The experiment results showed that the auditory warning information can effectively reduce brake RT and collision occurrence rate and RT is the most influential variable on the collision occurrence. Although early warning is more effective than late warning in reducing brake RT and collision rate, the late warning can still lower the collision rate by 37%. However, the directional warning information did not have apparent advantages over the undirectional warning information. The findings of this study are helpful for the designers of RLR collision warning systems to enhance the effectiveness of the systems’ application on traffic safety.     

Driving performance while using a mobile phone: A simulation study of Greek professional drivers

PurposeThe current study aims to assess the driving performance of professional drivers while using a mobile phone.Material and methodsA sample of 50 male professional drivers participated in the study. The sample was drawn conveniently from the professional drivers’ registries and the main taxi ranks. The inclusion criteria were: (a) age above 18 years, (b) possession of a driving license, (c) sufficient reading, writing, and communicating skills, (d) informed consent prior to participation. Laboratory tests were conducted using the VS500M driving simulator manufactured by Virage Simulation Inc. The intervention involved different tasks/assignments: (a) driving without using a mobile phone (Control time), (b) driving while having a conversation on the mobile phone, (Task_1), (c) driving while reading out loud text messages (Task_2) and, (d) driving while texting (Task_3). Differences in the driving performance between the control time and the time with assignments, were examined. The participants were evaluated on the followings outcome measures: (a) variation of the steering position per second, (b) following distance per second, (c) variation of the lateral lane position per second, and (d) sum of squared acceleration per second.ResultsThe analysis indicated that “variation of the steering position per second” was significantly affected by “text-message reading” [t(50) = −5.443; p < 0.0001] and “texting” [t(50) = −5.442; p < 0.0001]. A significant main effect was observed in terms of the “following distance per second” and the “variation of the lateral lane position per second” for all the three mobile phone assignments. Lastly, the “sum of squared acceleration per second” was significantly decreased during conversation on the phone [t(50) = 2.713; p = 0.009] as well as during texting [t(50) = 3.428; p = 0.001] as compared with the control time.ConclusionsThe study is among the few existing experimental studies in a country with one of the highest road fatalities in Europe but with limited evidence on road traffic behaviour. This study could guide the design of large-scale simulation studies aiming to explore the impact of mobile phone on driving behaviour.     

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.     

User-related assessment of a Driver Assistance System for Continuous Support – A field trial

A Driver Assistance System for Continuous Support continuously evaluates the status of the host vehicle as well as the surrounding traffic based on information from on-board sensors. When the system detects a hazard, it issues a warning to the driver, depending on the degree of the hazard. The effects of this system on driver behaviour and acceptance were evaluated in a field trial carried out in 2013. Twenty-four drivers took part in test drives with a within-subject design along a 53 km test route containing motorway and rural-road sections. Driving data was logged and the test drivers were observed by means of an in-car observation method (Wiener Fahrprobe); in this case by two observers in the car along with the driver. Questionnaires were used to assess the drivers’ comprehension of and reaction to the system. The system was successful in affecting driver behaviour in terms of lower speed when negotiating curves. Positive effects were found in the form of better speed adaptation to the situation during driving with the system activated. Also, lane choice and lane change improved with the system on. When it came to speed limit compliance, driving speed in general and longitudinal and lateral positioning, no effects could be found. No major differences were found regarding distance to the vehicle in front, overtaking manoeuvres, stopping behaviour at intersections, driving against yellow at traffic lights and interaction behaviour with other road users while driving with or without the system. On the negative side, it was noted that only during driving with the system activated did the test drivers make turns at intersections at too high speeds. In addition, more errors associated with dangerous distance to the side were observed with the system activated. In terms of the emotional state of the driver, the only difference found was that the drivers felt an increase in irritation. Regarding subjective workload, the drivers only assessed one item, i.e. whether their performance decreased statistically significantly while driving with the system. The test drivers were of the opinion that the system was useful, and that it would enhance safety especially in overtaking manoeuvres on motorways. The blind-spot warning was found especially useful in the overtaking process. The drivers appreciated the fact that the system did not give information all the time.     

Factors influencing drivers’ reading and comprehension of on-board traffic messages

IntroductionWhen variable message signs (VMS) or on-board traffic information systems are used, it is essential that while driving, motorists read and understand the information as soon as possible in order to make appropriate decisions to increase road safety and/or facilitate traffic flow. Thus, it is important to investigate the factors that may increase fast reading and comprehension of on-board traffic information.ObjectivesWe examined the influence of the type of message (warnings vs. recommendations), location of the pictogram (top or bottom of the text), type of display device (IPhone, Blackberry, or Tablet) and its position (horizontal or vertical) on drivers’ fast reading and comprehension of on-board messages provided via in-vehicle system. Moreover, we were interested in drivers’ acceptability of in-vehicle system.MethodForty-nine drivers (M_Men = 32, 19–65 years) participated to a reading and comprehension task while travelling on a desktop driving simulator. Participants were exposed to two series of 11 traffic messages displayed on one of the three devices. Reading and comprehension times were measured (= milliseconds) for each message. At the end, they had to fill in a questionnaire on their beliefs about on-board traffic messages and in-vehicle system.ResultsDrivers expressed a positive attitude toward on-board traffic messages and in-vehicle system. Reading and comprehension times were of approximately 4 seconds and were longer for warnings as compared to recommendations. The pictogram placed at the top of the text, the tablet and the vertical display device facilitated fast reading and comprehension.     

Aging effect on detectability,criticality and urgency under various auditory conditions

The objective of the study was to investigate the relationship between different components of an auditory warning signal and determine elderly driver’s detection, criticality and urgency perceptions under varied auditory warning conditions. A laboratory study was conducted involving 28 younger and 28 older adults. A pure-tone audiogram was administered for quantification of the participant’s hearing level (in dBHL) prior to the test protocols. Audiogram was conducted in a sound isolated booth. The main experiment investigated the effects of frequency, temporal characteristics, aging, and noise on detectability, caution and perceived urgent levels. Method of adjustment was used by the subjects to adjust the sound pressure level (dBA) till they detected, or felt caution or urgent. Overall, the results indicated that elderly had higher sound pressure threshold than younger individuals in all the sessions (i.e., detectability, caution and urgency). Elderly were found to have higher hearing thresholds especially at 4000 Hz. Higher frequencies were also seen to require less sound pressure thresholds to convey feeling of caution and urgency. Sound pressure threshold to convey the feeling of urgency was the lowest for 2000 Hz and 4000 Hz with 1000 Hz requiring the highest threshold intensity. In conclusion, current study findings suggest frequency, temporal and spectral components to influence a person’s criterion. We would recommend the use of complex tones (multi-components) having high frequency around 2000 Hz for detection, warning and urgent conditions.     

Warnings given to observers can eliminate order effects

ObjectivesThe aim of the study was to examine the impact of warnings on order effects in attributions of ability.MethodQualified soccer coaches (N = 146) rated the ability of two soccer players (a control and target player) each shown, on video, performing a passing task eight times. For the control player, all participants saw the same footage in the same order. For the target player, participants viewed the same footage with half viewing a declining (successful to unsuccessful) performance pattern and half viewing an ascending pattern. Additionally, coaches either received no warning of the danger of order effects, a warning prior to viewing any footage, a warning prior to viewing the target player or a warning prior to rating the target player.ResultsResults indicated that primacy effects were observed in the no warning condition and the warning prior to rating the target. However, when warnings were given prior to observing the target player no order effects were observed.ConclusionThe results indicate that order effects can be eliminated by warning observers of the phenomenon.     

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.     

Efficacy and feeling of a vibrotactile Frontal Collision Warning implemented in a haptic pedal

A haptic pedal has been designed to emulate the behaviour of a common vehicle pedal and render superimposed vibrations with different characteristics. It was installed in a driving simulator, as an accelerator pedal with the secondary function of a vibrotactile Frontal Collision Warning (FCW). The efficacy and feeling of this solution was tested with 30 subjects using vibrotactile signals with 0.50, 1.05, and 1.60 Nm, at 2.5, 5, and 10 Hz, against a baseline visual FCW. Participants had to match the speed of a leading vehicle when the FCW was triggered. Their braking response was evaluated in terms of brake reaction time, matching speed time, control of velocity and headway reduction. Driver’s feelings were assessed with Kansei methodologies. Haptic stimuli were found to be more effective than visual signals, and the characteristics of the vibration also influenced the results. The best performance was achieved at the maximum amplitude, and in the range between 5 and 10 Hz. The perceived functionality and discomfort followed a trend coherent with the objective measurements. The conclusions of this study may be applied to develop effective and safe warning systems in vehicles, limiting the annoyance that they might cause to drivers.     

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.     

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.     

Driving around bends with or without shoulders: The influence of bend direction

Paved shoulders have long been used to create “forgiving” roads where drivers can maintain control of their vehicles even when as they drift out of the lane. While the safety benefits of shoulders have been well documented, their effects on driver behavior around curves have scarcely been examined. The purpose of this paper is to fill this gap by assessing whether the addition of shoulders affects driver behavior differently as a function of bend direction. Driver behavior in a driving simulator was analyzed on left and right curves of two-lane rural roads in the presence and absence of 0.75-m and 1.25-m shoulders. The results demonstrated significant changes in drivers’ lateral control when shoulders were provided. In the absence of oncoming traffic, the shoulders caused participants to deviate more toward the inner lane edge at curve entry, at the apex and at the innermost position on right bends but not left ones. In the presence of oncoming traffic, this also occurred at the apex and the innermost position, leading participants to spend more time off the lane on right curves. Participants did not slow down in either traffic condition to compensate for steering farther inside, thereby increasing the risk of lane departure on right curves equipped with shoulders. These findings highlight the direction-specific influence of shoulders on a driver’s steering control when driving around bends. They provide arguments supporting the idea that drivers view paved shoulders as a new field of safe travel on right curves. Recommendations are made to encourage drivers to keep their vehicle within the lane on right bends and to prevent potential interference with cyclists when a shoulder is present.