Communicating safety with drivers via dynamic message signs

In recent years numerous transportation agencies have begun displaying creative safety messages like “get your head out of your apps” on dynamic message signs (DMS). DMS have been used traditionally to provide real-time information about travel times, weather conditions, construction, and incidents. Applying emotional and consequential concepts from protection motivation theory, which has a track record of leading to behavioral changes from public awareness campaigns, this study evaluates how the use of safety messages on DMS impacts driver perceptions. We find that emotions, but not consequences, impact self-reported driving behavior. Further, while drivers reported negative emotions would change their driving habits, positive messages were recalled far more often. Cell phone related messages were recalled most frequently despite being rarely displayed along roadways in Michigan where the study is conducted. Thus, the results support the use of positively themed messages with consequences that drivers perceive as realistic.     

Effects of forward collision warning technology in different pre-crash scenarios

The forward collision warning (FCW) system is expected to reduce rear-end crashes; however, its effects on driving behavior and safety have not been thoroughly investigated, specifically the effect variations between different pre-crash scenarios. To identify these variations, this study conducted a driving simulator experiment and compared the FCW’s effects between three pre-crash scenarios: the freeway scenario, the arterial scenario and the intersection dilemma zone scenario. Thirty-nine participants were involved in the experiment. The results showed that the adaptation of driver behavior in impending rear-end collision events resulted from both the FCW and the scenario. The intersection dilemma zone scenario has indications of slowing down, which encouraged drivers to take a more aggressive response strategy under the FCW; the arterial scenario might be regarded as an “easy-to-handle” situation in which a significant portion of drivers adopted moderate level of response strategy under the FCW; both the intersection dilemma zone scenario and freeway scenario have burdened driving tasks, and this might deteriorate a driver’s ability to adapt to the FCW. In addition, different types of drivers experienced varied benefits from the FCW in each scenario. The FCW would be particularly recommended for non-experienced drivers in the freeway scenario and for female drivers in the arterial scenario; moreover, in the scenario of the intersection dilemma zone, the FCW would be particularly recommended for drivers who have a crash/citation before. The results also support specific FCW designs which are able to highlight the collision risk. This study demonstrated that it would be better to indicate the effects of the FCW under the restriction of specific scenario features and develop the FCW based on that.     

驾驶中移动电话的使用：基于自我调整行为的研究视角

因使用移动电话而导致的“驾驶分心”已成为一种严重的道路安全隐患。驾驶者总体上能意识到其危害, 但在驾驶中使用移动电话的现象很普遍。以往研究不能全面地对这一矛盾予以解释, 长期以来更是忽略了对“驾驶分心中自我调整行为”进行研究, 而这一问题能够直接解释驾驶中的移动电话使用行为。从以下三个方面可以对与驾驶分心中自我调整行为有关的研究进行分析和综述：(1)驾驶中移动电话使用行为的一般规律(类型、频率和危险感知等), 驾驶者对移动电话使用行为的理解是诱发自我调整行为的基础; (2)驾驶情境下移动电话使用中可能触发的自我调整行为, 该部分将主要分析自我调整行为的类型及相关属性; (3)如何对移动电话使用行为和自我调整行为进行预测。总体上, 基于对补偿式安全信念进行理解和度量、并以此为切入点对驾驶中移动电话使用及与其有关的自我调整行为展开研究, 这将有助于更好地理解驾驶分心行为。     

Evaluating the impacts of situational awareness and mental stress on takeover performance under conditional automation

Several safety concerns emerge for the transition of control from the automated driving system to a human driver after the vehicle issues a takeover warning under conditional vehicle automation (SAE Level 3). In this context, recent advances in in-vehicle driver monitoring systems enable tracking drivers’ physiological indicators (e.g., eye-tracking and heart rate (HR) measures) to assess their real-time situational awareness (SA) and mental stress. This study seeks to analyze differences in driver’s SA and mental stress over time (i.e., successive experiment runs) using these physiological indicators to assess their impacts on takeover performance. We use eye-tracking measures (i.e., on-road glance rate and road attention ratio) as indicators of driver’s SA during automated driving. Further, we use the pre-warning normalized HR (NHR) and HR variability (HRV) as well as the change in NHR and HRV after the takeover warning as indicators of mental stress immediately before and the change in mental stress after the takeover warning, respectively. To analyze the effects of driver state (in terms of SA and mental stress) on the overall takeover performance, this study uses a comprehensive metric, Takeover Performance Index (TOPI), proposed in our previous work (Agrawal & Peeta, 2021). The TOPI combines multiple driving performance indicators while partly accounting for their interdependencies. Results from statistical analyses of data from 134 participants using driving simulator experiments illustrate significant differences in driver state over successive experiment runs, except for the change in mental stress after the takeover warning. Some significant correlations were found between the physiological indicators of SA and mental stress used in this study. Takeover performance model results illustrate a significant negative effect of change in NHR after the takeover warning on the TOPI. However, none of the other physiological indicators show significant impacts on takeover performance. The study findings provide valuable insights to auto manufacturers for designing integrated in-vehicle driver monitoring and warning systems that enhance road safety and user experience.     

The impact of safety climate on safety related driving behaviors

This study explored the impact of safety climate, age and tenure as a driver on safety related driving behaviors among 290 company drivers in Ghana. The study found a negative relationship between safety climate and studied work-related behaviors: speeding, rule violation, inattention and driving whiles tired. The study also found that age significantly predicted the extent to which drivers engaged in safety related driving behaviors. The results showed that young drivers (aged 20–35 years) engage more in risky driving behaviors relative to adult drivers (aged 36–60 years). The study also found that the tenure of a driver did not significantly affect work-related driver behaviors. The findings from this study suggests that in the quest to reduce safety related traffic accidents and its resulting consequences such as injuries, absenteeism and deaths, a critical organizational variable that organizations can use to mitigate this canker is commitment to and strict adherence to safety practices and regulations. By extension, the findings suggest, Ghana’s commitment to safety practices and enforcement of safety regulations and policies among others can help the country win the battle against road accidents.     

Assessing the effect of long-automated driving operation,repeated take-over requests,and driver’s characteristics on commercial motor vehicle drivers’ driving behavior and reaction time in highly automated vehicles

Automated Commercial Motor Vehicles (CMVs) have the potential to reduce the occurrence of crashes, enhance traffic flow, and reduce the stress of driving to a larger extent. Since fully automated driving (SAE Level 5) is not yet available, automated driving systems cannot perform all driving tasks under all road conditions. Drivers need to regain the vehicle’s control when the system reaches its maximum operational capabilities. This transition from automated to manual is referred to as Take-Over Request (TOR). Evaluating driver’s performance after TORs and assessing effective parameters have gained much attention in recent years. However, few studies have addressed CMV drivers’ driving behavior after TOR and the effect of long-automated driving and repeated TORs. This paper aims to address this gap and gain behavioral insights into CMV drivers’ driving behavior after TOR and assess the effect of the duration of automated operation before TOR, repeated TORs, and driver characteristics (e.g., age, gender, education, and driving history). To accomplish this, we designed a 40-minutes experiment on a driving simulator and assessed the responses of certified CMV drivers to TORs. Drivers’ reaction time and driving behavior indices (e.g., acceleration, velocity, and headway) are compared to continuous manual driving to measure driving behavior differences. Results showed that CMV drivers’ driving behavior changes significantly after the transition to manual regardless of the number of TORs and the duration of automated driving. Findings suggest that 30 min of automated operation intensifies the effect of TOR on driving behaviors. In addition, repeated TOR improves reaction times to TOR and reduces drivers' maximum and minimum speed after TORs. Driver’s age and driving history showed significant effects on reaction time and some driving behavior indices. The findings of this paper provide valuable information to automotive companies and transportation planners on the nature of driver behavior changes due to the carryover effects of manual driving right after automated driving episodes in highly automated vehicles.     

Investigating driving instructors: The mediating roles of driving skills in the relationship between organizational safety strategies and driver behaviours

The aim of the present study is to investigate the mediating roles of driving skills in relationship between organizational safety strategies and driver behaviours among driving instructors. Driving skills consist of perceptual-motor skills and safety skills. Driver behaviours are investigated under four factors: violations, errors, lapses, and positive driver behaviours. Participants were 132 driving instructors (108 male and 24 female). In order to measure organizational safety strategies, Organizational Safety Strategies Scale (OSSS) was developed for driving schools. Results of the principal component analyses yielded one-factor solution for OSSS. In order to test the indirect effects of organizational safety strategies on driver behaviours through driving skills, multiple mediation analyses were conducted by entering age and annual mileage as the control variables. As organizational safety strategies were stronger, driving instructors had higher levels of perceptual-motor skills, which resulted in higher violations. On the other hand, as organizational safety strategies were stronger, driving instructors had higher levels of safety skills, which resulted in less violations and lapses. It can be inferred that; organizational stronger safety strategies might have negative influences on road safety through higher perceptual-motor skills; whereas there can be positive influences on road safety through higher safety skills. In addition, both skills are related to organizational safety strategies. Hence, driving schools should consider the asymmetric relationship between perceptual-motor skills and safety skills while improving their safety strategies to decrease violations and lapses. Organizations might also develop interventions to balance the stated skills to increase road safety.     

The relationship between cognitive function and hazard perception in younger drivers

Driving is a complex task; with research suggesting cognitive function plays a significant role in driver behaviour. Recent studies have investigated the role of cognitive function in younger drivers who are experiencing brain maturation and are over-represented in crash statistics. Emerging evidence suggests poor cognitive functioning is one explanation for this high crash risk. For younger drivers, the relationship between cognitive function and driving ability has been consistently shown for speeding and lane deviations. However, the driving skill most consistently linked to crash involvement is hazard perception, which is the ability to anticipate and respond to potentially dangerous traffic situations. The aim of this study was to investigate the cognitive correlates of hazard perception in younger drivers. Seventy-nine undergraduate students completed a hazard perception test and a battery of cognitive tests that have previously demonstrated a relationship with safe driving. The newly created hazard perception test measured accuracy of hazard identification, response times when anticipating the hazard, and response times when taking action to avoid the hazard. Hazard perception accuracy was significantly related to visuo-spatial skills, executive functioning and global cognitive status. Anticipation response times were significantly related to inhibitory control, with no significant relationship found between cognitive function and action response times. These findings are discussed in line with limitations in the study. Future research into the role of specific cognitive domains could lead to the enhancement of hazard perception testing for licensing with cognitive training and assessment, with the potential to reduce the crash risk of vulnerable younger drivers.     

The influence of just-world beliefs on driving anger and aggressive driving intentions

Decades of research demonstrate that the extent to which one believes the world is just can have important interpersonal consequences. Unfortunately, most of the commonly studied consequences are negative in nature. Guided by previous research demonstrating the buffering effect of just‐world beliefs and anger, the present research explores how belief in a just world (BJW) may mitigate anger in the domain of driving anger and examines the limiting conditions of this effect. Study 1 demonstrated the expected negative relation between common measures of BJW and anger expression in a driving context. Study 2 found that the buffering effects of just‐world beliefs and driver aggression were greater when BJW was violated (vs. not). Study 3 replicated the effects on aggression and anger and established a mediational role of anger on the buffering effects of just‐world beliefs on thoughts and driver aggression. Aggr. Behav. 38:389‐402, 2012. © 2012 Wiley Periodicals, Inc.     

Improving Fitness to Drive: The Case for Hazard Perception Training

On one hand, individuals who are unfit to drive should not be allowed behind the wheel. On the other hand, being unable to drive can have significant negative consequences for some individuals, including an increased mortality risk. One potential solution to this dilemma is to use training interventions to improve fitness‐to‐drive. The problem is that, in general, post‐licensing driver training and education has a disappointing track record in terms of improving road safety. However, one type of intervention that may have the potential to buck this trend is hazard perception training. Hazard perception, which is the driver's ability to anticipate dangerous situations on the road ahead, has been found to predict both crash risk and on‐road driving performance, and can account for variance in both of these criteria that other key fitness‐to‐drive measures cannot. Crucially, there is evidence that hazard perception competence can be improved by brief computer‐based interventions, even for driver groups who are more likely to face fitness‐to‐drive challenges, such as individuals aged over 65 years or adults with attention deficit hyperactivity disorder. This article puts the case for potentially using such interventions to help individuals with fitness‐to‐drive difficulties.     

Who overtakes more? Explanatory analysis of the characteristics of drivers from low/middle and high-income countries on passing frequency

The passing manoeuvre requires a driver to make decisions and take actions which are dependent on his/her behavioural characteristics and driving ability. However, previous works on passing rate models have exclusively considered geometric and traffic-related variables. This study aims at bridging this gap by investigating the influence of driver profile (i.e., age, gender, nationality - Italian or Iranian - aggressive driving scores, driving exposure) on passing frequency. A driving simulation experiment involving 54 drivers (36 Italians, 18 Iranians) was conducted along a 6.67 km segment of a two-lane rural highway with passing manoeuvres permitted along 25% of its length. Controlled factors included traffic flow and speed in the oncoming direction, and speed in the driver direction, with a total of 27 scenarios assigned to drivers based on a 3³ confounded factorial design. A Poisson regression model was used to investigate the significance of independent variables. Age and gender and their interaction term were significant, thus the effects of age and gender on the number of passing manoeuvres are mutually interdependent. Furthermore, drivers who drive less often completed fewer overtaking manoeuvres. Sensitivity analyses were carried out to understand the magnitude of change in passing frequency attributable to a variation in the explanatory variables. The findings suggest that driver characteristics have a significant effect on passing frequency and should be considered when conducting a performance and safety evaluation of two-lane roads.     

Effects of route familiarity on drivers’ psychological conditions: Based on driving behaviour and driving environment

Route familiarity affects a driver’s mental state and indirectly affects traffic safety; however, this important factor is easily overlooked. Previous research on route familiarity has only analysed psychological states in terms of unfamiliarity and familiarity, the influence of driving behaviour and driving environment on psychological states has been ignored. As a result, the mechanisms through which the route familiarity influence driver psychological states, and vice versa, are unclear. This study proposes a quantitative framework for studying driver psychological condition and route familiarity using experimental data from a real driving task and driving environment data. The experimental data included 1022 observations obtained by 23 participants over 7 consecutive trials on 6 unfamiliar experimental routes with large differences in scenarios; environmental data were automatically extracted after segmenting a driving video through the Dilated Residual NetWorks model. The results reveal that (1) the relationship between the driver’s psychological condition and route familiarity is not monotonic and is different for straight and turning sections; (2) the driver’s psychological condition is influenced by the visual scene elements and the type of road section, and the results of the multivariate regression analysis quantified the variability of the influence; and (3) unlike a majority of findings on distracted driving, our study suggest that the driver’s attention to the external environment in the urban distracted driving state will gradually approach a ‘distraction threshold’, and the time and size of the ‘distraction threshold’ are influenced by the driver. This study can further the development of urban traffic safety research and help urban designers plan and improve urban landscapes to ensure drivers maintain stable mental states when they drive.     

A novel conceptual framework investigating the relationship between roadside advertising and road safety: The driver behaviour and roadside advertising conceptual framework

This paper proposes a conceptual framework to understand the relationship between roadside advertising signs, driver behaviour, and road safety outcomes. Roadside advertising signs are external distractions that may take a driver's attention away from safety-critical driving tasks, potentially increasing crash risk through driver distraction and inattention. Although studies report safety concerns, as a whole, the body of research in the field is inconclusive with inconsistent quality, making it difficult to draw firm conclusions. Definitive links between roadside advertising and road trauma are not yet evident, which has major consequences for road regulators' capacity to develop evidence-based policy to safely administer public roads. However, a lack of consistent evidence does not indicate an absence of risk but underscores its complexity. To address this problem, the Driver Behaviour and Roadside Advertising Conceptual Framework (DBRA framework) was developed to strategically investigate and conceptualise the phenomena of roadside advertising. A new term – “extended engagement” – has also been proposed to account for situations of prolonged attentional engagement with a roadside advertising sign. Further, it is posited that important variations in driving performance may be associated with a driver's extended engagement with a roadside advertising sign. Built on extant theories of driver behaviour and empirical research, the DBRA framework is designed to be a robust tool that encourages a common agenda for future roadside advertising research.     

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。     

Learning from experience: Familiarity with ACC and responding to a cut-in situation in automated driving

Response times to risky events have been seen to increase with the use of adaptive cruise control (ACC). It has been unclear whether driver experience with ACC mediates this increase. We compare driving in a cut-in event in a simulator both with and without system support, studying ACC as well as ACC with automatic steering. 31 participants were tested in a repeated-measures design, 10 novices and 21 previously experienced with ACC. There was no difference between responding to ACC with and without automatic steering for either group. As expected, we found an increase in response times when driving with system support for both ACC-experienced drivers and ACC-novices. However, this effect was significantly lower for those previously experienced with ACC. This indicates that there is an element of learning involved not only in knowing about system limitations, but also in responding to potential hazards.     

Does making a conversation asynchronous reduce the negative impact of phone call on driving?

Mobile phone use at the wheel has a proven negative impact on driving. This paper aims to assess whether using an answerphone instead of a normal phone reduces this negative impact. The answerphone makes communication asynchronous and splits it into three disconnected and successive phases: interaction with the voice interface, listening to the message and answering, which have been evaluated separately.The experiment was conducted on a fixed base simulator, with 30 participants (half male and female, aged from 18 to 50 years, driving at least 5000 km per year).The results show better scores for correct responses to stimuli for answerphone communications than for phone communications, although response times were higher in both communication conditions than in the driving alone condition. When the three phases of answerphone use were compared, interacting with the answerphone and listening to the message were found to be significantly less disturbing than answering, in terms of correct responses and response times.By making the conversation asynchronous, the answerphone avoids direct interaction between driver and caller. The fact that communication is under the driver’s control allows him/her to pace the interaction better. Lastly, splitting up the conversation into different phases decreases the overall task difficulty.     

Predicting the effects of cellular-phone dialing on driver performance

Legislators, journalists, and researchers alike have recently directed a great deal of attention to the effects of cellular telephone (‘cell phone’) use on driver behavior and performance. This paper demonstrates how cognitive modeling can aid in understanding these effects by predicting the impact of cell-phone dialing in a naturalistic driving task. We developed models of four methods of cell-phone dialing and integrated these models with an existing driver model of steering and speed control. By running this integrated model, we generated a priori predictions for how each dialing method affects the accuracy of steering and speed control with respect to an accelerating and braking lead vehicle. The model predicted that the largest effects on driver performance arose for dialing methods with high visual demand rather than methods with long dialing times. We validated several of the model’s predictions with an empirical study in a fixed-based driving simulator.     

The effect of sleep-need and time-on-task on driver fatigue

Both sleep- and task-related factors are thought to contribute to driver fatigue, with each factor individually associated with deteriorated driving performance. However, the relative and combined effects of these factors in the context of monotonous driving have not been well studied. This study (N = 60) investigated lateral and longitudinal vehicle control, subjective fatigue and physiological response (EEG) during three 10-minute periods of time-on-task spread across a monotonous, 2-hour simulator drive. Level of physiological sleep-need was manipulated between participants by varying the instructed time spent in bed on the night before testing (≤5h or ≥ 8 h). In addition, half of the participants in each sleep group read the applicable speed limit from periodic roadside signs whereas the others performed an arithmetic calculation, displayed on the signs, to determine the speed limit. This task manipulation has been demonstrated to reduce performance decrements over time. Results demonstrated effects of time-on-task and sleep need on self-report ratings, an effect of time-on-task on EEG indices, and an interaction of sleep-need and time-on-task on an EEG index of mental workload and on the lateral control measure of driving performance. There were no significant effects on the measure of speed variability. These results confirm that both sleep-need and time-on-task negatively affect driver state, and that time-on-task decrements in driver performance can occur in the absence of heightened sleep-need. Results also suggest that drivers with heightened sleep-need could protect their performance for a short time, perhaps by exerting effort to compensate for reduced capacity. The secondary task did not counteract declining performance.     

On-road trust and perceived risk in Level 2 automation

To encourage appropriate use of driving automation, we need to understand and monitor driver’s trust and risk perception. We examined (1) how trust and perceived risk are affected by automation, driving conditions and experience and (2) how well perceived risk can be inferred from behaviour and physiology at three levels: over traffic conditions, aggregated risk events, and individual risk events.30 users with and without automation experience drove a Toyota Corolla with driving support. Safety attitude, subjective ratings, behaviour and physiology were examined.Driving support encouraged a positive safety attitude and active driver involvement. It reduced latent hazards while maintaining saliently perceived risks. Drivers frequently overruled lane centring (3.1 times/minute) and kept their feet on or above the pedals using ACC (65.8% of time). They comfortably used support on curvy motorways and monotonic and congested highways but less in unstable traffic and on roundabouts. They trusted the automation 65.4%, perceived 36.0% risk, acknowledged the need to monitor and would not engage in more secondary tasks than during manual driving.Trust-in situation reduced 2.0% when using automation. It was 8.2% higher than trust-in-automation, presumably due to driver self-confidence. Driving conditions or conflicts between driver and automation did not affect trust-in-automation.At the traffic condition level, physiology showed weak and partially counter-intuitive effects. For aggregated risk events, skin conductance had the clearest response but was discernible from baseline in  < 50%. Pupil dilation and heart rate only increased with strong braking and active lane departure assist. For individual risk events, a CNN classifier could not identify risk events from physiology. We conclude that GSR, heart rate and pupil dilation respond to perceived risk, but lack specificity to monitor it on individual events.     

Conflicts of interest: The implications of roadside advertising for driver attention

There is growing concern that roadside advertising presents a real risk to driving safety, with conservative estimates putting external distractors responsible for up to 10% of all road traffic accidents. In this report, we present a simulator study quantifying the effects of billboards on driver attention, mental workload and performance in Urban, Motorway and Rural environments. The results demonstrate that roadside advertising has clear adverse effects on lateral control and driver attention, in terms of mental workload. Whilst the methodological limitations of the study are acknowledged, the overriding conclusion is that prudence should be exercised when authorising or placing roadside advertising. The findings are discussed with respect to governmental policy and guidelines.