Intraindividual variability in driving simulator parameters of healthy drivers of different ages

Intraindividual variability is a fundamental behavioural characteristic of aging but has been examined to a very limited extent in driving. This study investigated intraindividual variability in driving simulator measures in healthy drivers of different ages using the coefficient of variation (COV) as a variability measure. Participants were healthy volunteers who were regular drivers, who were divided into a “young” group, a “middle-aged” group, and an “old” group. They drove in two environments (rural, 72 drivers; urban, 60 drivers), under conditions of moderate and high traffic load, without and with distraction (conversation). Significant differences in COV were observed in the rural condition for headway distance and lateral position as a function of traffic load, with high traffic (without and with distraction) resulting in increased COV of headway and decreased COV of lateral position. Significant differences in COV were observed in the urban condition for headway distance only, with high traffic (without and with distraction) resulting in increased COV of headway. No age effects were found for any of the driving conditions. The results indicate that traffic load affected headway distance and lateral position in opposite directions in all three age groups: high traffic resulted in increased variability of headway in both rural and urban conditions but in decreased variability of lateral position in the rural conditions compared to moderate traffic irrespective of distraction. The study indicates that driving conditions affect the intraindividual variability of driving measures in selective ways, which may be linked to the extent of automatization of the driving variables and to adaptive changes to traffic condition challenges.     

Human factors evaluation of an in-vehicle active traffic and demand management (ATDM) system

This research study focused on the evaluation of an emulated in-vehicle Active Traffic and Demand Management (ATDM) system on Interstate 66 in Northern Virginia. Traditional ATDM systems rely on infrastructure-mounted variable message signs (VMS) to provide information (speed limits, lane availability, etc.) to the traveling public. By providing information about dynamic roadway conditions on an in-vehicle device, the ATDM may improve driving safety and performance by allowing drivers to remain consistently aware of forthcoming traffic conditions and roadway requirements; even when external signage is inaccessible. This study represents an initial investigation of an emulated in-vehicle ATDM to provide developers with design guidance and ensure that unintended consequences, such as distraction, do not undermine the potential benefits.Twenty younger and 20 older participants, accompanied by a member of the research team, experienced the following ATDM features on an in-vehicle device (IVD) mounted to the dashboard: (1) dynamic speed limits, (2) dynamic lane use/shoulder control, (3) High Occupancy Vehicle (HOV) restrictions, and (4) roadway information from variable message signs. The IVD was equipped with auditory and visual alerts notifying the driver when relevant visual information was updated. Research questions addressed distraction and driver behavior associated with use of the system. Qualitative and quantitative participant data was acquired from the instrumented vehicle, various questionnaires, and researcher observation.Several key findings were uncovered: (1) The IVD, as tested, did not warrant classification as a source of distraction according to the NHTSA guidelines; v2) There was a significant difference in eye-glance durations to the IVD when comparing the VMS alerts to both the speed limit and lane management alerts; and (3) The speed limit alert motivated participants to alter their speed (per survey results and participant speed data).     

Preventing road crashes: Do infringements for traffic offences have a deterrent effect amongst drivers aged 40+? An examination of administrative data from Victoria,Australia

This study aimed to determine whether receiving a traffic infringement has a deterring influence on subsequent risky driving, measured through risk of crash involvement.Licensing, infringements and crash data for drivers aged 40+ from the Australian state of Victoria were analysed. A case-case-time-control study design was used. Overall, the odds of receiving an infringement in the month prior to a crash were 35 per cent higher than receiving an infringement in the same month the year prior, for the case group, adjusted for the change over time in the control group (Odds Ratio = 1.35, 95% CI 1.17–1.57, p < 0.001). Rather than infringements preceding a period of reduced crash involvement, and thus potentially indicating a deterrent effect, the odds of receiving an infringement in the one-month period just prior to a crash occurring was greater. Infringements for traffic offences may not be deterring further risky driving behaviours.     

Exploring the relationships between pedestrian behaviours and traffic safety attitudes in six countries

The majority of cross-cultural research on traffic safety has investigated driver behaviour, yet in most low- and middle-income countries, where the weight of the road fatality burden is felt, motorisation rates are significantly lower than in higher-income countries. As such, this approach necessarily excludes large parts of the populations in those settings. In order to investigate the link between traffic safety attitudes and road user behaviours, this study used a self-report measure of pedestrian behaviour, applying it in six countries; Bangladesh, China, Kenya, Thailand, the UK, and Vietnam. Focus was on the relationships between a respondent’s attitude towards risky or rule violating on-road behaviours (of other road users, or more generally, not specific to pedestrians), and the extent to which they reported performing three types of risky pedestrian behaviours (i.e., intentional rule violations, errors in judgement or memory, and aggressive behaviours). Data from a sample of 3,423 individuals was subjected to a series of regression models, revealing significant links between attitudes and pedestrian behaviours in all countries, in all three behavioural factors, after controlling for age, gender, and exposure to the road environment. Differences were found between countries in the strength of these relationships, with weaker connections between attitudes and behaviours in Kenya, and stronger connections in China (with other countries in-between the two). Results are discussed in terms of the need to understand the relationships between social cognitive constructs in the specific country in which a road safety intervention is intended to be implemented.     

Prevalence and factors associated with turn signal neglect-related crashes among motorcyclists and car drivers in Vietnam

Road traffic crashes and injuries are a major societal challenge around the world. However, the majority of injuries and fatalities occur disproportionately in low-income and medium-income countries. Previous studies have concluded that risky behaviours were the main contributing factor of traffic crashes. Turn signal neglect (TSN) when making a turn is one of those risky behaviours. Unfortunately, research on TSN has been very limited. This study investigates the prevalence of TSN-related crashes and factors affecting TSN among motorcyclists and car drivers. Data was obtained from self-administered questionnaires conducted in Vietnam. The findings showed that 17.54% of motorcyclists and 14.76% of car drivers have experienced at least one crash caused by their failure to turn signals in the last three years. Additionally, fewer years having a riding/driving license, longer daily travelling time, lower frequency of turn signal use, and having received a fine due to TSN were found to be positively associated with TSN-related crashes for both motorcyclists and car drivers. The findings highlight the importance of TSN for road safety and the need for authorities to develop more effective educational strategies and to increase traffic law enforcement.     

App-based feedback on safety to novice drivers: Learning and monetary incentives

An over-proportionally large number of car crashes is caused by novice drivers. In a field experiment, we investigated whether and how car drivers who had recently obtained their driving license reacted to app-based feedback on their safety-relevant driving behavior (speeding, phone usage, cornering, acceleration and braking). Participants went through a pre-measurement phase during which they did not receive app-based feedback but driving behavior was recorded, a treatment phase during which they received app-based feedback, and a post-measurement phase during which they did not receive app-based feedback but driving behavior was recorded. Before the start of the treatment phase, we randomly assigned participants to two possible treatment groups. In addition to receiving app-based feedback, the participants of one group received monetary incentives to improve their safety-relevant driving behavior, while the participants of the other group did not. At the beginning and at the end of experiment, each participant had to fill out a questionnaire to elicit socio-economic and attitudinal information.We conducted regression analyses to identify socio-economic, attitudinal, and driving-behavior-related variables that explain safety-relevant driving behavior during the pre-measurement phase and the self-chosen intensity of app usage during the treatment phase. For the main objective of our study, we applied regression analyses to identify those variables that explain the potential effect of providing app-based feedback during the treatment phase on safety-relevant driving behavior. Last, we applied statistical tests of differences to identify self-selection and attrition biases in our field experiment.For a sample of 130 novice Austrian drivers, we found moderate improvements in safety-relevant driving skills due to app-based feedback. The improvements were more pronounced under the treatment with monetary incentives, and for participants choosing higher feedback intensities. Moreover, drivers who drove relatively safer before receiving app-based feedback used the app more intensely and, ceteris paribus, higher app use intensity led to improvements in safety-related driving skills. Last, we provide empirical evidence for both self-selection and attrition biases.     

Factors related to the use of pedestrian bridges in university students of Honduras

Considering that deaths and injuries due to run overs near pedestrian bridges (PB) are preventable events, this research aims to analyze the factors related to the use of pedestrian bridges in students of a public university of Honduras. This was made through a quantitative methodology; 330 questionnaires were applied to a sample of university students. Results suggest that 17.27% of the respondents don’t use the bridge. Most respondents (62.42%) believe it’s faster to cross the street and that using the bridge is tiresome (79.90%). Pedestrian bridges are also considered to be unsafe places, prone to robberies. Pearson’s r coefficient determined that this belief is significantly associated with the perception of cleanliness, quality of the infrastructure and illumination. There is a correlation between stress and considering the use of the bridge as a tiresome activity. A logistic regression model determined that significant variables explained the use of the PB included: being in a hurry, believing it’s faster to cross the street, thinking that PBs have a bad infrastructure, laziness and thinking that using the PB is tiresome, all of them reducing the chance that someone will use the bridge. On the other hand, non-significant variables in the model included: age, considering that using the PB is stressful, thinking that crossing the street is stressful, thinking PBs have good illumination. Safety related variables were not able to discriminate between users and non-users. These results are discussed in the light of previous research and their implication for public policy and future research.     

Distressed in the queue? Psychophysiological and behavioral evidence for two alternative car-following techniques

BackgroundNature offers numerous examples of animal species exhibiting harmonious collective movement. Unfortunately, the motorized Homo sapiens sapiens is not included and pays a price for it. Too often, drivers who simply follow other drivers are caught in the worst road threat after a crash: congestions. In the past, the solution to this problem has gone hand in hand with infrastructure investment. However, approaches such as the Nagoya Paradigm propose now to see congestion as the consequence of multiple interacting particles whose disturbances are transmitted in a waveform. This view clashes with a longlasting assumption ordering traffic flows, the rational driver postulate (i.e., drivers’ alleged propensity to maintain a safe distance). Rather than a mere coincidence, the worldwide adoption of the safety-distance tenet and the worldwide presence of congestion emerge now as cause and effect. Nevertheless, nothing in the drivers’ endowment impedes the adoption of other car-following (CF) strategies. The present study questions the a priori of safety-distance, comparing two elementary CF strategies, Driving to keep Distance (DD), that still prevails worldwide, and Driving to keep Inertia (DI), a complementary CF technique that offsets traffic waves disturbances, ensuring uninterrupted traffic flows. By asking drivers to drive DD and DI, we aim to characterize both CF strategies, comparing their effects on the individual driver (how he drives, how he feels, what he pays attention to) and also on the road space occupied by a platoon of DD robot-followers.MethodsThirty drivers (50% women) were invited to adopt DD/DI in a driving simulator following a swinging leader. The design was a repeated measures model controlling for order. The CF technique, DD or DI, was the within-subject factor. Order (DD-DI / DI-DD) was the between-subjects factor. There were four blocks of dependent measures: individual driving performance (accelerations, decelerations, crashes, distance to lead vehicle, speed and fuel consumption), emotional dimensions (measures of skin conductance and self-reports of affective states concerning valence, arousal, and dominance), and visual behavior (fixations count and average duration, dwell times, and revisits) concerning three regions of the driving scene (the Top Rear Car –TRC- or the Bottom Rear Car –BRC- of the leading vehicle and the surrounding White Space Area -WSA). The final block concerned the road space occupied by a platoon of 8 virtual DD followers.ResultsDrivers easily understood and applied DD/DI as required, switching back and forth between the two. Average speeds for DD/DI were similar, but DD drivers exhibited a greater number of accelerations, decelerations, speed variability, and crashes. Conversely, DI required greater CF distance, that was dynamically adjusted, and spent less fuel. Valence was similar, but DI drivers felt less aroused and more dominant. When driving DD visual scan was centered on the leader’s BRC, whereas DI elicited more attention to WSA (i.e., adopting wider vision angles). In spite of DI requiring more CF distance, the resulting road space occupied between the leader and the 8th DD robot was greater when driving DD.     

On-to-off-path gaze shift cancellations lead to gaze concentration in cognitively loaded car drivers: A simulator study exploring gaze patterns in relation to a cognitive task and the traffic environment

Appropriate visual behaviour is necessary for safe driving. Many previous studies have found that when performing non-visual cognitive tasks, drivers typically display an increased amount of on-path glances, along with a deteriorated visual scanning pattern towards potential hazards at locations outside their future travel path (off-path locations). This is often referred to as a gaze concentration effect. However, what has not been explored is more precisely how and when gaze concentration arises in relation to the cognitive task, and to what extent the timing of glances towards traffic-situation relevant off-path locations is affected. To investigate these specific topics, a driving simulator study was carried out. Car drivers’ visual behaviour during execution of a cognitive task (n-back) was studied during two traffic scenarios; one when driving through an intersection and one when passing a hidden exit. Aside from the expected gaze concentration effect, several novel findings that may explain this effect were observed. It was found that gaze shifts from an on-path to an off-path location were inhibited during increased cognitive load. However, gaze shifts in the other direction, that is, from an off-path to an on-path location, remained unaffected. This resulted in on-path glances increasing in duration, while off-path glances decreased in number. Furthermore, the inhibited off-path glances were typically not compensated for later. That is, off-path glances were cancelled, not delayed. This was the case both in relation to the cognitive task (near-term) and the traffic environment (far-term). There was thus a general reduction in the number of glances towards situationally relevant off-path locations, but the timing of the remaining glances was unaffected. These findings provide a deeper understanding of the mechanism behind gaze concentration and can contribute to both understanding and prediction of safety relevant effects of cognitive load in car drivers.     

Effects of speed display signs on driving speed at pedestrian crossings on collector streets

This study was designed to evaluate the short- and long-term effects of speed display signs on driving speed at pedestrian crossings in a low-speed (40 km/h) urban environment. Driving speeds were compared 1 week before installation, after installation (1 week; 1 month; 3 months; 5 months) and 1 week after removal. The main results showed that the speed displays decreased the mean speed by 0.5–2.9 km/h, which translates to a 4–22% drop in pedestrian fatality risk. Furthermore, there was a drop in the proportion of speeding vehicles and approaching speed of individual vehicles. The decrease in speed persisted over time, suggesting that speed displays may reduce speeds in the long term. In conclusion, installing speed displays at pedestrian crossings on collector streets reduces driving speeds and could contribute to the safety of pedestrians.