Cyclist strategies and behaviour at intersections. Conscious and un-conscious strategies regarding positioning

Severe and even fatal accidents between cyclists and motor vehicles commonly occur at intersections. Many of these accidents occur with right-turning vehicles, with drivers not observing an adjacent cyclist. Few structured investigations exist regarding the interaction between cyclist and motor vehicle, and factors in need of study are how infrastructure and vehicle properties affect human decision-making and cycling behaviour. Therefore, a bicycle simulator study was performed, where vehicle type, presence of lane markings and lane width were systematically varied in a scenario with a cyclist approaching a vehicle from behind, at a signalized city intersection. 33 participants cycled through 8 intersection variants each. Data on cycling trajectories, stopping points and speed was coupled with survey data from the participants, and semantically categorized verbal responses to questions regarding strategy for choice of stopping point. Results show that all three factors (vehicle type, lane markings and available vehicle-adjacent space) significantly affects cyclists’ behaviour and conscious strategies. Participants were more cautious in the presence of a truck than a car, reflected in choice of position when cycling and stopping, and in explicit verbalisations regarding perilous aspects of the situation and their conscious and strategic choice of positioning. Available lateral space also affected stop positions and feeling of safety (expressed verbally). Presence of bicycle lane markings made the cyclists inclined to continue into the space to the right of the vehicle. This was revealed by their positioning and speed, and also apparent in the verbal expressions, especially the positive remarks on the situation and conditions. However, the perceived comfort with lane markings present was actually lower than when they were missing. Cyclist type (slow, moderate, or fast) matters with the self-reported faster cyclists being more prone to stop to the right than the slower one.     

The perceived effectiveness of road safety interventions: Regulation of drivers’ behavioral intentions and self-consciousness

We consider road safety interventions to be potential sources of social influence, altering the intentions and behaviors of drivers when they are perceived by the latter as effective. We also consider that perceiving their effectiveness depends on drivers’ self-consciousness. 852 drivers replied to a questionnaire measuring dispositional self-consciousness, the perception of the effectiveness of 10 road safety interventions, and reported intentions and behaviors related to speeding and drinking and driving. The results revealed several phenomena: (1) interventions were perceived as related to penalty/surveillance or social communication (factor analysis); (2) the former were perceived as more effective than the latter; (3) the perceived effectiveness of road safety interventions was moderately correlated with intentions and behaviors; (4) this link was stronger for interventions of the penalty/surveillance type; (5) age, level of education, frequency of use of a vehicle and gender were moderately associated with the perception of these interventions; (6) self-consciousness (in particular its public dimension) had an additional positive association with this perceived effectiveness. These results are discussed from a practical and methodological point of view.     

Investigating relationships among perceptions of yielding,safety, and comfort for pedestrians in unsignalized crosswalks

Interactions with other road users influence the perceived safety and comfort of pedestrians. Yet the relationships among perceptions of yielding, safety, and comfort are poorly understood. To enhance understanding of these key concepts, the objectives of this study are to determine how perception of pedestrian safety at unsignalized crosswalks differs from perception of comfort, and the relationship of each with perception of yielding. A generalized structural equations model is developed using data from an online survey in which 366 participants (i.e., “perceivers”) rated yielding, safety, and comfort for sample videos of pedestrian interactions with motor vehicles and bicycles. Results show that an individual’s perception of yielding plays a crucial role in mediating the effects of interaction attributes (e.g., vehicle speed, proximity) and perceiver attributes (e.g., travel habits) on their perceptions of pedestrian safety and comfort. For example, people who bicycle more frequently perceive pedestrians as more comfortable than people who walk more frequently, rooted in misalignment on what constitutes adequate yielding. Strategies to address pedestrian comfort can focus on a set of key yielding behaviors by drivers and cyclists – particularly allowing the pedestrian to cross first. Motor vehicle drivers must exhibit stronger yielding behavior (e.g., allow a larger time gap) than bicycles to achieve the same level of perceived pedestrian safety and comfort. Although perceptions of safety and comfort are strongly related and similarly impacted by yielding, researchers should be cautious about using the concepts interchangeably because they are differently impacted by attributes of the interaction and perceiver.     

The safety and conspicuity of pedestrian crossing at roundabouts: The effect of median refuge island and zebra markings

Roundabouts are one of the most used road intersections because, compared to signalized ones, they reduce conflict points between traffic flows and moderate driving speed. Great attention should also be paid to vulnerable road users at roundabouts. According to accident statistics, in fact, accessibility of pedestrians and cyclists is not always ensured.This paper has evaluated the effects on the visibility of pedestrian crossing before and after the displacement of zebra markings, moved before intersections, and the introduction of media refuge islands and “Yield here to pedestrians” vertical signs. The above effects have been assessed by before-after analysis of speed and visual behaviour of drivers approaching the crosswalk.Moreover, the analysis of the drivers’ eye movements has highlighted the most salient elements of the pedestrian crossing. The relation between the drivers’ visual behaviour and the vehicle speed have also been calculated. Results have confirmed that the intervention carried out has increased both visibility and safety of the studied pedestrian crosswalks.Zebra markings and the median refuge island have turned out to be the most glanced elements, respectively seen by 93.75% and 56.25% of the drivers, followed by the “Yield here to pedestrians” vertical sign. The mean distance of first fixation of the crosswalk increased from 21.98 m before the intervention, to 40.69 m after it. The drivers perceived the pedestrian crossings from a longer distance after the intervention, and they continued to glance at the crosswalk while approaching it, enhancing their visual attention.     

Investigating the effectiveness of perceptual treatments on a crest vertical curve: A driving simulator study

Rural roads are characterized by a high percentage of run-off-the-road accidents and head-on collisions, mainly caused by inappropriate speeds and failure to maintain a proper lateral position along the roadway alignment. Among several road safety treatments, low-cost perceptual measures are considered an effective tool, as they generally increase the risk perceived by drivers, or even alter the drivers’ speed perception, and consequently tempting them to decrease their speeds. Their effectiveness has been widely recognized in a number of studies, especially with respect to road intersections and curves.The overall aim of this study is to investigate the effects of different perceptual treatments on driving speed, along a crest vertical curve of an existing two-lane rural road, in order to identify the most effective measure to reduce speed and define its subsequent implementation in the field. Three perceptual treatments were tested using a driving simulator: white peripheral transverse bars, red peripheral transverse bars and optical speed bars, with each one being painted along the approaching tangent to the crest vertical curve. The effects of these speed-reducing measures were investigated using a sample of forty-four participants, by comparing the driving speeds with those recorded under a baseline condition (without a treatment); these were also used to validate the driving simulator’s speed measurements with those found in the field. Moreover, subjective measures were collected, consisting of the driver’s static evaluation of the desired speed, risk perception and markings comprehension, based on screen shot pictures that represented the simulated configurations of the treatments.The findings demonstrated an overall effectiveness of the perceptual treatments, although only the red peripheral transverse bars were found to significantly reduce the driving speeds (−6 km/h). The analysis of the questionnaire yielded interesting information and demonstrated the importance of performing driving simulation tests for evaluating the effectiveness of perceptual treatments.Finally, the results confirmed the enormous potential of using driving simulators to pinpoint a number of speed-reducing measures, and consequently select the most effective one that reduces cost and promotes safety before its actual implementation in the field.     

Do drivers differ in their attitudes on speed limit compliance between work and private settings? Results from a group of Nigerian drivers

Existing evidence suggests that drivers, particularly those who work in companies with strong road safety cultures exhibit different sets of speeding attitudes and behaviours in work and private driving. Using Ajzen and Fishbein’s (1980) Theory of Planned behaviour (TPB) and on-road driving experiments, this study examined the self-reported and objective behaviour of driving within posted speed limits for a sample of fleet drivers. The findings show that the TPB explained up to 24% of the variance in intention to comply with speed limits. Drivers’ attitude emerged as the most significant predictor and strongest correlate with intentions to comply with the speed limit in both work and private vehicle.Further analysis revealed participants had a higher intention to comply with speed limits in their work than private vehicle. Also, investigation of the relationship between TPB variables and observed speeding behaviour suggests that participants with higher intention to comply with the speed limit or high perceived behavioural control (PBC), exceeded the speed limit less often than those with lower intention to comply with the speed limit or low PBC. The findings have important theoretical and applied implications for development of better speed limit compliance interventions to improve driving behaviour, and road safety in general.     

Aging drivers and post delineated express lanes: Threading the needle at 70 miles per hour

Post-delineated express lanes represent a combination of driving complexities that are particularly difficult for older drivers to navigate. The narrow geometry and high speeds that are common to this treatment reflect a critical test for drivers whose depth perception, contrast sensitivity, and visual processing speed are reduced. The present study was designed to empirically examine the effects of age and color of express lane delineators on driver behavior. Three groups of participants (aged 18–39, 40–64, and 65 + years old) were required to complete a series of simulated driving scenarios consisting of combinations of single and dual lane configurations, with speed and lane position measured at the beginning and midpoint of each express lane. All drivers were pre-screened on various visual functioning abilities. Drivers in the 65 and older group show significant age-related declines in depth perception, contrast sensitivity, and phoria which were subsequently correlated with a wide range of driving measures including deceleration rate, brake time, jerk, speed, and lane position. Age related perceptual declines were statistically correlated with slower driving speed and wider lane deviations, including a statistically significant increase in the number of excursions beyond the typical 12-foot lane width. Based on these findings, the behavior of senior drivers was identified as a distinct design condition that should govern the design of high-speed, narrow geometric conditions. This age group requires wider lane widths, particularly at the beginning of single-lane post delimited sections, wider buffer areas around the post markers, and dual lane configurations wherever possible.     

Drivers’ and cyclists’ safety perceptions in overtaking maneuvers

Drivers overtaking cyclists on rural roads are a safety concern, as drivers need to handle the interaction with the cyclist and possibly an oncoming vehicle. Improving the maneuver’s outcome requires an understanding of not only the objective, measurable safety metrics, but also the subjective, perceived safety of each road user. Previous research has shown that the perceived safety of the cyclist is most at risk at the passing moment, when driver and cyclist are closest to each other. However, to develop safety measures, it is necessary to know how both road users perceive safety, by understanding the factors that influence their perceptions during the overtaking maneuver. This study measured the perceived safety of drivers in a test-track experiment in Sweden and the perceived safety of cyclists in a field test in Spain. For both drivers and cyclists, we developed Bayesian ordinal logistic regression models of perceived safety scores that take as input objective safety metrics representing the different crash risks at the passing moment. Our results show that while drivers’ perceived safety decreases when there is an oncoming vehicle with a low time-to-collision, cyclists’ perceived safety is reduced by a small lateral clearance and a high overtaking speed. Although our datasets are heterogeneous and limited, our results are in line with previous research. In addition, the Bayesian models presented in this paper are novel and may be improved in future studies once more naturalistic data become available. We discuss how our models may support infrastructure development and regulation, policymaking, driver coaching, the development of active safety systems, and automated driving by providing a possible method for predicting perceived safety.     

Diverging diamond interchanges: A driving simulator study

This study assessed driver performance while navigating a Diverging Diamond Interchange (DDI) compared to a standard intersection in a driving simulator. A total of 201 Western Australian (WA) drivers aged 18–80 years completed the simulator drive and questionnaire. Measures of driving simulator performance assessed included time spent out of lane, number of lane excursions, compliance to the speed limit, crashes and near misses. Other driving measures, which were recorded by the researcher, included driver errors/violations such as red-light violations, wrong way violations and navigation errors. Qualitative information was also obtained in a post exit interview with each participant regarding the difficulties they experienced when driving through the DDI. A repeated-measure analysis of variance (r-ANOVA) was undertaken to examine differences in intersection type (DDI versus standard intersection) and driving performance measures from the driving simulator. The only significant result was compliance to the speed limit (F (1, 656) = 160.11, p < 0.001) on the driving simulator. A higher proportion of red-light violations were observed by the researcher as participants navigated through the DDI, compared to the standard intersection. Qualitative comments from participants also highlighted the need for better signage and road markings. Recommendations when DDIs are implemented include community education on speed limit compliance, avoidance of red-light violations and design improvements regarding signage and road markings.     

An examination of the influence of crosswalk marking removal on pedestrian safety as reflected in road user behaviours

In some local authorities in Israel, road markings were removed from non-signalised crosswalks situated on multilane divided urban roads. This study examined whether this treatment contributes to pedestrian safety, based on the analysis of differences in road user behaviours and pedestrian crossing conditions at sites without crosswalk markings (treatment sites) versus those with the markings (comparison sites). Field observations were conducted at two treatment and four comparison sites, including video-recordings and free-flow speed measurements. The speed data analysis indicated that treatment sites were associated with higher speeds as compared to other sites, at least in one travel direction, and that speed values were sufficiently high to create a threat of severe injury for the crossing pedestrians. Examinations of other road user behaviours showed that treatment sites are associated with higher obedience of pedestrians to safe crossing rules and low rates of pedestrian-vehicle conflicts during the crossing, but also with long waiting times by pedestrians prior to crossing, low rates of giving-way to pedestrians and more vehicles ignoring pedestrian needs to cross. In general, pedestrian crosswalk removal brought about a worsening in the possibility of crossing the road for pedestrians that in combination with high vehicle speeds cannot be recognised as a safety-improving measure. The study did not support the claim that removing a marked crosswalk leads to safety benefits for pedestrians.     

Young drivers’ perception of hazards: Variation with experience and day versus night

Young novice drivers have a relatively high crash risk for several years following initial licensing, and while all drivers are at greater risk at night, the night-time increase is greater for inexperienced drivers. Poor hazard perception has been identified as an important contributor to inexperienced drivers’ risk, but research on day-night differences in hazard perception for drivers varying in experience is lacking. This exploratory study investigated the nature of hazards reported by young inexperienced drivers versus more experienced and slightly older drivers. Hazards were not pre-identified by researchers; participants were simply provided with a general definition of ‘hazard’. Analysis focused on how experience level affected qualitative differences in the kinds of hazards reported, with particular focus on day-night differences.The 53 participants ranged in driving experience from learners through to 5+years post licensing, and in age from 16 to 30 years. They viewed 14 day- and night-time video clips of a diverse range of driving situations, pausing the video whenever they identified a hazard and then explaining why they had paused it at that point. Their responses were recorded. Content analysis of responses showed that more experienced drivers reported visibility-related hazards significantly more often than inexperienced ones, and significantly more so at night. They also commented significantly more on hazards related to tight bends in the road and significantly less on hazards concerning compliance with rules. Comments tended to be fewer with higher vehicle speeds, particularly for the least experienced drivers.Results are discussed in terms of how experience-related differences in drivers’ cognitive schemata and mental models are likely to affect hazard perception and crash risk, particularly at night. Some implications for driver training and license testing are suggested.     

The Effect of Perceived Control on Risk Taking1

The experiment investigates the effect of perceived control on risk taking in a dynamic, everyday task. Using established and validated video simulation techniques, the risk-taking preferences for 96 drivers were measured for a range of driving activities (speed choice, following distance, gap acceptance, and overtaking). The perceived control manipulation was as follows: Half of the participants were told to imagine they were driving the vehicle, and the other half were told to imagine they were passengers. Those who were told to imagine they were driving chose significantly faster speeds than did those who were told to imagine they were passengers. Differences for the other risk-taking measures were not significant. For speed choice, it could be argued that an illusion of control was in operation, such that those who were in control (i.e., drivers) were comfortable with a higher level of risk than those who were not in control (i.e., passengers).     

Cross-cultural effects on detecting multiple sources of driving hazard: Evidence from the deceleration detection flicker test

Collision rates in Malaysia are much higher than the UK; do these reflect poorer hazard perception skill or does exposure to hazardous events improve hazard detection ability? The deceleration detection flicker test (DDFT) was used to investigate the effect of experience and cross-cultural differences between Malaysian and UK drivers in their ability to detect the deceleration of a lead vehicle while simultaneously identifying any secondary hazards in side roads. Matched groups of participants with lower or higher levels of experience were recruited from the University of Nottingham in the UK and Malaysia. Malaysian drivers were significantly less accurate than UK drivers in detecting the deceleration of lead vehicles on urban roads, and significantly less accurate in detecting the presence of secondary hazards across all road types. Experienced drivers were significantly faster than novices in detecting decelerations of the lead vehicle, and were significantly more accurate in detecting the presence of secondary hazards. The study concludes that high exposure to hazardous events on the road in Malaysia does not yield expertise in this hazard perception task, although the DDFT does differentiate experience cross-culturally.     

Predicting pedestrians’ intention to cross the road in front of automated vehicles in risky situations

Due to the absence of a human driver, the introduction of fully automated vehicles (FAVs) may bring new safety challenges to the traffic system, especially when FAVs interact with vulnerable road users such as pedestrians. To ensure safer interactions between pedestrians and FAVs, this questionnaire-based study aims to understand Australian pedestrians’ intention to engage in risky road-crossing behaviors when they interact with FAVs vs. human-driven vehicles (HDVs). A 2 × 2 between-subject design was utilized, in which two risky road-crossing scenarios were designed and took into account the vehicle type (FAV vs. HDV) and vehicle speed (30 km/h vs. 50 km/h). A total of 493 participants (aged 18–77) were randomly assigned to one of the four experimental conditions and completed an online questionnaire based on the extended Theory of Planned Behavior (TPB). This questionnaire measured pedestrians’ intentions to cross the road in the assigned scenarios as well as the motivational factors behind these intentions in terms of attitude, subjective norm, perceived behavioral control, perceived risk and trust in the vehicle. The results show that pedestrians had significantly higher intentions to cross the road in front of approaching FAVs than HDVs. Participants also reported a lower risk perception of crossing in front of FAVs and greater trust in this type of vehicle. Attitude, subjective norm, and perceived behavioral control were significant predictors of intentions to engage in risky road-crossing behavior. Findings of this study provide important implications for the development and implementation of FAVs in the future road transport system.     

Effects of position of speed limit signs and the presence of speed camera on Malaysian drivers’ speed choice: An eye-tracking study

Speeding is one of the most common driving violations in the world including in Malaysia. Reducing speed-related fatalities is one of Malaysia’s strategies to improve road safety. The current study aimed to investigate the effect of speed limit sign positioning and the presence of speed camera on drivers’ judgments about the appropriate speed to drive and their associated eye movements. Twenty participants took part in the study, and thirty two images of roads with a range of actual speed limits were presented. In each picture the displayed speed limit was edited to 30% lower than what participants think is appropriate on average. Speed limit signs were either presented on the road or on the speed limit sign boards at the road sides, and a speed camera sign was either present or not. Drivers judged a lower appropriate speed to drive when the camera sign was present than absent, while there was a wider spread of differences between judged and displayed speed when the speed limit sign was presented on the board than on the road. Drivers were quicker in fixating and looked more at the general area in which the speed limit sign appeared. Therefore drivers’ visual attention across scenes may be manipulated by the sign positions. These low-cost interventions could be useful in managing speed choice in Malaysia.     

How fast would you (or should you) drive here? Investigation of relationships between official speed limit,perceived speed limit,and preferred speed

Speed is a critical risk factor, which makes its management the central point of the Vision Zero approach. Driving speed is influenced by speed choice, and in turn by the perception of the road parameters, as well as by the characteristics of drivers. Credible speed limits and self-explaining roads have been suggested as promising countermeasures; however, these rather theoretical concepts have only rarely been operationalized and quantified.The aim of this study was to investigate the relationships between speed indicators (official speed limit, perceived speed limit, preferred speed), as well as their differences, and to determine which road and personality characteristics influence them. Compared to previous studies, we introduced several innovative features, including a richer personality dataset based on three different questionnaires, a focus on all three types of roads (urban, rural, transition), and representative data on observed speeds.Using statistical models of the speed indicators, we found that both speed limit belief and speed choice, as well as their differences, are often influenced by the same characteristics. These are mainly more generous road design (higher road class, higher speed limit, and wider road) and the presence of additional elements (vegetation, pavements, and pedestrian crossings). These characteristics may help improve the credibility of speed limits and self-explaining performance.     

Situation Awareness: Its proficiency amongst older and younger drivers,and its usefulness for perceiving hazards

The two studies reported here sought to measure and compare the Situation Awareness (SA) of younger and older driver groups whilst driving (Study 1), and watching video footage of actual car journeys (Study 2). In both studies this was achieved by recording a participant’s commentary on what s/he felt was of relevance to the driving task. The narratives produced were analysed by computer software that could abstract main concepts and calculate scores indicative of Situation Awareness. In Study 2, these scores were related to others for hazard perception proficiency (also derived from participant commentaries). It was found that the older drivers matched and often exceeded the younger drivers when their SA scores were compared individually, but not when assessed as a group. However, the younger drivers out-performed their older counterparts in hazard perception ability, and this was shown to be related to their Situation Awareness score. When the results from participants who undertook both studies were compared, it was found that Situation Awareness performance was significantly higher when commenting on video footage (Study 2) than whilst actually driving (Study 1).     

Effects of reduced contrast on the perception and control of speed when driving

Misperception of speed under low-contrast conditions has been identified as a possible contributor to motor vehicle crashes in fog. To test this hypothesis, we investigated the effects of reduced contrast on drivers' perception and control of speed while driving under real-world conditions. Fourteen participants drove around a 2.85 km closed road course under three visual conditions: clear view and with two levels of reduced contrast created by diffusing filters on the windscreen and side windows. Three dependent measures were obtained, without view of the speedometer, on separate laps around the road course: verbal estimates of speed; adjustment of speed to instructed levels (25 to 70 km h(-1)); and estimation of minimum stopping distance. The results showed that drivers traveled more slowly under low-contrast conditions. Reduced contrast had little or no effect on either verbal judgments of speed or estimates of minimum stopping distance. Speed adjustments were significantly slower under low-contrast than clear conditions, indicating that, contrary to studies of object motion, drivers perceived themselves to be traveling faster under conditions of reduced contrast. Under real-world driving conditions, drivers' ability to perceive and control their speed was not adversely affected by large variations in the contrast of their surroundings. These findings suggest that perceptions of self-motion and object motion involve neural processes that are differentially affected by variations in stimulus contrast as encountered in fog.     

Instruction-prompted objective behaviors as proxy for subjective measures in a driving simulator

Interactions with other road users and interpretations of traffic situations are important aspects of driving safety. Self-reports are often used to study drivers’ perceptions and attitudes but self-reports can be inaccurate and biased because of socially desirable responding. Driving simulators offer objective measures of driver behaviors but have limited ability to elicit natural behaviors. To address this issue, we tested a driving simulator-based approach that combined realistic driving scenarios including potentially frustrating forward obstacles and delays in travel time with two different types of instructions. Participants' vehicle control behaviors and subjective perception of traffic delays were compared. Results demonstrated that behaviors collected following instructions to drive safely did not have significant associations with participants’ perceptions of the traffic delays while participants following instructions to drive quickly demonstrated behaviors that were predictive of their subjective perceptions of the traffic delays. The findings suggest that vehicle control behaviors can be used as a proxy for subjective perceptions of traffic delays. We conclude that driving simulator methodology combining instructions, realistic traffic scenarios, and adaptive analytical methods is appropriate for studying drivers’ behaviors and interactions with other road users and can minimize the need to rely on subjective self-reports.     

External communication of automated vehicles in mixed traffic: Addressing the right human interaction partner in multi-agent simulation

The urban traffic system is most likely to change in the next years to a mixed traffic with human drivers, vulnerable road users, and automated vehicles. In the past, the development of external communication approaches for automated vehicles focused on scenarios where an automated vehicle communicates with either a pedestrian or a human driver. However, interactions with more than one traffic partner are more realistic. Therefore, a study with 42 participants was conducted with a multi-agent simulation in which an automated vehicle interacted simultaneously with two participants, a pedestrian and a driver of a manual vehicle. In this study, two main scenarios were investigated in order to evaluate the safety and efficiency of the interactions and to determine whether the human road users feel correctly addressed. In one scenario, the pedestrian had to cross the road in front of the automated and the manual vehicle, which were approaching from different sides. In the other, the manual vehicle had to drive through a bottleneck in front of the oncoming automated vehicle, while the pedestrian had to cross the road after both vehicles passed. The communication approach of the automated vehicle consisted of implicit signals using a speed profile and lateral offset within its lane, and explicit signals using an external human–machine interface. The results of the study show that no collisions were observed in terms of safety and no significant negative effects on efficiency were measured. However, in contrast to single agent interactions, a majority of participants felt wrongly addressed in situations where the automated vehicle signals the right-of-way to the other human road user. It can be concluded that the communication approach of the automated vehicle needs to be modified in order to address certain road users more clearly.