Approaching intersections: Gaze behavior of drivers depending on traffic,intersection type,driving maneuver,and secondary task involvement

Urban intersections are hotspots for crashes because they provide a location for several traffic streams and types of road users to cross. A main cause of crashes is the misinformation of drivers as they fail to sense relevant visual information. We aimed to analyze the gaze behavior of car drivers in a variety of intersection scenarios, bringing together the partial findings of previous research, and examine the interdependencies of the contributing factors to provide a database for driver modeling. In a driving simulator study with 59 participants, we varied intersection scenarios regarding drivers’ right of way (yield sign, green traffic light), intersection type (T junction, X intersection), surrounding traffic (none, irrelevant, relevant), and intended driving maneuver (left turn, right turn, going straight). A total of 25 intersection scenarios were presented in a within-subjects design to a control group and a group with a cognitive load task (counting back in numbers of two). Fixations were coded regarding defined areas of interest in the field of view and separated according to three segments of the intersection approach: 75–50 m, 50–25 m, and 25–0 m before entering the intersection. The results show that the effect of surrounding traffic, secondary task engagement, and the intended driving maneuver changed dramatically depending on the right of way of the driver. Surrounding traffic primarily affected gaze behavior in scenarios of ceding the right of way close to the intersection entry. The cognitive load task increased fixations on the road center especially in situations where the driver had the right of way, but less in situations of ceding the right of way. Interactions with the type of intersection were only apparent for different driving maneuvers. This study provides a detailed and comprehensive picture of drivers’ attentional processes when approaching intersections which is relevant for understanding and modeling of driver behavior in urban traffic.     

Impact of “Signal Ahead” pavement marking on driver behavior at signalized intersections

When drivers are approaching a signalized intersection at the onset of yellow signal, they may hesitate to decide whether to stop or cross the intersection due to the dilemma zone. As defined in the Traffic Engineering Handbook [Institute of Transportation Engineers (ITE). (1999). Traffic engineering handbook, Washington, DC: Institute of Transportation Engineers], the dilemma zone for an intersection is a specific road segment, prior to the intersection in which a vehicle approaching the intersection during the yellow phase can neither safely clear the intersection, nor stop comfortably at the stop line. In this study, a pavement marking countermeasure is proposed to reduce the dilemma zone and improve traffic safety at signalized intersections. A pavement marking with word message ‘Signal Ahead’ that is placed on the pavement upstream of a signalized intersection may have a potential to assist drivers in stop/go decisions and improve driver performance during the signal change. This paper presents a simulator-based study that was designed to test the impact of the pavement marking countermeasure on driving behaviors, including driver’s stop/go decision, red-light running violation, brake response time, and deceleration rate of the stopping vehicle. The experiment results indicated that the marking had positive effects on drivers’ behaviors at signalized intersections. It was found that the marking can reduce the probabilities of both conservative-stop and risky-go decisions, contribute to a lower red-light running rate, and result in a lower deceleration rate for stopping drivers at higher speed limit intersections. These findings suggest that the marking countermeasure may have a potential to reduce the probabilities of both rear-end and angle crashes.     

Increasing motorist compliance and caution at stop signs.

This study evaluated strategies to improve motorist compliance and caution at three stop‐sign‐controlled intersections with a history of motor vehicle crashes. The primary intervention was a light‐emitting diode (LED) sign that featured animated eyes scanning left and right to prompt drivers to look left and right for approaching traffic. Data were scored from videotape on the percentage of drivers coming to a complete stop and the percentage of drivers looking right before entering the intersection. Observational data were collected on the percentage of right‐angle conflicts (defined as braking suddenly or swerving from the path to avoid an intersection crash). The introduction of the LED sign according to a multiple baseline across the three intersections was associated with an increase in the percentage of vehicles coming to a complete stop at all three intersections and a small increase in the percentage of drivers looking right before entering the intersections. Conflicts between vehicles on the major and minor road were also reduced following the introduction of the animated eyes prompt.     

Drivers’ visual attention: A field study at intersections

Crossing a road intersection, a driver must collect visual information from various locations. The allocation of visual attention, which allows this collection, mainly relies on top-down processes. This study focuses on three top-down factors which influence the collection of visual information: the value of visual information for the ongoing task, their bandwidth, and the familiarity with the environment. These factors are studied according to the priority rules at intersections (Give way, Stop or Priority), the expected traffic density (Lower or Higher) and the number of passages (First or Second passage). Fourteen participants were installed in an instrumented vehicle equipped with an eye-tracker. They drove during 1h45 along a 80-km long route, mainly on rural roads, which included 19 intersections. Visual attention was studied by means of the head and gaze horizontal eccentricity. Effects were found for each of the three factors, in agreement with Wickens’ theoretical framework and with previous studies, despite the important variability in the data due to the experimental situation.     

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.     

Effects of variable message signs for slippery road conditions on driving speed and headways

This field study investigated the effects of two variable message signs (VMS) on driver behaviour. Specifically, the signs were a warning sign for slippery road conditions and a minimum headway sign. The study was performed as a before-and-after experiment at three test sites in Finland with an after period covering two winter seasons. The results showed that the slippery road condition sign reduced the mean speed on slippery roads by 1–2 km/h in addition to the decrease caused by the adverse road conditions. The minimum headway sign decreased the proportion of headways shorter than 1.5 s for cars in car-following situations, in addition to a speed reduction of 1 km/h. The effects were somewhat smaller during the second winter than the first.     

Larger size vehicles (LSVs) contribution to red light running,based on a driving simulator experiment

Larger size vehicles (LSVs), comprising semis and six-wheelers drive higher and wider than passenger cars which could affect the visibility of traffic lights for the following passenger car driver at signalized intersections. This paper investigates the contribution of LSVs to red light running resulting from vertical visibility blockage based on a driving simulator experiment. Three sub-scenarios were developed in the driving simulator. The first sub-scenario served as a base sub-scenario, where the simulator car follows a passenger car. The second sub-scenario served as the test sub-scenario, where the simulator car tracks an LSV. The results obtained by comparing the sub-scenarios confirmed that LSVs generate higher red light running rate at signalized intersections due to vertical visibility blockage. The third sub-scenario (or suggested solution sub-scenario) tested a suggested solution by the Federal Highway Administration for the vertical visibility blockage issue, which consists of installing an additional signal pole on the right side of the road. The comparison between the test sub-scenario and the suggested solution sub-scenario demonstrated that the addition of a signal pole on the right side of the road decreases red light running resulting from vertical visibility blockage significantly.     

When norms turn perverse: Contextual irrationality vs. rational traffic violations

A perfectly adequate traffic rule can turn “perverse” in situations when it does little to enhance road safety but seems – at least in the drivers’ minds – directed primarily at punishing those who violate it. This study examined traffic rule obedience in situations in which the rule was not in accordance with real safety needs. Six rules with major impact on road safety were analyzed: waiting at red traffic lights, legal overtaking, obeying the 50 km/h speed limit, wearing seatbelts, legal stopping/parking, and driving the car in good technical condition. Participants evaluated how adequate these rules are for safety. Then they were faced with six scenarios, that made each of these rules appear irrational, and were asked to report their potential engagement in deviant behavior. The survey data were collected in a sample of 605 drivers. Multiple regression analyses showed that in most situations rule violation depended on the usual deviant behavior, perceived irrationality of the rule, little respect for the law and low risk perception. These factors best explained the 50 km/h speed limit violation. The results suggest that the lack of situational risk factors, which makes the rule look meaningless, is important determinant of rule violation. Implications for massive disobedience and road safety are discussed.     

Gaze behavior when approaching an intersection: Dwell time distribution and comparison with a quantitative prediction

The allocation of overt visual attention is investigated in a multi-task and dynamical situation: driving. The Expectancy–Value model of attention allocation stipulates that visual exploration depends on the expectancy and the value of the task-related information available in each Area Of Interest (AOI). We consider the approach to an intersection as a multi-task situation where two subtasks are involved: vehicle control and interactions with other drivers. Each of these subtasks is associated with some specific visual information present in the associated AOIs: the driver’s lane and the intersecting road at the intersection. An experiment was conducted in a driving simulator, coupled with a head-mounted eye-tracker. The intersecting road’s AOI’s Expectancy was manipulated with the traffic density, and its Value was manipulated with the priority rule before the intersection (stop, yield, and priority). The distribution of visual attention and the dynamics of visual exploration were analyzed on 20 participants, taking into account the dwell time in the AOIs associated to the driving subtasks, and the gaze transitions between the AOIs. The results suggest that visual attention to intersecting roads varied with the priority rule, and impacted the visual attention associated with the vehicle control subtask. In addition, a quantitative model was used to improve the understanding of the Expectancy and Value factors. The comparison of the data with the model’s predictions enables quantifying the observed differences between the experimental factors. Finally, the results associated with the traffic density are discussed in relation to the nature of the relevant information while approaching the intersection.     

Field study on the behavior of right-turning vehicles in Malaysia and their contribution on the safety of unsignalized intersections

Behavior of right turning vehicles in the context of safety is characterized by their use of turning indicators and compliance with the stop rule. They are influence by the width of the carriageway and the variation in volume on the major road with respect to the traffic moving in the near and far side direction. Other factors affecting the behavior are the speed and spacing between vehicles moving on the major road. Lack of adequate past knowledge on the effect of geometric variation in terms of road width and directional variation in volume on the safety of unsignalized intersections have provided the motivation for this study. This paper focuses on the many factors that affect the behavior of right-turning vehicles resulting into conflicts. A brief account of the unique indigenous maneuver termed as the “Weaving Merging Right Turn” (WMRT) is provided and its effectiveness with respect to conventional right turn is evaluated. Data of 39,016 vehicles collected on 10 sites between January and June 2014 was analyzed. Multiple accidents were observed only on sites which had near side traffic volume greater than far side traffic volume. This result remains consistent with sites having single as well as multiple lanes per direction on the major roads. The number of conflicts for vehicles performing the WMRT was 2.5 times less as compared to the conventional right turn. Moreover WMRT was found to be the maneuver of choice for right turning motorcyclists with 60% of them opting for it over the conventional right turn on intersections having major road width less than 9 m. None of the motorcyclists, which were involved in a traffic conflict, were observed to use their turning indicator. Moreover none of the motorcyclists, which experienced a traffic conflict, were found to comply with the stopping rule at sites with major road width less than 9 m. On sites with major road width greater than 9 m, 45% of motorcyclists, involved in a traffic conflict, complied with the stopping rule as compared to 79% by vehicles other than motorcycles.     

Yielding behavior and traffic conflicts at cyclist crossing facilities on channelized right-turn lanes

Channelized right-turn lanes (CRTLs) improve traffic flow efficiency, enabling right-turning drivers to bypass traffic lights at signalised intersections (for right-hand drive countries). Many CRTLs provide crossing facilities for pedestrians and cyclists. Previous studies examining the safety performance of CRTLs indicate that they increase overall safety levels but hint that safety issues regarding vulnerable road users exist. This study investigated these issues through site-based observations of yielding behavior and evaluated the effect of the priority rule on cyclists’ safety in two CRTL designs. Four locations in Belgium were selected for video observations: two where the priority rule favoured cyclists and two where motorists had priority.With regard to yielding, four types of crossing behavior were identified and defined. Independent of the priority rule, cyclists crossed the conflict zone first in most interactions without taking the initiative to cross first. Underlying reasons for motorists willingly giving away their right-of-way could not be determined, but possible courtesy or fear of inflicting injuries at vulnerable road users might be at hand. A safety evaluation was performed using two traffic conflict indicators (TTC_min and the TA value). High correlations between the two indicators were found (r² > 0.83), but no conclusions about the safest priority rule for cyclists could be drawn. The results hinted, however, that locations with motorist priority and cyclists crossings from right to left (from the driver’s point of view) yields the highest proportion of safety critical events.     

Is there a spillover effect of a right turn on red permission for bicyclists?

A number of countries allow bicyclists to perform a right turn on red (RTOR) at some specific intersections to promote cycling by reducing the required physical effort and trip time. Implementation of a rule that allows a RTOR for bicyclists at some intersections could lead not only to local effects at those intersections where the rule actually applies, but also to supralocal effects. Using an experimental survey approach, this study explores whether a so-called ‘spillover effect’ of the rule can be expected. This effect would imply that allowing bicyclists to turn right on red at some intersections causes them to also turn right on red more often at intersections where RTOR for bicyclists is not allowed.The answers from 768 respondents indicate that respondents with a high awareness of the existence of a RTOR rule for bicyclists (experimental group) turn right on red significantly more often at intersections where RTOR for bicyclists is not permitted than respondents with a low awareness of the rule (control group). This indicates that implementation of the RTOR rule for bicyclists can indeed lead to an increase in red light running at other intersections. This might lead to safety issues at intersections where RTOR for bicyclists is not permitted, since road authorities could have decided not to allow RTOR for bicyclists at these intersections for safety reasons.The study also finds that men, young people and people who generally perform more risky cycling behaviours have a higher tendency to perform non-permitted RTOR. These findings are in line with existing literature.     

Do familiarity and expectations change perception? Drivers’ glances and response to changes

The present study shows that repeated exposure to a road environment changes eye movement behaviour. In addition, repeated exposure may result in inadequate responses to unexpected changes in the road environment. Participants drove a low-cost simulator while their eye movements were recorded. With repeated exposure participants’ glances at traffic signs along the route were shorter while having a better recollection of the traffic signs along the route. At the last drive, the priority situation at an intersection was changed (a priority road was changed into a yield situation). Even though drivers glanced at the sign that indicated the new priority situation, they did not sufficiently process the information to show an adequate response. Only two out of 12 drivers showed any response, being a response only after crossing the priority road markings. The current finding that unexpected but relevant information may be missed by drivers is relevant for other monitoring tasks.     

Attitudes,risk perception and risk-taking behaviour among regular cyclists in Norway

The main aim of the study was to investigate whether attitudes toward traffic safety, risk perception, worry, risk tolerance, safety priority, and accident involvement are associated with cyclists’ risk-taking behaviour. Two types of cyclists’ risk-taking behaviour were studied: (1) ‘violation of traffic rules, and (2) ‘conflicts with other road users when cycling’. The study was based on a questionnaire survey carried out in 2017 among regular cyclists in Norway (n = 426). The results revealed that cyclists’ risk-taking behaviour was influenced by their attitudes, risk perception, and accident involvement. Pragmatic attitudes toward traffic rule violations and safety priority were found to be important predictors of the frequency of rule violations when cycling. Attitudes towards the enforcement of traffic rules for cyclists and dissatisfaction with the traffic rules for cyclists were found to be important predictors for the frequency of situations involving conflicts with other road users. Risk perception and accident involvement were found to be associated with conflicts with other road users, but not with rule violations when cycling. The findings show that risk perception and attitudes toward traffic safety are important for cyclists’ risk-taking behaviour in traffic. The road infrastructure and the traffic regulations are primarily planned for car drivers and pedestrians. If cyclists’ attitudes are to be changed, the cycling infrastructure and traffic rules for cyclists would need to be adjusted to cyclists as road users. When building new infrastructure and implementing new safety measures for cyclists, it is important to include attitude campaigns, as well as communications to the public about safety and the risks linked to cycling. Attitude campaigns could be used to strengthen the authorities’ communications that cyclists are prioritized as road users.     

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.     

Road signs depicting childrens's book illustrations temporarily reduce speed on urban roads

Speeding on urban roads is a major road safety problem. Police enforcement and speed humps are effective measures to prevent drivers from speeding. However, these measures may also elicit none compliance because of their restrictive nature. Therefore, non-compulsive measures that nudge drivers to adopt low speeds are also required. One such a nudge was evaluated: road signs displaying children’s book illustrations. These signs display illustrations which were created by the late illustrator and writer of books for toddlers, Dick Bruna, and are named ‘Dick Bruna signs’. The idea of the developers of these signs was that they will evoke feelings of caution and care in drivers and this will make them drive slower. To evaluate the effect, two studies were conducted. In the first study participants watched photos from the driver’s perspective. They had to report how fast they expected others would drive and how fast they themselves would drive. Participants reported speeds of others higher than their own speeds but the pattern was the same: speeds on photos with a Dick Bruna sign were approximately 4 km/h lower than on the same photos without a Dick Bruna sign and speeds were not significantly lower when a neutral sign such as an advertisement was visible. In the second study speeds were measured during seven consecutive weeks on five experimental roads and five comparison roads. On the experimental roads, during the week 3–5 a Dick Bruna sign was placed. Controlled for developments in speed on the comparison roads in the same period, mean speed was marginally significant lower, and the V85 speed and the proportion of speed offenders were significantly lower in only the first week after placement of the signs.     

Effects of a driver assistance system with foresighted deceleration control on the driving performance of elderly and younger drivers

It is imperative to enhance the safety of elderly individuals on the roads to ensure the quality of their daily life. Near-miss incidents or accidents at blind intersections often result from a conflict between the behaviors of the driver and of other road users (pedestrians and cyclists). The failure to search for potential conflict in the context of blind intersections is a concern pertaining to road safety. The proposed assistance system performs a proactive braking intervention to achieve a referenced velocity in uncertain situations, such as one in which an unobserved pedestrian might initiate a road crossing. The proactive braking intervention attempts to manage the potential risk of crashing with respect to covert hazards. Because an automated system may impair a human’s ability to perceive and respond to hazardous situations while driving, this study was designed to examine the effects of proactive braking intervention and visual support cues on elderly and younger drivers’ ability to respond to information about potentially hazardous situations. We conducted a public-road driving experiment involving 108 elderly and younger drivers from two non-overlapping age groups. It was observed that the vehicle slowdown realized through the proactive braking intervention enabled the drivers to perform safety confirmation near blind spots and caused them to be more sensitive to and wary of potential hazards. This approach could be effective not only for elderly drivers, but also for young or inexperienced ones.     

Cyclist efficiency and its dependence on infrastructure and usual speed

Bicyclists are a heterogeneous group, with varying abilities, traffic education and experience. While efficiency was identified as an important factor on utility bicycle trips, it might be traded for experienced safety, for example by choosing different pathways in a given situation, or by relinquishing one’s right of way. In a semi-controlled study with 41 participants, a grouping was made according to self-reported riding speed in relation to other cyclists. The participants cycled twice along a 3 km inner-city route, passing four intersections with different priority rules. The cyclists were free to choose how to negotiate the intersections. Speed and the traffic surroundings were recorded via gps and cameras on the bike of the participant and of a following experimenter. For each cyclist, the ‘base’ speed on undisturbed segments was determined as reference. Based on this, the efficiency in different types of intersections was computed per cyclist group. It turned out that infrastructural aspects, cyclist group and the presence and behaviour of interacting traffic influenced cyclist efficiency. Faster cyclists were delayed more when the infrastructure required a stop regardless of the traffic situation, like at a red traffic light or a stop sign. The members of the so-called ‘comfort cyclists’ group were delayed the most in a roundabout with mixed traffic, where many chose to get off their bike and walk. In a society working for equality of access to the transport system, it is recommended to develop solutions that consider and accommodate the behaviours of different cyclist groups when planning bicycling infrastructure.     

Research on the transition marking between the broken line and solid line of expressway

Drivers often cross the solid line unintentionally during the lane-changing, when the sight distance is blocked by the vehicle ahead. There are significant potential risks to change lanes in solid line area, which would cause traffic flow disruption and traffic safety hazards. If the drivers with limited sight distance can be reminded in advance that the lane marking ahead is a solid line, many drivers will refrain from changing lanes in the restricted area, therefore, it is important to help the drivers with limited sight distance to obtain the information of lane marking ahead. There is limited research on this specific issue presently, nor any relevant regulations or manuals available in China. This paper puts forward a novel concept of transition marking, and a creative approach by adding the transition marking between the broken line and the solid line. The transition marking is considered an information carrier to predict the pass-through right of the road ahead. We have studied the form and length of the transition marking and evaluated its effectiveness through the driving simulation experiment. The form analysis shows that the white mutation broken line has better visibility and legibility. The transition marking length is shown to be closely related to the vehicle speed and distance. The simulation results indicate that the transition marking length is negatively correlated with vehicle distance and positively correlated with speed. Based on the simulation results and detailed statistical analysis, the reference value of transition marking length is proposed. The effectiveness evaluation demonstrates that the transition marking reduces the probability of solid-line crossing during lane-changing dramatically by 92%.     

The effect of speed limit credibility on drivers' speed choice

Credibility of speed limits is a key factor affecting drivers’ compliance with speed limits. Two experiments were conducted to investigate how credibility of speed limits affects judgments of appropriate speed. The first experiment aimed to establish speeds deemed appropriate by investigating Malaysians drivers’ judgments of the appropriate speed to drive based on photographs of roads with the speed limit sign erased. Drivers chose speeds which correlated with but were higher than the actual speed limits of the roads. Analysis of road characteristics suggested they based their decisions mainly on features of the road itself rather than of the roadside. The second experiment tested the impact of credibility of speed limit information on the speed drivers judged appropriate. Drivers judged the appropriate speed to drive for the same photographs as in Experiment 1 with speed limit information provided. Four conditions were included: two conditions where the speed limit posted was 10% higher or 10% lower than the appropriate speed established in Experiment 1 (credible speed limits), and two conditions where the posted speed limit was 50% higher or 50% lower than the appropriate speed (non-credible speed limits). Posted speed limits did affect drivers’ judgments about the appropriate speed to drive. Credibility also influenced judgments whereby drivers selected appropriate speeds consistent with the speed limits for the 10% lower condition, but not for speed limits that deviated highly from the appropriate speed judged in Experiment 1.