Driver Comprehension Research Articles

Evaluation of Driver Comprehension and Compliance of Red-Colored Pavement Markings for Transit Lanes in Portland, Oregon

Many U.S. agencies have experimented with red-colored pavement markings in transit lanes to enhance the message that they are restricted to transit vehicles. This study evaluated nontransit drivers’ comprehension of and compliance with red-colored lane markings in transit priority lanes intended to communicate lane restrictions and appropriate turning and merging locations. Two complementary research methods were used: 1) an online survey of drivers’ comprehension of red-colored pavement markings, and 2) evaluation of video collected at locations pre and post installation of red-colored pavement markings. In the survey, most drivers recognized the red pavement color as a restriction on use, but most did not associate it specifically with transit, or understand the intended meaning of the broken red bar patterns designed to designate a merge area. However, we observed relatively high compliance rates with the transit lane restrictions, and the red pavement coloring was generally associated with improved compliance. Of the 22,803 vehicles observed at these locations, 206 were observed driving in the transit lanes, accounting for a violation rate of 0.9%. For the locations with pre and post data, driving-in-transit-lane violations were either reduced or there was no significant change. For locations with shared turn and transit lanes, between 62% and 76% of drivers merged as intended, and we observed an increase in appropriate merging behavior with the addition of red pavement color.

Evaluating driver comprehension of the roadway environment to retain accountability of safety during driving automation

Driver comprehension is a substantial component of situation awareness that involves the ability of an individual to understand the significance of an object, traffic sign, or hazard while driving. An increase in crashes related to autonomous driving systems has raised a concern regarding the safety of other roadway users due to the diminishing accountability resulting from a general lack of understanding of the limitations or disregard of the safety protocols by users. To keep drivers vigilant when engaged in partial automated systems, a methodology to monitor real-time driver comprehension was proposed. A driving simulator study consisting of 90 participants, equally split between males and females, was executed to establish driver comprehension in six different variations of driving difficulty. Joint probability density functions were created by considering percent time spent gazing, answers to probe questions, and driving performance. Based on these density functions, five levels of comprehension were devised and assigned thresholds. Overall, as task difficulty increased, a non-linear deterioration in driving speed along with an increase in total gaze duration was observed before comprehension was attained. A two-step validation protocol was also proposed to ensure similar levels of comprehension to non-automated driving from the human driver, when engaged in early forms of automation. The proposed real-time driver comprehension monitoring constitutes a first step toward developing a methodology to reinstate the accountability of safety of other roadway users when engaged in driver-in-the-loop automation systems.

Online Survey of Driver Comprehension of the Flashing Yellow Arrow for Right-Turn Signal Indications

This paper presents the results of an online survey of licensed driver comprehension of the right-turn signal displays with a focus on the flashing yellow arrow (FYA) and also including the circular green and red and red arrow. Recruitment postcards were mailed to a random sample of 9,872 residents in Oregon. The online survey yielded 399 responses. The open-ended responses were coded for comprehension and analyzed. The results suggest that FYA for right turns is well understood by Oregon drivers despite its current novelty (only two locations at the time of the research). Importantly, survey respondents were more likely to recognize the yielding requirement of the permissive movement and associate the yielding with pedestrians with the FYA over the circular green (CG) display. The research also confirmed that the expected driver response to the red arrow display for right turns is not well understood (only 52% of the respondents correctly stated the expected driver response). Binary logistic regression modeling revealed that the driver’s age and their educational level were significant factors in comprehension.

Evaluation of Driver Comprehension and Visual Attention of the Flashing Yellow Arrow Display for Permissive Right Turns

This research explored driver comprehension and behaviors in Oregon with respect to right-turn signal displays focusing on the Flashing Yellow Arrow (FYA) in a driving simulator. A counterbalanced, factorial design was chosen to explore three independent variables: signal indication type and active display, length of the right-turn bay, and presence of pedestrians. Driver decision-making and visual attention were considered. Data were obtained from 46 participants (21 women, 25 men) turning right 736 times in 16 experimental scenarios. A Mixed-effects Ordered Probit Model and a Linear mixed model were used to examine the influence of driver demographics on observed performance. Results suggest that the FYA indication improves driver comprehension and behavioral responses to the permissive right-turn condition. When presented with the FYA indication in the presence of pedestrians, nearly all drivers exhibited caution while turning and yielding to pedestrians and stopping when necessary. For the same turning maneuver, drivers presented with a circular green (CG) indication were less likely to exhibit correct behavior. At least for Oregon drivers, another clear finding was a general lack of understanding of the steady red arrow (SRA) display for right turns. Most drivers assume the SRA indication requires a different response than the circular red (CR) and remain stopped during the entire red interval, thus resulting in efficiency losses. These findings suggest that transportation agencies could potentially improve driver yielding behavior and pedestrian safety at signalized intersections with high volumes of permissive right turns from exclusive right-turn lanes by using the FYA display in lieu of a steady CG display.

A comprehension-based ergonomic redesign of Philippine road warning signs

Safety in the road environment is dictated by the effectiveness of road warning signs in terms of comprehensibility. Due to prevalent road accidents associated with human error and confusions with road warning signs, there is a need for signs that are not well-comprehended by drivers to be investigated and further revised. This paper aims to measure the comprehension level of road warning signs in the Philippines and propose redesigned alternative road warning signs with reference to the ergonomic principles of display design. In selecting the most suitable alternative design, an analytic hierarchy process (AHP) method is employed. It is found that more than half of the assessed signs fall below the standards set by the American National Standard Institute (ANSI), thus, leading to the proposal of alternative sign designs. To validate the significant improvement between the prior and new designs, a Mann-Whitney rank sum test is performed. The redesigned alternatives exhibited substantial improvement on the comprehension level of drivers. This implies that the application of ergonomic principles significantly increases driver comprehension level.

Evaluation of New Lane Reduction Markings

Roadway lane reduction transitions have long been reported to be problematic to drivers. It is not known whether this is the result of a lack of understanding of lane reduction markings, a simple failure to comply with such markings, or other unknown factors. This study explored driver comprehension of six different lane reduction markings. The markings varied in terms of the incorporation and length of dotted and broken lines. In addition, half of the markings included a solid white line adjacent to the dotted/broken line. The supplemental solid white line resulted in improved understanding that the rightmost lane would end, earlier reported lane changes, and the highest preference ratings. Dotted lines also resulted in better understanding of an upcoming necessary lane change than did the longer, more traditional broken lane lines. Recommendations and suggestions for lane reduction marking changes to the Manual of Uniform Traffic Control Devices are made.

ELECTRONIC TRAFFIC SIGNS: THE INTERPLAY BETWEEN HYBRID AND FULL MATRIX E-SIGNS

Road signs constitute a complex and growing communication system where different elements (pictograms, shapes, texts, etc.) are combined following different strategies. In this paper we have confronted drivers with a number of messages (congestion or road works, before, between, after location/s) developed as an adaptation of Advance Location Signs (class G, 1c in the 1968 Convention) to electronic displays. We manipulate two main factors a) the reading strategy (top-down vs. bottom-up) and the type of matrix display (hybrid, dissociating pictogram and text, vs. full matrix), in a repeated measures experimental design. The time taken to answer and the response given (correct, incorrect) was measured for each of the 24 message-blocks. Results show that the organization of the elements displayed is a key determinant for driver comprehension. Further thoughts on the need to understand the interplay between the formats adopted by static vs electronic message signs are provided. DOI: http://dx.doi.org/10.4995/CIT2016.2016.3327

Driver's Comprehension and Improvement of Warning Signs

Warning signs are effective only when users clearly understand their meaning. Three experiments were conducted in this study. In the first, the perception accuracy of warning signs was tested. This study investigated the role of age, gender, education background, and years of license in drivers' comprehension of warning signs. The populations sampled were from Nanjing city in China. A total of 12 symbolic warning signs were investigated. A questionnaire prepared to collect the data was distributed to 550 drivers. The results showed that age, gender, and driving years have no significant influence on the sign comprehension. However, the divers with higher education background present better comprehension to warning signs than those with lower education background. In the second experiment, these signs of comprehension score less than 67% in the first experiment were screened and analyzed the cause of wrong responses using semantic analysis frequency distribution method. Using the semantic analysis method, the perception errors are researched by the four features, namely, meaningfulness, recognition, simplicity, and symbol design. In the third, improvement design of warning signs was provided. Lastly, through scheme comparison and the perception of warning signs, reasonable and improved warning signs are determined to better play management and service functions. Language: en

A Study on Variable Message Signs Graphical Comparation

Variable message signs can display not only text information, but also graphic information. Graphic information can be identified further in the distance than text information. Besides, the graphical information is not limited by language, as different countries can use the same graphical signs. The paper studies driver's comprehension of various graphic of five signs via questionnaires. The results showed that driver's selection of graphical signs had significant differences; only graphic A and graphic B, and graphic B and graphic C of fog sign did not have significant differences. Based on hypothesis testing and multiple comparisons analyzed to obtain the graphics of the five signs, the conclusions provide a base reference for graphic design of highway variable message signs.

The effect of context and ergonomic design of traffic signs on driver comprehension – a preliminary evaluation

A previous study found high and statistically significant correlations between the probability of compre-hending a traffic sign and the extent to which the sign complies with three ergonomic principles of design: sign-content compatibility, familiarity, and standardization. The current study examined whether providing participants with the context in which the sign is presented might help them understand the meaning of the sign. In addition, the study presented a preliminary attempt to overcome misunderstood and poorly unders-tood signs, according to two ergonomic guidelines (compatibility and standardization). Participants were presented with 20 local road signs, both with and without providing the context in which the signs were presented, and were asked to describe their meaning. In a second experiment, the most poorly understood signs were redesigned and driver comprehension was tested again, using a new set of participants. Results showed that context had a significant positive effect on sign comprehension, and partly showed an increase in driver understanding of signs as a result of ergonomic-based redesign.

Effects of Multiple-Device Integration Strategies on Driver Comprehension of Crash Warnings

This experiment investigated the extent to which driver comprehension of imminent crash warnings is affected by the degree of integration when there are multiple Connected Vehicle products in the vehicle. Two displays were placed in an experimental vehicle: one representing original equipment and one representing a portable, nomadic device. Participants were randomly assigned to one of five device integration conditions. Participants drove on a test track and were occasionally presented with either a nonurgent message or an urgent crash warning. Participants recognized warnings most quickly when only one display was active in the car; when both displays were active, response times generally improved when messages and warnings were integrated into a single physical location. Warning recognition times were longer when a warning closely followed a non-urgent message on the other display than when a warning followed a non-urgent message on the same display. When messages and warnings from both source displays were integrated into a single display, this effect was not observed, suggesting that the separate display locations are responsible for the increased warning recognition time rather than the different formats of the messages from each source device.

Electric Vehicle Charging Station Signs: An Evaluation of Driver Comprehension and Perceived Risk

As drivers continue to purchase electric vehicles, there is an increasing demand for electric vehicle charging stations and, consequently, signing for these stations. Previous research evaluated a sign which was recommended to the Manual on Uniform Traffic Control Devices (MUTCD) team for addition to the MUTCD; however there remained concerns that drivers’ perceptions of electric vehicle charging stations signs had not been adequately addressed. The present research focused on driver comprehension and perceived risk of electric shock in regard to two electric vehicle charging station signs. Members of the driving public completed a computer-based survey which consisted of open-ended questions, rating tasks, and ranking tasks. Drivers did not necessarily associate a risk of electric shock with electric vehicle charging stations. In fact, nearly 100 percent reported that they would feel comfortable using a public electric vehicle charging station. When asked specifically about the risk of electric shock, statistically significant differences in sign alternatives arose only in the risk of electric shock implied by the sign. Further, drivers perceived the risk of shock from using an electric vehicle charging station as lower than many commonly used items which contain an electric charge (e.g., toaster, hair dryer, and extension cord). Given that both alternatives were well comprehended, either sign is suitable for use.

Comprehension of Posted Highway Traffic Signs in Iraq

Level of posted highway traffic signs (HTSs) comprehension by drivers is used to investigate the effectiveness of the posted HTSs in Iraq. Twenty four HTSs, different characteristics of drivers, and survey with questions of short answer and multiple-choice is selected for this aim. The study results show that there is an increase in the driver comprehension process of HTSs with the increasing of his level of education, level of urbanization of his residence and driving daily practice. Inverse relation occurred with the increasing of driver number of accidents. The results of this research show that it is very important to modify some of the HTSs so as to be easy for comprehending by making it more legible and more appropriateness, also it is recommended to educate drivers to raise there ability to understand the meanings of all the HTSs.

Evaluation of Comprehension and Legibility of International and Domestic Nonstandard Symbol Signs

This paper documents a research project that evaluated proposed new traffic signs to ensure that the signs were effective when human factors requirements were taken into consideration. The following sign messages were selected for symbol development and evaluation: combination horizontal alignment–advisory speed, congestion ahead, cross-street preferential lane warning, do not enter, do not pass, electric-vehicle charging station, fallen rocks, flagger ahead, low-shoulder warning, maximum width, no left turn ahead, railroad crossing on leg of roundabout, road narrows, survey crew, trolley crossing, uneven lanes, and winery. The team conducted 96 surveys to determine driver comprehension and legibility for each alternative sign design. The surveys were administered to the general driving public at the Turner–Fairbank Highway Research Center in McLean, Virginia. On the basis of driver input and the results of the comprehension and legibility testing, the research team provided recommendations on symbols that should be included in the next edition of the Manual on Uniform Traffic Control Devices.

Driver comprehension of multiple haptic seat alerts intended for use in an integrated collision avoidance system

► A haptic driver seat that intuitively displays seven unique alerts was developed. ► Driver performance was examined as the number of possible alerts was increased. ► Displaying three alerts or less did not degrade driver performance. ► Distracted drivers that received alerts had faster responses to a surprise barricade. ► Alerts evoked through unique/distanced areas that map to desired responses are best. Previous research demonstrated that a haptic driver seat can effectively convey information to drivers, and suggests that it may be an ideal method for presenting haptic information because it maintains contact with the driver. The current study progresses this research by investigating whether a haptic seat can be used as the sole method for communicating multiple and meaningfully different alerts such that drivers quickly execute the correct response maneuver. An intuitive manner for presenting up to seven haptic alerts through the driver seat was developed based on driver performance with an earlier haptic seat design. Twenty-four drivers then participated in an on-road study that, through three experiments, investigated: (1) whether driver response performance to the alerts degrades as the number of possible alerts (one, three, or seven alerts) is increased, (2) whether driver response performance to the alerts degrades when alerts are presented through the same seat location, and (3) whether the haptic seat can effectively alert distracted drivers to a surprise barricade. In Experiment 1, despite drivers always making the correct response maneuver, their manual response time and verbal response accuracy significantly degraded as the number of alerts increased from three to seven. In Experiment 2, drivers’ manual response time significantly improved when alerts were presented through unique seat locations. In Experiment 3, distracted drivers that received an alert returned their gaze to the forward roadway sooner, lifted their foot up from the throttle sooner, and pressed the brake pedal sooner than distracted drivers that did not receive an alert. Overall, the study shows that confusion and delayed responses may occur when the number of possible alerts is increased, but that the information transmitted by the haptic seat alerts can be secured if the alerts are presented through unique seat locations that are spaced far apart, and map to the desired manual response. In balancing the tradeoff between communicating a multitude of information to drivers and minimizing performance decrements, a haptic seat that conveys three alerts is recommended when quick and accurate manual responses are required and additional alert modalities are not utilized. These findings are expected to inform the design of haptic driver seats.

Driver Comprehension and Assessment of Traffic Control Devices at Signalized Intersections Interfacing with Light Rail Transit

Signalized intersections that interface with light rail transit (LRT) pose a unique challenge to traffic operations and safety. Although progress toward mitigating light rail vehicle–motor vehicle crashes has been made, many agencies still face safety issues at these intersections. Few empirical studies of the effectiveness of the safety measures currently being used have been conducted. Safety measures have not been tested with drivers; rather, the measures they have evolved over time through practice. The objectives of this research were to assess driver comprehension and to explore drivers’ perceptions and opinions of a variety of traffic control devices (TCDs) that were or that might be used at signalized intersections that interface with LRT. The research approach was to present simulated scenes to drivers with a variety of intersection scenarios and TCDs in a focus group setting. The results showed that drivers had preferences for TCDs at these intersections. Although existing TCDs are understood and generally liked, ongoing issues with safety suggest that improvements can still be made. The use of green arrow signal displays or supplemental pavement markings could improve driver situational awareness at some intersections. Enhancements to the existing Manual on Uniform Traffic Control Devices W10-7 (i.e., train icon) activated blank-out sign, such as adding the word “train” or alternating the train icon with the no left turn icon, could result in increased driver compliance. Finally, providing an active warning device on the cross street, such as the W10-7 sign, could increase safety by making drivers and pedestrians more aware of the arrival of a train.

Driver Comprehension of Messages on Truck-Mounted Changeable Message Signs during Mobile Maintenance Operations

Use of truck-mounted changeable message signs (TMCMSs) during mobile maintenance operations is desirable to provide drivers with information to better prepare them for unexpected conditions. Traditionally, temporary traffic control devices used during mobile operations have been limited to arrow boards and sometimes static warning messages mounted on a work vehicle. The use of warning signs in advance of an operation typically is not practical because of the constant movement and stop-and-go nature of the work. TMCMSs can fill an information gap for these mobile operations and provide drivers with better information about them, including actions to be expected. This paper describes the use of findings from a human factors laboratory study and basic message design principles to create a sampling of recommended messages for use on TMCMSs during mobile maintenance operations. These messages were defined by the type of work, road type, and the identified concerns to be addressed.

Guidelines for the Use of Pavement Marking Symbols at Freeway Interchanges

Pavement marking technology has advanced sufficiently to allow large multicolor symbols to be marked on the pavement. These symbols provide drivers with another source of information to help them make good navigation decisions. The objective of this research was to identify appropriate in-lane pavement marking characteristics for use near freeway interchanges. Two laptop-based surveys were conducted to evaluate driver comprehension, recognition time, and preference for different designs and applications. From the information obtained in these surveys, researchers developed the following recommendations for in-lane pavement markings near an interchange: (a) arrow and shield markings should be used in combination; (b) in simple single-lane exits (particularly traditional lane drop right exits), pavement marking symbols only need to be placed in the exit lane; (c) if in-lane pavement markings are used at complex interchanges (e.g., optional lanes, multilane exits), the markings should be applied to all lanes; (d) optional lane pavement markings should provide the same basic information as other lanes at that interchange (i.e., show both highway shields and an option arrow); (e) lane markings should not be staggered; (f) when all symbols are the same, they should be installed in a single line; and (g) the use of cardinal directions should be limited.

A Mental Model Perspective of a Driver Workload System

Conceptualizing driver mental models is not a common tool used to evaluate vehicle human-machine interfaces (HMIs) in the transportation-related literature. The presented research examines the results of a mental model exercise used to explore drivers' perception of a task mitigation workload manager. The driver workload system was designed to disable HMI functions when driving demand was estimated (by the system algorithm) to be high based on real-time assessment of the external driving environment. This paper focuses on abstracting driver comprehension of the workload system using mental model concepts.

Driver comprehension and acceptance of the active accelerator pedal after long-term use

Driver comprehension and acceptance of the active accelerator pedal (AAP) after long-term use were evaluated in a large-scale Swedish trial held in 2000-2002. The system was installed in the cars of 281 test drivers who then used it for between six months and a year. The participants' responses, elicited by questionnaires in the end of the trial, showed a positive rating of the concept of the AAP, while the willingness to pay for it was lower than for other driver-assistance systems studied elsewhere. The typically skeptical driver was a young, male, company car driver with initially negative attitude and a faulty AAP. The typically enthusiastic driver was an older, female, private driver with initially positive attitude and a fault-free AAP. The drivers found that the system, if not satisfactory, was useful but added to the emotional pressure felt by the driver. However, they did think it had positive impacts on performance and safety. Still, the largest perceived effect was a decrease in the risk of being fined for speeding. The gap between the concept of the AAP and willingness to keep and pay for the system puts a clear focus on the importance to define acceptance and developing a tool to ensure reliable assessments of it.