VTechWorks Repository :: Browsing by Author "Klauer, Charlie"

Browsing by Author "Klauer, Charlie"

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Advanced Driver Assistance Systems and Older Drivers – Mobility, Perception, and Safety
Liang, Dan (Virginia Tech, 2023-10-25)
The aging process is often accompanied by declines in one or more physical, vision, and/or cognitive abilities that may impact driving safety. As older drivers become more self-aware of these functional deficits, they have the tendency to engage in self-regulation practices, such as less driving and avoiding challenging driving situations. This tendency may gradually evolve to give up driving altogether. Advanced Driver Assistance Systems (ADAS) holds promise for improving older drivers' safety on the road as well as maintaining their mobility by compensating for declines in visual, cognitive, and physical capabilities. However, the perception of these technologies can influence the realization of these expected benefits. The overarching goal of this research is to understand and enhance the safety and mobility of older adults by examining the impact of ADAS. The dissertation addresses this goal by investigating mobility, perception, safety measures, and safety. Study 1 employed structure equation modeling (SEM) on the data from the Second Strategic Highway Research Program (SHRP 2) on driving habits with respect to age, gender, living status, health, and functioning capabilities. The results illustrate that older drivers' health is a reliable predictor of driving exposure, and cognitive and physical declines are predictive of their intention to reduce exposure and actual driving in challenging situations. These findings highlight that the aging population requires support for their mobility and likely road safety given their age-related impairments. Study 2 employed structure topic modeling on a focus group of older adults driving vehicles equipped with ADAS for six weeks was conducted to reveal five key issues to older drivers (in the order of prevalence): (1) safety, (2) confidence concerning ADAS, (3) ADAS functionality, (4) user interface/usability, and (5) non-ADAS related features. The findings point to a need for holistic ADAS design that not only must consider safety concerns but also user interfaces accommodating older adults' preferences and limitations as well as in-depth training programs to operate ADAS given the technology limitations. Study 3 employed correlation analysis and logistic regression on SHRP 2 data to reveal that the longitudinal deceleration events at greater than 0.60g and lateral acceleration events at greater than 0.40g appear most associated with older adults' driving risk and are predictive of near future crash and near-crashes (CNCs) occurrence and high-risk older drivers with acceptable accuracy. These findings indicate that high g-force events can be used to assess risk for older drivers, and the selection of thresholds should consider the characteristics of drivers. Study 4 compared high g-force events between two naturalistic driving studies to reveal that drivers who drove vehicles equipped with ADAS had lower longitudinal declaration rates, indicating the benefits of ADAS presence on older drivers' safety. When lane keeping assist (LKA) was engaged, lower high longitudinal deceleration was observed than when LKA was not engaged, indicating that older drivers tended to apply less aggressive braking when using LKA. Over several weeks of exposure to vehicles with ADAS presence, older drivers showed decreasing longitudinal deceleration but increasing lateral acceleration events. In other words, the potential of ADAS for positive safety-related impacts exists but some refinement in the design to reduce lateral events might be necessary.
Allusion 2: External Communication for SAE L4 Vehicles
Rossi-Alvarez, Alexandria I.; Klauer, Charlie; Schaudt, Andy; Doerzaph, Zac (Safe-D University Transportation Center, 2023-12)
With SAE Level 4 and above (L4+) Automated Driving Systems (ADSs) being integrated on roadways, stakeholders worldwide are developing external communication systems for other road users to communicate effectively. Most research on SAE L4+ ADS external communication has used simulators or virtual reality platforms to assess driver/road user knowledge, opinions, and attitudes via survey metrics evaluating a single L4 vehicle. However, it is vital to understand perception of external communication in real-world conditions and with multiple SAE L4+ ADSs present. This research explored how the presence of multiple SAE L4+ ADSs with external communication displays affected participants’ crossing decisions. A within-subject design assessed participants’ understanding of SAE L4+ ADS intentions. Results indicated that the presence and condition of external human-machine interfaces (eHMIs) did not influence willingness to cross. It was difficult for participants to focus on the eHMI when multiple vehicles competed for their attention. Participants typically focused on the vehicle that was nearest and most detrimental to their crossing path. Scenario type caused participants to make more cautious crossing decisions but did not influence willingness to cross. This study implies that eHMI with two patterns may still require simplification for pedestrians to interpret in a complicated traffic environment.
Analysis of Run-off-road Safety-critical Events in Virginia
Turturici, Marissa; Noble, Alexandria M.; Klauer, Charlie (National Surface Transportation Safety Center for Excellence, 2021-05-27)
Run-off-road (ROR) crashes account for a large proportion of fatalities on U.S. roadways. ROR crashes usually involve a single vehicle and occur when the vehicle departs the roadway and then strikes an object. The research presented here analyzed data from three sources: police-reported data from ROR crashes involving teens in Virginia, and data from two naturalistic driving studies conducted with teens in Virginia (the Supervised Practice Driving Study and the Driver Coach Study). The data from the police reports were provided by the Virginia Department of Motor Vehicles (DMV) and Virginia Department of Transportation (VDOT). The two datasets were heterogeneous in terms of the method of data collection and types of ROR events that comprised the majority of cases (e.g., crashes vs. near-crashes). However, results showed several commonalities in ROR events involving teens and the characteristics of these events. For example, most ROR events occurred on dry roads for both datasets. In addition, ROR events were most common on straight roads with level alignment for both datasets. Finally, both datasets showed the highest proportion of ROR events in daylight, followed by darkness without lighting. Speeding was a common driver behavior noted in both datasets but was more common for the naturalistic dataset. Driver secondary tasks were difficult to compare across datasets because police reports often report no secondary task engagement or that it was not applicable to the case, whereas naturalistic driving data allows direct observation of secondary task engagement. Thus, in the DMV data, when secondary task engagement was observed, the most common task was using a cell phone, whereas the naturalistic data showed that talking with a passenger was most common.
Assessing Alternate Approaches for Conveying Automated Vehicle Intentions
Basantis, Alexis Rae (Virginia Tech, 2019-10-30)
Objectives: Research suggests the general public has a lack of faith in highly automated vehicles (HAV) stems from a lack of system transparency while in motion (e.g., the user not being informed on roadway perception or anticipated responses of the car in certain situations). This problem is particularly prevalent in public transit or ridesharing applications, where HAVs are expected to debut, and when the user has minimal training on, and control over, the vehicle. To improve user trust and their perception of comfort and safety, this study aimed to develop more detailed and tailored human-machine interfaces (HMI) aimed at relying automated vehicle intended actions (i.e., "intentions") and perceptions of the driving environment to the user. Methods: This project developed HMI systems, with a focus on visual and auditory displays, and implemented them into a HAV developed at the Virginia Tech Transportation Institute (VTTI). Volunteer participants were invited to the Smart Roads at VTTI to experience these systems in real-world driving scenarios, especially ones typically found in rideshare or public transit operations. Participant responses and opinions about the HMIs and their perceived levels of comfort, safety, trust, and situational awareness were captured via paper-based surveys administered during experimentation. Results: There was a considerable link found between HMI modality and users' reported levels of comfort, safety, trust, and situational awareness during experimentation. In addition, there were several key behavioral factors that made users more or less likely to feel comfortable in the HAV. Conclusions: Moving forward, it will be necessary for HAVs to provide ample feedback to users in an effort to increase system transparency and understanding. Feedback should consistently and accurately represent the driving landscape and clearly communicate vehicle states to users.
Assessing the Effects of Driving Inattention on Relative Crash Risk
Klauer, Charlie (Virginia Tech, 2005-11-07)
While driver distraction has been extensively studied in laboratory and empirical field studies, the prevalence of driver distraction on our nation's highways and the relative crash risk is unknown. It has recently become technologically feasible to conduct unobtrusive large-scale naturalistic driving studies as the costs and size of computer equipment and sensor technology have both dramatically decreased. A large-scale naturalistic driving study was conducted using 100 instrumented vehicles (80 privately-owned and 20 leased vehicles). This data collection effort was conducted in the Washington DC metropolitan area on a variety of urban, suburban, and rural roadways over a span of 12-13 months. Five channels of video and kinematic data were collected on 69 crashes and 761 near-crashes during the course of this data collection effort. The analyses conducted here are the first to establish direct relationships between driving inattention and crash and near-crash involvement. Relative crash risk was calculated using both crash and near-crash data as well as normal, baseline driving data, for various sources of inattention. Additional analyses investigated the environmental conditions drivers choose to engage in secondary tasks or drive fatigued, assessed whether questionnaire data were indicative of an individual's propensity to engage in inattentive driving, and examined the impact of driver's eyes off the forward roadway. The results indicated that driving inattention was a contributing factor in 78% of all crashes and 65% of all near-crashes. Odds ratio calculations indicated that fatigued drivers have a 4 times higher crash risk than alert drivers. Drivers engaging in visually and/or manually complex tasks are at 7 times higher crash risk than alert drivers. There are specific environmental conditions in which engaging in secondary tasks or driving fatigued is deemed to be more dangerous, including intersections, wet roadways, undivided highways, curved roadways, and driving at dusk. Short, brief glances away from the forward roadway for the purpose of scanning the roadway environment (e.g., mirrors and blind spots) are safe and decrease crash risk, whereas such glances that total more than 2 seconds away from the forward roadway are dangerous and increase crash risk by 2 times over that of more typical driving.
Assessment of the Effectiveness of Emergency Lighting, Retroreflective Markings, and Paint Color on Policing and Law Enforcement Safety
Terry, Travis N. (Virginia Tech, 2020-07-01)
This project is an in-depth investigation on the impact of lighting, marking and paint schemes on the operational aspects of police vehicles. This investigation consisted of two phases that ultimately consisted of four experiments. An array of lighting and marking schemes were implemented on police vehicles in a variety of jurisdictions for evaluation. The study then investigated the change in the visibility of police officers, the public reaction to these schemes, and the operational impacts of these systems. The first phase of the project was a naturalistic observation study where the goal was to better understand how traffic behaved around traffic stops. Test vehicles were positioned in simulated traffic stops and patrol locations to determine how traffic behavior was affected by various configurations of police lighting and markings. Camera and radar systems were used to measure the changes in driver speed and when drivers responded to the move over law. Based on the results of the naturalistic studies, the impact of the lighting system on officer visibility was investigated in a controlled human factors test where the ability of a driver to see a police officer outside of their vehicle was measured in the presence of the lighting systems. The purpose of this interjected effort was to verify that the experimental schemes would not increase risk to law enforcement despite data from the first phase indicating the vehicles were more visible. A second part to that study evaluated conventional methods of bolstering an officer's visibility outside of their vehicle at night. The second phase took the findings of the first phase and implemented changes to several police vehicles from local and state agencies to be in operation for at least 18 months. This was to assess the rate of near-misses and crash rate to relate the vehicle changes to law enforcement safety. Additionally, rates of citations were assessed, and surveys offered an opportunity for law enforcement to provide their own feedback on the implementations. The lighting systems evaluated included a completely blue lighting system, an enhanced all blue lighting system with twice the light output, a red and blue system, and a single flashing blue beacon. In terms of markings, retroreflective markings along the side of the vehicle, a retroreflective contour line, chevrons on the rear of the vehicle and unmarked vehicles were evaluated. Finally, a variety of vehicle colors were used to investigate the impact of the base vehicle paint color. The results indicate that both the red and blue lighting system and the high output blue lighting system increase the distance at which drivers moved over significantly. In general, at least 95% of traffic attempted to merge away from an actively lighted police vehicle, when possible. In terms of the speed change, drivers began reducing their speed by approximately 600 m from the police vehicle. Similarly, the addition of retroreflectivity to the rear of the vehicle showed an additional benefit for causing drivers to move over sooner. However, these benefits came at a cost to the officer's visibility. When outside of their vehicle, the high output blue system significantly reduced officer detectability while the red and blue configuration only impacted detection distance by 3 meters. The investigation did find that these impacts could be overcome with retroreflective vests worn by the officers. In the second phase, a preference revealed by officers favored the red-blue configuration. They stated that this configuration provided greater comfort for them and less glare to approaching drivers. The study also revealed that the alternative configurations did not impact the operational activities of police authority.
Behavioral Adaptation to Driving Automation Systems: Guidance for Consumer Education
Noble, Alexandria Marie (Virginia Tech, 2020-04-15)
Researchers have postulated that the implementation of driving automation systems could reduce the prevalence of driver errors, or at least mitigate the severity of their consequences. While driving automation systems are becoming increasingly common on new vehicles, drivers seem to know very little about them. The following dissertation describes an investigation of driver behavior and behavioral adaptation while using driving automation systems in order to improve consumer education and training. This dissertation uses data collected from test track environments and two naturalistic driving studies, the Virginia Connected Corridor 50 (VCC50) Vehicle Naturalistic Driving Study and the NHTSA Level 2 Naturalistic Driving Study (L2 NDS), to investigate driver behavior with driving automation systems and make suggestions for modifications to current consumer education practices. Results from the test track study indicated that while training strategy elicited limited differences in knowledge and no difference in driver behaviors or attitudes, operator behaviors and attitudes were heavily influenced by time and experience with the driving automation. The naturalistic assessment of VCC50 data showed that drivers tended to activate systems more frequently in appropriate roadway environments. However, drivers spent more time looking away from the road while driving automation systems were active and drivers were more likely be observed browsing on their cell phones while using driving automation systems. The analysis of L2 NDS showed that drivers' time gap preferences changes as drivers gain experience using the driving automation systems. Additionally, driver eye glance behavior was significantly different with automation use and indicated the potential for an adaptive trend with increased exposure to the system for both glances away from the roadway and glances to the instrument panel. The penultimate chapter of this work presents training guidelines and recommendations for consumer education with driving automation systems based on this and other research that has been conducted on driver interaction with driving automation systems. The results of this research indicate that driver training should be a key focus in future efforts to ensure the continued safe use of driving automation systems as they continue to emerge in the vehicle fleet.
Contributing Factors to Run-off-road Crashes and Near-crashes
McLaughlin, Shane B.; Hankey, Jonathan M.; Klauer, Charlie; Dingus, Thomas A. (United States. National Highway Traffic Safety Administration, 2009-01)
The purpose of this investigation is to identify factors associated with run-off-road (ROR) crashes. Events from the 100-Car Naturalistic Driving Study that constituted ROR crash or near-crash events were investigated to identify conditions in which the events occurred and contributing factors. ROR events occur more frequently per mile in low-visibility (including darkness) and low-friction conditions than in clear and dry conditions. Approximately half of the events (56%) occurred on straight roadways, with the remainder occurring in curves (30%) and intersection turns (14%). The most frequently identified contributing factor among the ROR events was distraction. Changes in roadway boundaries (e.g., discontinuities) also appear to be a common factor. Short following distances appear to be more commonly a factor than lead-vehicle braking. Other factors include fatigue/impairment, low friction, vehicle encroaching on the subject vehicle, low-speed maneuvering errors, and late route selection.
Developing a Teen Driving Meta-Database Using Three Naturalistic Teen Driving Studies Plus Driver Coach Study
Klauer, Charlie; Hua, Lesheng; Dingus, Thomas A. (2024-01-25)
Motor vehicle collisions are the leading cause of death for teens aged 16 to 19. The risk of motor vehicle crashes is higher among teens aged 16 to 19 than among any other age group. Despite great interest in teen risky driving, little objective information about its prevalence is available. The Naturalistic Teenage Driving Study (NTDS), conducted at the Virginia Tech Transportation Institute (VTTI), provided a rich and powerful dataset, which permits researchers to evaluate driving performance over long periods and provide objective measures of driving risks and contributing factors. However, the NTDS only had 42 novice drivers from southwest Virginia. With the lack of other naturalistic studies of novice teenage driving for comparison, its findings are tentative and need further exploration and confirmation. More NDSs are needed to obtain additional crash data and determine what factors could lead to teen risky driving. Using the trigger thresholds from the NTDS, event databases were created from the Supervised Practice Driving Study (SPDS), the SPDS Attention Deficit and Hyperactivity Disorder (ADHD) Cohort NDS, the Second Strategic Highway Research Program (SHRP 2) NDS, and the Driver Coach Study. Similarly, a database of baseline epochs, per guidelines from the NTDS, was also developed for each of these studies. All event and baseline databases from all five studies were combined into one database to perform meta-analyses using naturalistic teenage driving data. This database is the most complete naturalistic teenage driving database in the world. Many of the key analyses that were performed on only 42 teenage drivers in the NTDS can now be performed on 489 novice drivers from seven locations around the U.S. In this report, we describe each database briefly, including the ADHD teen study, and provide notations about purpose, methods, measures, and instrumentation. We then review what have learned from each database about young driver crash risk. Studies based on the meta-database mainly focused on the prevalence of teen secondary task engagement, distraction, risky driving behavior, and progression of driving skill, as well as the associated crash risks for these behaviors. New projects and new work that this tool has already yielded are described herein, and additional work that still needs to be done is outlined.
Development of Curriculum for the Virginia Driver's Licensing Ceremony
Duke, Rebekah; Klauer, Charlie; Baker, Stephanie Ann (National Surface Transportation Safety Center for Excellence, 2017-12-06)
In Virginia, to receive the actual driver’s license (as opposed to the temporary driving permit), both a parent and the teenage driver must appear before a family district court judge and participate in the Virginia Driver’s Licensing Ceremony. This is an opportune moment when safety information is disseminated to parents and their novice drivers. These ceremonies are written and created primarily by district court judges. While some judges have taken a great deal of time and compiled excellent information, others are unsure about the information that should be relayed. The purpose of this project was to develop a PowerPoint presentation and handout based on contemporary teen driving research and to disseminate the materials to district court judges throughout the state of Virginia for use in their licensing ceremonies. The PowerPoint presentation included the slides but also was accompanied with a script for the judges to use during the presentation. The slides and script provide parents and teens with key safety information, including the driving risks teens face, the Graduated Driver Licensing (GDL) laws in Virginia, and how to use a parent-teen driving contract as a mechanism for risk reduction and parental management.
Do Real-time and Post Hoc Feedback Reduce Teen Drivers' Engagement in Secondary Tasks?
Hua, Lesheng; Ankem, Gayatri; Noble, Alexandria; Baynes, Peter; Klauer, Charlie; Dingus, Thomas A. (National Surface Transportation Safety Center for Excellence, 2023-08-02)
In 2020, 2,800 teens in the United States between the ages of 13 and 19 were killed in motor vehicle crashes (Centers for Disease Control and Prevention, 2023). The purpose of this study is to assess if there is an additional benefit to the driver feedback system implemented in the Driver Coach Study (Klauer et al., 2017) on secondary task reduction and if the same trends of parental involvement are observed. The data used in this study were drawn from two previously completed naturalistic driving studies involving teenage drivers. The Driver Coach Study recruited 90 teen-parent dyads and presented the teen driver with feedback on their driving performance for the first 6 months (Klauer et al., 2017). Parents were able to review a website that provided information on the feedback that their teen received. The Driver Coach Study data were compared to the Supervised Practice Driving Study, which observed 88 teenage drivers during naturalistic driving in the same geographic location who did not receive feedback. Novice driver secondary task engagement was recorded. Parental involvement was examined by tracking which teen/parent groups checked the website and which did not. Results suggest that teen drivers who received feedback were overall less likely to engage in secondary tasks as well as less likely to multitask than those teen drivers who did not receive feedback. Additionally, females generally engaged in secondary tasks more often than males. Teen drivers whose parents logged in to the feedback website also reduced their engagement in some secondary tasks but not all. Unfortunately, no significant reduction in cell phone use was observed between teen drivers who received feedback and those who did not. Overall, the results suggest that further research should be conducted, as monitoring and feedback for teen drivers does reduce overall secondary task engagement.
Driver Coach Study: Using Real-time and Post Hoc Feedback to Improve Teen Driving Habits
Klauer, Charlie; Ankem, Gayatri; Guo, Feng; Baynes, Peter; Fang, Youjia; Atkins, Whitney; Baker, Stephanie Ann; Duke, Rebekah; Hankey, Jonathan M.; Dingus, Thomas A. (National Surface Transportation Safety Center for Excellence, 2017-12-08)
Novice teenage drivers have the highest rates of fatalities and injuries on U.S. roadways compared to any other age group. This experimental research was conducted to see if presenting novice teenage drivers and their parents with feedback on teen driving performance could decrease rates of crash/near-crash (CNC) involvement. Ninety-two newly licensed teens had their vehicles instrumented with a data acquisition system (the Virginia Tech Transportation Institute’s MiniDAS) and received driving feedback in the form of a light and a tone when a potentially risky behavior was detected. Behaviors, such as swerving, speeding, lane changing without a turn signal, hard braking, hard turning, and fast starts, were used to determine when feedback was administered. Feedback continued for six months and then was turned off for one month (in the seventh month) to determine if risky behaviors returned after feedback stopped. These data were compared to a separate study (the Supervised Practice Driving Study [SPDS]) of 90 teenage drivers in the same geographic location who did not receive feedback. Parental involvement was examined by tracking which teen/parent groups checked the website and which did not. Results suggest that real-time and post hoc feedback produce a relative reduction in the rate of CNC involvement, but only when the parent is logging in to the website. If parents do not log in to the website to review the coachable events, real-time and post hoc feedback do not improve CNC rates. The analyses also indicated that once feedback was turned off in Month 7, teen CNC rates returned to baseline levels, which suggests that 6 months of feedback is not enough time to instill safe driving habits in novice drivers. This result also suggests that parental involvement in driver education must continue through the independent driving phase to improve teen CNC rates. In general, these results support previous research on monitoring and feedback, which suggest that parental involvement is critical in improving teen driving safety. These results also support current Graduated Driver’s Licensing (GDL) policies and provide research-based evidence that these policies should be strengthened.
Driver Training Research and Guidelines for Automated Vehicle Technology
Manser, Michael P.; Noble, Alexandria M.; Machiani, Sahar Ghanipoor; Shortz, Ashley; Klauer, Charlie; Higgins, Laura L.; Ahmadi, Alidad (SAFE-D: Safety Through Disruption National University Transportation Center, 2019-07)
The advent of advanced driver-assistance systems presents the opportunity to significantly improve transportation safety. Complex sensor-based systems within vehicles can take responsibility for tasks typically performed by drivers, thus reducing driver-related error as a source of crashes. While there may be a reduction in driver errors, these systems fundamentally change the driving task from manual control to supervisory control. A significant challenge, given this fundamental change in the driving task, is that there are no established methods to train drivers on the use of these systems, which may be counterproductive to safety improvements. The aim of the project was to develop training protocol guidelines that could be used by advanced driver-assistance system trainers to optimize driving safety. The guidelines were developed based on the results of three activities that included the development of a taxonomy of the knowledge and skills necessary to operate advanced driver-assistance systems, a driving simulator study that examined the effectiveness of traditional training protocols, and a test track study that examined the efficacy of a vehicle-based training protocol. Results of both studies suggest that differing training protocols are most beneficial in terms of driver cognitive load and visual scanning as opposed to short-term changes in performance.
The Effect of Novel External Communication Display on Pedestrian Judgements of Acceleration
Radlbeck, Joshua (Virginia Tech, 2024-06-07)
Pedestrian fatalities are on the rise in the United States, and this trend shows no signs of reversing. One contributing factor to these incidents is pedestrians' difficulty in accurately assessing traffic conditions and vehicle actions, leading to potentially fatal collisions. One promising solution could be the use of additional visual cues through external vehicle lighting on the front of vehicles to aid pedestrians in making safer decisions. This research explored this possibility through two studies that examined an LED display mounted on the grill of a study vehicle. The display changed color to communicate whether the vehicle was accelerating or decelerating (the display turned white if the vehicle was accelerating, and amber if the vehicle was decelerating). The first study assessed how well participants could judge whether the vehicle was accelerating or decelerating when the display was active versus inactive, and whether a verbal explanation of the display's function improved their understanding. The second study not only revisited judgement accuracy, but also examined its influence on participants' crossing intentions. Additionally, this study evaluated if repeated exposure to the display in a different traffic scenario (maneuvering a left turn at a stop sign controlled intersection) enhanced understanding as well as verbal explanations, which are less feasible in real world traffic situations. Findings from these studies indicated that a clear verbal explanation of the display significantly enhanced participants' ability to discern vehicle acceleration and deceleration, but exposure to the display in other traffic scenarios provided the same benefit. Study 2 did not observe significant changes in the safety buffer (i.e. the amount of time between when participants decide to cross, and when there would be a conflict with the vehicle if they did cross), but the average number of safe crossing decisions versus unsafe was improved, though these results were inconsistent across participants. These findings suggest potential for enhancing pedestrian safety by providing pedestrians with additional information through external vehicle lighting displays. Future research should focus on optimal implementations strategies for such displays and investigate any possible unintended consequences of deploying this technology on public roads.
Effectiveness of Compensatory Vehicle Control Techniques Exhibited by Drivers after Arthroscopic Rotator Cuff Surgery
Metrey, Mariette Brink (Virginia Tech, 2023-07-10)
Current return-to-drive recommendations for patients following rotator cuff repair (RCR) surgery are not uniform due to a lack of empirical evidence relating driving safety and time-after-surgery. To address the limitations of previous work, Badger et al. (2022) evaluated, on public roads, the driving fitness of patients prior to RCR and at multiple post-operative timepoints. The goal of the Badger, et al. study was to make evidence-based return-to-drive recommendations in an environment with higher fidelity than that of a simulator and not subject to biases inherent to surveys. Badger et al., however, do not fully investigate the driving practices exhibited by subjects, overlooking the potential presence of compensatory driver behaviors. Further investigation of these behaviors through observation of direct driving techniques and practices over time can specifically answer how drivers may modify their behaviors to address a perceived state of impairment. Additionally, the degree of success in vehicle operation by comparing an ideal turn to the path taken by the driver allows for a level of quantification of the effectiveness of the compensatory techniques. Moreover, driver trajectories inferred from the vehicle Controller Area Network (CAN) metrics and from global positioning system (GPS) coordinates are contrasted with the ideal turn to assess minimum requirements for future sensors that are used to make these trajectory comparisons. This investigation leverages pre-existing data collected by the Virginia Tech Transportation Institute (VTTI) and Carilion Clinic as used in the analysis performed by Badger et al. (2022). RCR patients (n=27) executed the same prescribed driving maneuvers and drove the same route in a preoperative state and at 2-, 4-, 6-, and 12-weeks post operation. Behavioral data were annotated to extract key characteristics of interest and related them to relevant vehicle sensor readings. To construct vehicle paths, data was obtained from the on-board data acquisition system (DAS). Behavioral metrics considered the use of ipsilateral vehicle controls, performance of non-primary vehicle tasks, and steering techniques utilized to assess the impact of mobility restrictions due to sling use. Sling use was found to be a significant factor in use of the non-ipsilateral hand associated with the operative extremity (i.e., operative hand) on vehicle functions and, in particular, difficulty with the gear shifting control. Additionally, when considering the performance of non-primary vehicle tasks as assessed through a prescribed visor manipulation, sling use was not a significant factor for the task duration or completion of the task in a fluid motion. Sling use was, however, significant with respect to operative hand position prior to the completion of the visor manipulation: the operative hand was often not on the steering wheel prior to the visor maneuver. In addition, the operative hand was never used to manipulate the visor when the sling was worn. One-handed steering was also more frequent with the presence of the sling. Further behavioral analysis assessed the presence of compensatory behavior exhibited by subjects during periods in which impairment was perceived. Perceived impairment was observed as a function of the different experimental timepoints. Findings indicated a significant decrease in the lateral vehicle jerk during post-operative weeks 6 and 12. Significant differences, however, were not observed in body position alteration to avoid contact with the interior vehicle cabin, in over-the-shoulder checks, and in forward leans during yield and merge maneuvers. Regarding trajectory analysis, sling use did not produce a significant difference in the error metrics between the actual and ideal paths. In completion of turning maneuvers, however, operative extremity was significant for left turns, with greater error against the ideal path observed from those in the left operative cohort compared to those in the right operative cohort. For the right turn, however, operative extremity was not found to be a significant factor. In addition, the GPS data accuracy proved insufficient to support comparison against the ideal path. Overall, findings from this study provide metrics beyond those used in Badger, et al. that can be used in answering when it is safe for rotator cuff repair patients to return-to-drive. With the limited differences observed as a function of study timepoint and sling use, it is recommended that patients are able to safely return-to-drive at two weeks post-operation. If anything, results suggest that overcompensation, as inferred from observation of safer driving behaviors than normal, is present during some experimental timepoints, particularly post-operative week 2.
Effectiveness of Vehicle External Communication Toward Improving Vulnerable Road User Safe Behaviors: Considerations for Legacy Vehicles to Automated Vehicles of the Future
Rossi-Alvarez, Alexandria Ida (Virginia Tech, 2023-01-25)
Automated vehicles (AVs) will be integrated into our society at some point in the future, but when is still up for debate. An extensive amount of research is being completed to understand the communication methods between AVs and other road users sharing the environment to prepare for this future. Currently, researchers are working to understand how different forms of external communication on the AVs will impact vulnerable road user (VRU) interaction. However, within the last 10 years, VRU casualty rates have continued to rise for all classifications of VRUs. Unfortunately, there is no suggestion that pedestrian fatality rates will ever decrease without some intervention. This dissertation aims at understanding the impacts of eHMI across real-world, complex scenarios with AVs and how researchers can apply those future findings to improve VRUs' judgments to today. A series of studies evaluated the necessity and impact of eHMI on AV–VRU interaction, assessed how the visual components of eHMI influenced VRU crossing decisions, and how variations in a real-world environment (multiple vehicles and scenario complexity) impact crossing decision behavior. Two studies examined how eHMI will impact future interactions between AVs and VRUs. Specifically, to understand how to advance the design of these future devices to avoid unintended consequences that may result. Results from these studies found that the presence and condition of eHMI did not influence participants' willingness to cross. Participants primarily relied on the speed and distance of the vehicle to make their crossing decision. It was difficult for participants to focus on the eHMI when multiple vehicles competed for their attention. Participants typically prioritized their focus on the vehicle that was nearest and most detrimental to their crossing path. Additionally, the type of scenario caused participants to make more cautious crossing decisions. However, it did not influence their willingness to cross. The last study applied the learnings from the first two studies to a foundational perception study for current legacy vehicles. These results showed a significant increase in judgment accuracies with a display. Through analysis across overall conclusions from the 3 studies, five critical findings were identified when addressing eHMI and 3 design recommendations, which are discussed in the penultimate section of this work. The results of this dissertation indicate that eHMI improved VRUs' accuracy of perception of change in vehicle speed. eHMI did not significantly impact VRUs crossing decisions. However, the complexity of the traffic scenarios affected the level of caution participants exhibited in their crossing behavior.
Effects of Augmented Reality Head-up Display Graphics’ Perceptual Form on Driver Spatial Knowledge Acquisition
De Oliveira Faria, Nayara (Virginia Tech, 2019-12-16)
In this study, we investigated whether modifying augmented reality head-up display (AR HUD) graphics’ perceptual form influences spatial learning of the environment. We employed a 2x2 between-subjects design in which twenty-four participants were counterbalanced by gender. We used a fixed base, medium-fidelity driving simulator at the COGENT lab at Virginia Tech. Two different navigation cues systems were compared: world-relative and screen-relative. The world-relative condition placed an artificial post sign at the corner of an approaching intersection containing a real landmark. The screen-relative condition displayed turn directions using a screen-fixed traditional arrow located directly ahead of the participant on the right or left side on the HUD. We captured empirical data regarding changes in driving behaviors, glance behaviors, spatial knowledge acquisition (measured in terms of landmark and route knowledge), reported workload, and usability of the interface. Results showed that both screen-relative and world-relative AR head-up display interfaces have similar impact on the levels of spatial knowledge acquired; suggesting that world-relative AR graphics may be used for navigation with no comparative reduction in spatial knowledge acquisition. Even though our initial assumption that the conformal AR HUD interface would draw drivers’ attention to a specific part of the display was correct, this type of interface was not helpful to increase spatial knowledge acquisition. This finding contrasts a common perspective in the AR community that conformal, world-relative graphics are inherently more effective than screen-relative graphics. We suggest that simple, screen-fixed designs may indeed be effective in certain contexts. Finally, eye-tracking analyses showed fundamental differences in the way participants visually interacted with different AR HUD interfaces; with conformal-graphics demanding more visual attention from drivers. We showed that the distribution of visual attention allocation was that the world-relative condition was typically associated with fewer glances in total, but glances of longer duration.
The Effects of Cognitive Executive Load on Driving Crashes and Near-Crashes
Sullivan, Keith Alexander (Virginia Tech, 2022-06-08)
Previous naturalistic driving studies have shown that visual and manual secondary tasks increase driving crash risk. With the increasing use of infotainment systems in vehicles, secondary tasks requiring cognitive executive demand may increase crash risk, especially for young and older drivers. Naturalistic driving data were examined to determine if secondary tasks with increasing cognitive executive demand would result in increasing crash risk. Data were extracted from the Second Strategic Highway Research Program Naturalistic Driving Study, where vehicles were instrumented to record driving behavior and crash/near-crash data. Cognitive executive and visual-manual tasks paired with a second cognitive executive task were compared to the cognitive executive and visual-manual tasks performed alone. Crash/near-crash odds ratios were computed by comparing each task condition to driving without presence of any secondary task. Dual cognitive executive tasks resulted in greater odds ratios than those for single cognitive executive tasks. The dual visual-manual tasks odds ratios did not increase from single task odds ratios. These effects were only found for young drivers. These findings help validate that cognitive executive secondary task load increases crash/near-crash risk, especially in dual task situations for young drivers. Future research should be conducted to minimize cognitive task load associated with vehicle infotainment systems using such technologies as voice commands.
The Effects of System Transparency and Reliability on Drivers' Perception and Performance Towards Intelligent Agents in Level 3 Automated Vehicles
Zang, Jing (Virginia Tech, 2023-07-05)
In the context of automated vehicles, transparency of in-vehicle intelligent agents (IVIAs) is an important contributor to drivers' perception, situation awareness (SA), and driving performance. However, the effects of agent transparency on driver performance when the agent is unreliable have not been fully examined yet. The experiments in this Thesis focused on different aspects of IVIA's transparency, such as interaction modes and information levels, and explored their impact on drivers considering different system reliability. In Experiment 1, a 2 x 2 mixed factorial design was used in this study, with transparency (Push: proactive vs. Pull: on-demand) as a within-subjects variable and reliability (high vs. low) as a between-subjects variable. In a driving simulator, twenty-seven young drivers drove with two types of in-vehicle agents during Level 3 automated driving. Results suggested that participants generally preferred the Push-type agent, as it conveyed a sense of intelligence and competence. The high-reliability agent was associated with higher situation awareness and less workload, compared to the low-reliability agent. Although Experiment 1 explored the effects of transparency by changing the interaction mode and the accuracy of the information, a theoretical framework was not well outlined regarding how much information should be conveyed and how unreliable information influenced drivers. Thus, Experiment 2 further studied the transparency regrading information level, and the impact of reliability on its effect. A 3 x 2 mixed factorial design was used in this study, with transparency (T1, T2, T3) as a between-subject variable and reliability (high vs. low) as a within-subjects variable. Fifty-three participants were recruited. Results suggested that transparency influenced drivers' takeover time, lane keeping, and jerk. The high-reliability agent was associated with the higher perception of system accuracy and response speed, and longer takeover time than the low-reliability agent. Participants in T2 transparency showed higher cognitive trust, lower workload, and higher situation awareness only when system reliability was high. The results of this study may have significant effects on the ongoing creation and advancement of intelligent agent design in automated vehicles.
Evaluation of Eyes Off Road During L2 Activation on Uncontrolled Access Roadways
Anderson, Gabrial T.; Glaser, Yi; Klauer, Charlie (2024-01)
The current study investigated eyes-off-road (EOR) behavior of drivers when traveling on uncontrolled access roadways in vehicles equipped with SAE Level 2 (L2) automated features. Previously collected naturalistic driving data were analyzed. Events were split between L2 features being active or available but inactive and matched across a spectrum of criteria (e.g., time of day). Primary analyses focused on L2 activation status and intersection type (no intersection, straight through intersection, and turning) and any interaction between those variables. EOR glances were operationalized in two ways: EOR 1, only forward was considered on road; and EOR 2, all driving-related glances were considered on road. EOR metrics involved total EOR, mean EOR, single longest glance, and number of glances per event. Overall, results for the primary research questions indicated that EOR behavior was higher when L2 was active across all EOR metrics, that intersection type affected EOR behavior on some metrics, and that there was an interaction between these variables for select metrics. Ancillary analyses represented differences for single longest glance when excluding slower speed segments, higher EOR behavior when speeds were below 37 mph, and increased hands-off-wheel behavior when L2 systems were active.

Browsing by Author "Klauer, Charlie"

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