Stacy Balk - Academia.edu (original) (raw)

Papers by Stacy Balk

: This report documents a multi-year project effort to develop a specification for a light-emitti... more : This report documents a multi-year project effort to develop a specification for a light-emitting diode (LED) signal characteristic as an alternative to pyrotechnic, maritime distress signal flares as visual distress signals. The report includes the methodology used in evaluating color, flash pattern, and intensity for an LED distress signal, conspicuous against certain lighting conditions, at six nautical miles, in 10 miles meteorological visibility. The effort included a literature review, measurement and quantifying different levels of background lighting to recreate their effect in a vision laboratory, a series of laboratory tests to determine signal conspicuity in a controlled environment, and a field test in the marine environment. The human-subject laboratory experiments determined relative LED signal conspicuity, based on subjects' accurate identification of a signal and the response time to make that identification. The lab results (conspicuous signal characteristics)...

Between 2005 and 2009, single-vehicle run-off-road (ROR) crashes on two-lane rural-roadway horizo... more Between 2005 and 2009, single-vehicle run-off-road (ROR) crashes on two-lane rural-roadway horizontal curves have resulted in an average of 4,748 fatalities per year. Driving while familiar with the roadway, inattentive, and in a hurry have been identified as factors that increase the likelihood of these crashes. The goal of the present study was to evaluate methods that elicit familiarity with the roadway, inattention, and driving in a hurry. Fourteen participants drove a simulated two-lane rural roadway. Familiarity was elicited by having participants drive the test route seven times. Two methods to elicit inattention were used: mental mathematics problems and noun classification. Two methods to elicit being in a hurry were used: with visual travel time feedback and without. The method to elicit familiarity with the roadway resulted in significant changes in behavior when compared to driving while unfamiliar. Results suggested that solving mental mathematics problems was more effe...

A central issue in making simulators useful for highway and traffic engineers concerns how well d... more A central issue in making simulators useful for highway and traffic engineers concerns how well driver behavior in the simulator corresponds to driver behavior in the real world. Simulator fidelity plays a central role in matching behavior in the simulator to behavior on the road. Simulator fidelity often refers to the features and appearance of the simulator. The degree to which behavior in the simulator matches behavior on the road defines behavioral fidelity. This project characterized the physical fidelity and behavioral fidelity of four simulators. These four simulators represent a broad range of fidelity and cost. Data collected from these four simulators begin to address the question of how simulators can support highway and traffic engineers. Overall, the results show that simulators with high physical fidelity demonstrate high behavioral fidelity and are likely to provide good estimates of mean speeds in typical engineering applications such as roundabouts and roadway treat...

Radiation research, 2016

There is little known about the effect of both reduced weight bearing and exposure to radiation d... more There is little known about the effect of both reduced weight bearing and exposure to radiation during spaceflight on the mechanically-sensitive cartilage lining the knee joint. In this study, we characterized cartilage damage in rat knees after periods of reduced weight bearing with/without exposure to solar-flare-relevant radiation, then cartilage recovery after return to weight bearing. Male Sprague Dawley rats (n = 120) were either hindlimb unloaded (HLU) via tail suspension or remained weight bearing in cages (GROUND). On day 5, half of the HLU and GROUND rats were 1 Gy total-body X-ray irradiated during HLU, and half were sham irradiated (SHAM), yielding 4 groups: GROUND-SHAM; GROUND-IR; HLU-SHAM; and HLU-IR. Hindlimbs were collected from half of each group of rats on day 13. The remaining rats were then removed from HLU or remained weight bearing, and hindlimbs from these rats were collected on day 62. On day 13, glycosaminoglycan (GAG) content in cartilage lining the tibial ...

Distracted driving is a relevant social issue with potentially devastating consequences. In part ... more Distracted driving is a relevant social issue with potentially devastating consequences. In part due to recent calls from President Obama and United States Transportation Secretary LaHood to curb distracted driving, research on the topic is becoming more prevalent. The use of eye tracking devices in on-road vehicles is an invaluable resource to investigate driver situational awareness and attention capture. Such tools provide insight into where drivers are looking, both within and outside the vehicle, while traveling down a roadway. Data from eye trackers in a real world environment, however, present a unique set of analysis challenges. For example, there are multiple ways to quantify visual behavior (e.g., duration of fixations, percentage of time, etc.) and such quantifications are constrained to nonnegative values since a driver cannot look at an object for a negative amount of time. Additionally, responses are correlated since it is general practice to use eye movement data from...

Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2016

This study explored human factors issues associated with cooperative adaptive cruise control (CAC... more This study explored human factors issues associated with cooperative adaptive cruise control (CACC); specifically entering and exiting vehicle platoons. Participants were asked to complete one of three different types of merges in a driving simulator: (1) manual left entrance merge, (2) merge into the middle of a CACC platoon vehicles without speed assistance, and (3) merge into the middle of a CACC platoon vehicles with speed assistance. Drivers’ perceived workload was significantly less for both groups that drove with the CACC system engaged than for the group that manually maintained speed. Perhaps surprisingly, participant condition did not significantly affect physiological arousal as assessed by galvanic skin response (GSR). However, across all groups, GSR was significantly greater during the merges than during cruising/straight highway driving time periods. The two groups that had to manually adjust speed during the merge experienced collisions in 24 (18 percent) of the merge...

Most fatal collisions between vehicles and pedestrians occur at night; inadequate visibility is a... more Most fatal collisions between vehicles and pedestrians occur at night; inadequate visibility is a key factor. Previous research has shown that positioning reflective markers on pedestrians in a manner that depicts biological motion greatly enhances conspicuity. This on-road experiment examined the conspicuity advantages of a full biological motion configuration relative to that provided by an ANSI class II safety vest. 120 healthy young participants were driven along a 3.5 mile route and pressed a button when they were confident they saw a pedestrian. A test pedestrian on the left shoulder of the roadway wore black clothing with either an ANSI class II safety vest, the same vest with added ankle straps, or a full biological motion configuration. The pedestrian either faced the oncoming vehicle or the roadway while either walking in place or standing still. Response distances were maximal when motion information was present and when the pedestrian faced the test vehicle. These results

Human factors, 2020

OBJECTIVE This field study examined the effects of adaptive cruise control (ACC) on mind wanderin... more OBJECTIVE This field study examined the effects of adaptive cruise control (ACC) on mind wandering prevalence. BACKGROUND ACC relieves the driver of the need to regulate vehicle speed and following distance, which may result in safety benefits. However, if ACC reduces the amount of attentional resources drivers must devote to driving, then drivers who use ACC may experience increased periods of mind wandering, which could reduce safety. METHODS Participants drove a prescribed route on a public road twice, once using ACC and once driving manually. Mind wandering rates were assessed throughout the drive using auditory probes, which occurred at random intervals and required the participant to indicate whether or not they were mind wandering. Measures of physiological arousal and driving performance were also recorded. RESULTS No evidence of increased mind wandering was found when drivers used ACC. In fact, female drivers reported reduced rates of mind wandering when driving with ACC re...

The conspicuity of a traffic control device (TCD) is defined as the probability that the device w... more The conspicuity of a traffic control device (TCD) is defined as the probability that the device will be noticed. However, there is no agreed-upon measure of what constitutes being noticed. Various measures have been suggested, including eye fixations, recall, and verbal reports. Four conspicuity studies are discussed in this report. It has been observed that conspicuity is not solely a property of a TCD but must include consideration of the surrounding environment. The first of the studies described in this report used multidimensional scaling (MDS) to identify factors that characterize drivers’ perceptions of TCD environments. The MDS study revealed that two dimensions, clutter and predictability, characterized the roadway environments included in the study. In the second study, drivers’ eye glances to TCDs were recorded on a 34-mi (55-km) drive. After passing selected TCDs, drivers’ recall of the TCD was assessed by asking them to identify it. That study showed that warning signs ...

Ite Journal-institute of Transportation Engineers, 2018

This report presents human factors research to examine the effects of cooperative adaptive cruise... more This report presents human factors research to examine the effects of cooperative adaptive cruise control (CACC) on driver performance in a variety of situations. It summarizes driving simulator experiments in which the driver was required to drive in a stream of vehicles. Participants experienced a vehicle merge in front of them as well as an emergency event that required driver intervention. The participants' preferred following time gap did not significantly affect collision avoidance. However, those participants following at shorter distances were more likely to intervene more rapidly that those following at a far distance. These findings support the idea that performance depends more on overall CACC following distance settings than with drivers' personal preferences. This will allow CACC systems to implement a single following distance gap (or set of gaps based on vehicle physics). The results show that it is critical that drivers receive clear alerts when it is necessary to take over control of the vehicle. Without such measures, it is possible that CACC implementation may not result in improved roadway safety. This report should be useful to transportation professionals, State transportation departments, and researchers interested in the effects of automation on driver behavior and performance.

This report presents human factors experimental results from an examination of the effects of coo... more This report presents human factors experimental results from an examination of the effects of cooperative adaptive cruise control (CACC) on driver performance in a variety of situations. The experiment was conducted in a driving simulator using a scenario in which the driver was required to enter into a stream of vehicles. CACC is envisioned as an automated vehicle application that complements the capabilities of the vehicle operator without degrading the vehicle operator's alertness and attention. This task was completed with and without speed assistance during the merge. Merging maneuvers with the CACC system successfully reduced workload and eliminated collisions during merges. Drivers who were required to manually control speed and enter a continuous flow of traffic experienced a significant number of crashes, which indicated that drivers' merging maneuvers are highly sensitive to the behavior of other drivers and to merging distances. This report informs the discussion among transportation professionals about how automated vehicle applications will be embraced by everyday drivers. The experiment results should be useful to researchers and transportation professionals interested in the effects of automation on driver behavior.

This chapter provides an overview and recap of the AVS 2019 Breakout Session AVs & Vulnerable Roa... more This chapter provides an overview and recap of the AVS 2019 Breakout Session AVs & Vulnerable Road Users: Representing the Under-Represented, including summaries of research and perspective presentations from leading experts in the field and needs identified through discussion among panelists and the session audience. The session identified a range of necessary actions and research needs including defining technological, improving education about automation and advanced technology, and using these to build public trust.

Proceedings of the 9th International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle Design: driving assessment 2017, 2017

This study explored human factors issues associated with cooperative adaptive cruise control (CAC... more This study explored human factors issues associated with cooperative adaptive cruise control (CACC); specifically the relationship between drivers' preferred following distance, assigned following distance, and driving performance. Participants drove in a dedicated lane and experienced a vehicle merging in front of their vehicle and later, an emergency event that required intervention in order to avoid a collision. Drivers followed at either a near or a far distance. Drivers' perceived workload did not vary between the cruise and postmerge periods. However, workload was significantly greater after the emergency crash event. Workload did not vary significantly based on following distance assignment or preference. Those participants assigned to the near following distance were more likely to hover their foot over the brake during the merging event and to react faster to the emergency event. As with workload, performance (collision avoidance) did not vary significantly due to following distance assignment or preference. In other words, one's abilities may not necessarily reflect their following preferences. This is a promising finding for widespread implementation of CACC.

Radiation research, 2016

Proceedings of the Human Factors and Ergonomics Society Annual Meeting, 2016

Human factors, 2020

Ite Journal-institute of Transportation Engineers, 2018

Proceedings of the 9th International Driving Symposium on Human Factors in Driver Assessment, Training, and Vehicle Design: driving assessment 2017, 2017

This study explored human factors issues associated with cooperative adaptive cruise control (CAC... more This study explored human factors issues associated with cooperative adaptive cruise control (CACC); specifically the relationship between drivers' preferred following distance, assigned following distance, and driving performance. Participants drove in a dedicated lane and experienced a vehicle merging in front of their vehicle and later, an emergency event that required intervention in order to avoid a collision. Drivers followed at either a near or a far distance. Drivers' perceived workload did not vary between the cruise and postmerge periods. However, workload was significantly greater after the emergency crash event. Workload did not vary significantly based on following distance assignment or preference. Those participants assigned to the near following distance were more likely to hover their foot over the brake during the merging event and to react faster to the emergency event. As with workload, performance (collision avoidance) did not vary significantly due to following distance assignment or preference. In other words, one's abilities may not necessarily reflect their following preferences. This is a promising finding for widespread implementation of CACC.