Browsing by Author "Gibbons, Ronald B."

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    4U Lighting – Cooperative Headlighting
    Palmer, Matthew; Tsuda, Hiroshi; Williams, Brian M.; Gibbons, Ronald B. (National Surface Transportation Safety Center for Excellence, 2019-10-31)
    The purpose of this project was to evaluate the effectiveness of an alternative cooperative headlighting method, dubbed 4U Lighting. A human-subjects study was conducted in which 12 participants 65 or older observed pedestrians under different lighting configurations and identified the moment when they were sure they could see a pedestrian. The participants drove a vehicle towards a static vehicle in the opposite lane around which the pedestrians were located. The distance at which participants could detect the pedestrian, termed the detection distance, was compared across lighting conditions and served as the measure of improvement in driver visual performance (visibility). Commercial connected vehicle hardware and protocols were used to communicate position between the two vehicles and to trigger the operation of the custom lighting control system. The system operated as expected and the data showed benefits to driver visual performance.
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    Active and Adaptive Roadway Delineation Systems
    Williams, Brian M.; Gibbons, Ronald B.; Flintsch, Alejandra Medina (National Surface Transportation Safety Center for Excellence, 2017-10-13)
    Heavy fog presents a significant safety hazard to drivers by reducing their ability to see the roadway and other vehicles. Even so, drivers often fail to adjust their speed to account for the reduced visibility, resulting in stopping distances that exceed visibility distance. Active delineators, or in-pavement light emitting diode (LED) markers, are an emerging technology which can be used to assist drivers in traveling through fog-prone areas by marking road or lane boundaries. However, there is a lack of research indicating how the presence of active delineators might also affect a driver’s behavior. This study sought to examine how the presence of active delineators in fog might affect drivers’ speed. Three lighting patterns and two brightness levels were tested. In daytime conditions, the delineators had no effect on speed. During nighttime conditions, participants often drove faster when the active delineators were present. Participants felt that the active delineators were helpful for navigating through the fog in both daytime and nighttime conditions, but preferred the higher brightness settings in the daytime.
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    Analyzing Intersection Gap Acceptance Behavior with Naturalistic Driving Data
    Li, Yingfeng (Eric); Hao, Haiyan; Gibbons, Ronald B.; Medina, Alejandra (National Surface Transportation Safety Center for Excellence, 2022-09-14)
    Safety at unsignalized intersections continues to be a major concern for transportation agencies and roadway users. To improve intersection safety, this project conducted a comprehensive study of gap acceptance behaviors at unsignalized intersections using the second Strategic Highway Research Program (SHRP 2) naturalistic driving study (NDS) data. The team collected 1,170 accepted and rejected gaps/lags based on 466 NDS trips at 60 unsignalized T-intersections in Washington state and North Carolina. The project team utilized a number of data sources, including time series data measuring vehicle kinematics for the analyzed trips, forward-facing and rear-view videos for the analyzed trips, driver demographic and driving history data, the SHRP 2 Roadway Information Database, and satellite images. First, the team identified the critical gaps for a number of common scenarios using three widely accepted methods: binary logistic regression, maximum likelihood method, and probability equilibrium method. Results showed an overall critical gap of 5.3 seconds for right-turning trips and 6.2 seconds for left-turning trips. The team then went on to develop a complete understanding of the factors affecting gap acceptance decisions using logistic regression and machine learning techniques. A number of factors were identified that affect drivers’ gap acceptance decisions, including being a gap instead of a lag, presence of leading and/or following vehicles, higher volume, intersection being unskewed, and increased number of through lanes. Finally, researchers further investigated drivers’ longitudinal and lateral acceleration behaviors during turning after accepting a gap and factors affecting their turning behaviors. Overall, both left- and right-turning vehicles initially accelerated quickly after they accepted a gap, and then reduced to a lower but prolonged acceleration rate while turning to reach a desired speed. For lateral acceleration, the peak value for the left-turning profile was reached later in the turning process than for the right-turning profile.
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    Applicability of mesopic factors to the driving task
    Gibbons, Ronald B.; Terry, Travis N.; Bhagavathula, Rajaram; Meyer, Jason E.; Lewis, A. (SAGE, 2016-02-01)
    With the advent of light-emitting diode technology being applied to roadway lighting, the spectral power distribution of the light source is becoming much more important. In this experiment, the detection of pedestrians at five adaptation levels under three light sources, high pressure sodium and light emitting diodes of two colour temperatures was measured in realistic roadway scenarios. The results show that while the light source type was not significant, an increase in adaptation luminance increased the detection distance. As the offset of the object to the roadway increased, some spectral effects became more significant; however, this effect was not consistent across all angles of eccentricity. The conclusions from this work indicate that mesopic factors may not be applicable on high-speed roads.
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    Assessing the Safety Impact of Roadway Improvements Using Naturalistic Driving Data--Feasibility Study
    Li, Yingfeng; Medina, Alejandra; Gibbons, Ronald B. (National Surface Transportation Safety Center for Excellence, 2017-10-19)
    This project explored the feasibility of using Second Strategic Highway Research Program (SHRP 2) data, including the Roadway Information Database (RID), to evaluate the effectiveness of roadway safety improvements where traditional crash data are limited. The research team conducted two case studies based on naturalistic driving study (NDS) data from 200 trips. The two case studies evaluated the safety effects of (1) a paving project with newly installed pavement and markings, and (2) a median barrier replacement project with a newly installed and restored concrete median. A number of safety surrogate measures were used to develop a comprehensive understanding of how driver behavior changed with and without the safety treatment. The results from both case studies indicated that the roadway improvements had an impact on driver safety behavior, as indicated through the surrogate safety measures of speed, lateral and longitudinal accelerations, lane deviation, and car-following behavior. The two case studies illustrate two different methods for studying the effectiveness of roadway improvements on safety. The paving project case study compared driver behavior data collected at the project site after the roadway improvement with data from an adjacent site with similar roadway conditions but without the pavement improvement. The median barrier project case study compared data on the same segment of road before and after the improvement project. The two different methods illustrate the flexibility available with SHRP 2 safety data. In addition to the case studies, the research team also assessed the availability, suitability, and limitations of SHRP 2 and RID data for evaluating the safety impact of roadway improvements.
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    The Assessment of Alternative Overhead Sign Lighting
    Williams, Brian M.; Gibbons, Ronald B. (National Surface Transportation Safety Center for Excellence, 2020-07-22)
    This report evaluates an alternative method for lighting highway signs that takes advantage of their retroreflective properties. This method uses a single luminaire mounted some distance upstream of the sign, with a focused, but evenly distributed beam so that the sign always receives the same amount of illumination. To evaluate the proposed system, a human-subjects experiment was performed on the Virginia Smart Road to test two sign configurations: an overhead sign mounted on a gantry above the highway and a sign mounted at the side of the road on a horizontal curve. For the overhead sign, there were no statistical differences between the upstream lighting, traditional style lighting, and headlamp-only conditions, though there was an increase in the mean legibility distance of the sign (~14 m) when the upstream luminaire was located on the shoulder of the road at the highest luminance setting. For the horizontal curve, upstream lighting provided no benefit for sign legibility due to the ambient lighting in the vicinity, but placing the luminaire closer to the sign (approximately 20 m) resulted in more consistent luminance from a wider range of viewing angles. Although upstream lighting provided legibility distances similar to traditional sign lighting, it may offer advantages due to reduced maintenance and energy costs.
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    The Assessment of New Roadway Lighting in Rain and Fog
    Williams, Brian; Gibbons, Ronald B. (National Surface Transportation Safety Center for Excellence, 2022-10-27)
    This study sought to determine if different types of roadway lighting performed differently in rain or fog. The performance of the lighting was determined by participants’ ability to detect different objects along the shoulder of the road as they drove an experimental vehicle through simulated rain and fog at night on the Virginia Smart Roads Highway. Twenty-seven participants took part in this study, which consisted of three sessions: one for consenting and screening, one for performing the study in clear weather, and one for performing the study in rain and fog conditions.. As participants drove along the Smart Roads Highway, they looked for and verbally identified two types of objects that appeared on the right shoulder of the road. These included pedestrians wearing red, blue, or gray clothing, or small 7-inch square wooden targets painted red, blue, or gray. Participants also identified the color of the object. Participants performed these tasks under three different types of roadway lighting: traditional high-pressure sodium (HPS) lamps and two types of light-emitting diode (LED) lamps with different color temperatures (3500K and 6000K). Presentation orders of the lights and objects were counter-balanced to reduce learning effects. The performance of each light was determined by the distance at which participants could identify objects (detection distance) and the distance at which they could recognize the color of the objects (recognition distance). For each object and weather condition, a 2 (age) × 3 (lighting) × 3 (color) analysis of variance (ANOVA) was conducted with an alpha of 0.05. No significant difference was found among light types on participants’ ability to detect pedestrians in any weather condition. Results showed that all three light types performed equally for the detection of pedestrians in all weather conditions and for the detection of targets in clear and fog conditions. A significant difference was only found for the detection of targets in rain. However, there was no clear best performer as each light type performed well for the detection of some colors of targets and poorly for others. On average, detection distances for targets in the rain were approximately 10 m longer under the LED lights compared to the HPS.
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    Assessment of the Durability of Wet Night Visible Pavement Markings: Wet Visibility Project Phase IV
    Gibbons, Ronald B.; Williams, Brian M. (Virginia Center for Transportation Innovation and Research, 2012-06)
    This project encompassed a research effort to establish the durability of pavement markings in an on-road installation. Six marking technologies were installed on a portion of Route 460 in Blacksburg, Virginia. A human factors experiment in natural rain conditions was performed to establish the visibility needs of the driver. The retroreflectivity of the markings was measured at intervals of 2 to 5 months, with six measurements over the course of 23 months. The numbers of snow plow crossings and chemical treatments were also measured. Although all markings lost a considerable amount of retroreflectivity after the first winter, the markings installed in grooves or in rumble strips were shown to retain more retroreflectivity and receive less damage than markings installed on the surface of the roadway. Twenty-three months after installation, the retroreflectivity for all markings in active rain conditions had dropped below the 150 mcd/m2/lx minimum recommended from previous research. The reflective tape was the closest to maintaining the minimum with a mean retroreflectivity of 137mcd/m2/lx in 1 in/hr rain. Several other markings maintained a retroreflectivity above 84 mcd/m2/lx; this may still provide a benefit over standard paint. The study recommends that VDOT's Traffic Engineering Division install pavement markings in grooves or in rumble strips. VDOT will determine where the use of grooves or rumble strips is appropriate. Because pavement marking visibility is more critical for high-speed roadways such as interstate roadways and major arterials, these roads should be the highest priority. Grooved markings may also be desired for high-volume roadways where markings may be exposed to higher levels of wear from traffic. The study markings on Route 460 in Blacksburg should be monitored for two more years. The study team should make the measurements after each winter through 2013 and report the findings to VDOT in a brief report. VDOT staff should perform additional cost-benefit analyses to address standard VDOT policy, procedures, and practices and possible supplier warranties.
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    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.
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    Assessment of the impact of color contrast in the detection and recognition of objects in a road environment: final report
    Terry, Travis N.; Gibbons, Ronald B. (National Surface Transportation Safety Center for Excellence, 2011-12-16)
    With the development of new light sources, options for the color and spectral output of a luminaire are wider than for traditional light sources. This can impact visibility as the spectral output of a light source may have a significant impact on the appearance of objects in the roadway environment. This study compares the visibility and color contrast afforded by three separate roadway luminaire types, each with a different spectral output. The benefit provided by the additional color information provided by the spectral distribution of a luminaire can improve detection of objects in the roadway by as much as 50%. These results, however, are not consistent across all spectral output and object color combinations. These results also indicate that the proper selection of a luminaire output will provide better visibility for the driver. -- Report website.
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    Assessment of the Performance of Light-Emitting Diode Roadway Lighting Technology
    Gibbons, Ronald B.; Li, Yingfeng; Meyer, Jason E. (Virginia Transportation Research Council, 2015-10)
    This study, championed by the Virginia Department of Transportation (VDOT) Traffic Engineering Division, involved a thorough investigation of light-emitting diode (LED) roadway lighting technology by testing six types of roadway luminaires (including housing and all components enclosed) in a laboratory environment and on the field over a 2-year period. The results showed that LED luminaires exhibited superior lighting and related qualities compared to high-pressure sodium luminaires. Different photometric characteristics were found among LED luminaires of different designs, indicating a careful selection considering light distribution and illuminance level is necessary for individual lighting applications. During the first 2 years of operation, the average light loss for the LED luminaires was 6% based on laboratory testing. The study also found that implementing LED technology systematically will result in a return on investment between 3.25 and 5.76 for different scenarios over a 25-year period due to savings in maintenance and energy consumption. The study resulted in the VDOT LED Roadway Luminaire Specification document and developed recommendations relevant to VDOT’s implementation of LED technology.
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    Bicycle Visibility: Conspicuity of Bicycle Headlamps, Tail Lamps, and Retroreflective Garments in Nighttime Roadway Environments
    Bhagavathula, Rajaram; Gibbons, Ronald B.; Williams, Brian M.; Connell, Caroline A. (National Surface Transportation Safety Center for Excellence, 2020-07-21)
    Cyclist deaths are overrepresented among traffic fatalities, and increasing cyclist conspicuity to drivers could potentially reduce cyclist deaths, particularly at night. This report describes an experiment with various commercially available bicycle visibility-enhancement systems in terms of their conspicuity to drivers during the day and at night. Visibility enhancements included a headlamp, tail lamp, spoke lights, and retroreflective clothing, including garments that highlight biomotion. The results indicate that active visibility treatments, such as bicycle-mounted lights, make cyclists more conspicuous than passive systems like retroreflective vests and biomotion bands. Flashing headlamps and tail lamps were the most conspicuous treatments during both the day and at night; fast flashing headlamps (6.7 Hz) had higher detection distances and rates during the day, and moderately fast flashing headlamps (3.4 Hz) had higher detection distances and rates at night. Spoke lights and flashing tail lamps, along with retroreflective vests, also aided cyclist visibility during the day and at night, especially for vehicles approaching intersecting cyclists. Passive retroreflective visibility treatments were most effective at night, when the vehicle was passing the cyclist from behind. However, that approach also used reflectors, so the discrete effect of passive retroreflective treatments could not be determined. This study also found that biomotion markers alone do not significantly increase cyclist conspicuity in visually complex natural environments. For most approaches, flashing lights had greater detection distances than biomotion markers, which in turn had higher detection rates than headlamps and tail lamps.
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    Color Camera
    Meyer, Jason E.; Gibbons, Ronald B.; Connell, Caroline A. (National Surface Transportation Safety Center for Excellence, 2017-02-28)
    Under the sponsorship of the National Surface Transportation Safety Center for Excellence (NSTSCE), a research team at the Virginia Tech Transportation Institute (VTTI) developed a color camera system that can collect naturalistic video data with accurate color rendering. Photometric devices can accurately measure color but cannot record the video data necessary for understanding visibility in dynamic environments like nighttime driving. Video recorders can take video data but are inaccurate with respect to color measurement. To measure color and its effects on visibility in naturalistic settings, a color camera system was developed that can record video data with color rendering similar to what humans perceive. This system includes a calibrated color camera and image analysis software. The camera system was selected and calibrated in different lighting scenarios using a standard color chart. Custom MATLAB programs were used for this calibration. These calibration files were compared for color-rendering accuracy, and the best file, based on calibration in daylight, was selected for further analysis. Researchers then used the color camera system, calibrated with the daylight file, to collect data in a variety of naturalistic settings. The color space coordinates from the color camera’s images were compared with those taken with a color meter and a digital photometer. When the camera was calibrated to daylight, it produced the most-accurate images, even when taking images in artificial lighting. Shorter exposure times produced darker images but more-accurate color space coordinates. After calibration and exposure adjustment, the color camera’s chromaticity coordinates (x, y) had about 10% error with respect to the color meter. The color camera’s luminance value (Y) had less than 5% error with respect to the color meter. The calibration file produced can be used with multiple cameras. A new image analysis method was developed. It and its accompanying custom MATLAB programs allow researchers to select portions of an image and analyze their three-dimensional color space coordinates. This capability will be useful in future work; for example, comparing photometric equipment, and analyzing naturalistic video data.
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    Comparing LED Lighting Systems in the Detection and Color Recognition of Roadway Objects
    Terry, Travis N. (Virginia Tech, 2011-05-11)
    This study compared two LED luminaires and their abilities to provide detection distance and color recognition distance of potential roadway hazard. Detection distance is regarded as a metric of visibility. Color recognition distance is a metric for comparing the impact of the (Correlated Color Temperature) CCT of each luminaire and their color contrast impact. Mesopic vision, the mode of vision most commonly used for night driving, was considered in this study. Off-axis objects were presented to participants to assess the peripheral abilities of the luminaires. The impacts of luminance and color contrast were addressed in this study. The experiment was performed on the Virginia Smart Road where standard objects of different colors and pedestrians wearing different colors were detected by drivers of a moving vehicle in a controlled environment. The key difference between the two luminaires was their color temperatures (3500K versus 6000K). The results indicated that neither light source provided a significant benefit over the other although significant interactions were found among object color, age, and lighting level. The results indicate that the luminaires provide similar luminance contrast but their color contrasts depend heavily on the color temperature, the object, and the observer. This study followed the protocol developed by the Mesopic Optimisation of Visual Efficiency (MOVE) consortium developed by the CIE for modeling mesopic visual behavior.
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    Connected Vehicle Applications for Adaptive Overhead Lighting (On-demand Lighting)
    Gibbons, Ronald B.; Palmer, Matthew; Jahangiri, Arash (Connected Vehicle/Infrastructure University Transportation Center (CVI-UTC), 2016-07-01)
    The Virginia Tech Transportation Institute (VTTI) has developed an on-demand roadway lighting system and has tested the system’s effect on driver visual performance. On-demand roadway lighting can dramatically reduce energy usage while maintaining or increasing vehicle and pedestrian safety. The system developed by VTTI uses connected vehicle technology (CVT), wireless lighting controls, LED luminaires, and a stand-alone processor on the Virginia Smart Road to sense vehicles and turn on roadway lighting only when needed. During this research project, the use of on-demand, or just-in-time, lighting was investigated with respect to assessing driver distraction, and to human factors, including a driver’s ability to visually detect and recognize on-road objects and pedestrians. The developed on-demand lighting system described above utilized dedicated short range communication (DSRC), connected vehicle infrastructure (CVI), and centralized wireless lighting controls, and was used with VTTI-developed in-vehicle instrumentation and custom software. The software allowed the study of forward preview time in terms of forward lighting distance needed for drivers to detect roadside pedestrians and hazards. Visual performance testing revealed a relationship between speed and the amount of forward lighting needed to detect pedestrians and hazards on the side of the roadway, and a small, but statistically insignificant, practical difference in visual performance between on-demand lighting and continuously-on lighting conditions. A survey of participant reactions indicated that the public generally accepts on-demand lighting and does not find it distracting as long as a minimum lighting condition is met. The survey also found that participants felt the system provided a safe driving environment. The main application for an on-demand lighting system would be on roadways with little traffic at night and higher accident rates, or higher conflict areas such as intersections, pedestrian crossings, and merge areas.
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    Credibility of a Person-Centered Design Decision-making Prototype: Spaces for Older Persons with Vision Loss
    Gowda, Vidya (Virginia Tech, 2016-06-29)
    Decline in both visual acuity and visual performance is a fact of life for older people and their increasing share of the population requires that buildings be designed with their visual needs in mind. As their field of vision decreases, people find it harder to identify an objects location, distance, and orientation. Elderly people with vision impairments usually find it harder to perform daily activities such as navigation through indoor spaces. Functional vision can be improved by modifying the design of spaces, for example, with better lighting. However, architects typically do not know how to take the needs of the visually impaired into account in their design process, or simply do not think of doing so. The researcher designed and feasibility-tested a prototype person-centered tool to help architects judge how appropriate a designed space will be for visually impaired people. The study was conducted as a qualitative mixed-methodology research analysis. The researcher used knowledge from literature interpretation to rationalize the development of a person-centered prototype. The researcher immersed design PhD students and vision science experts to inform the prototyping process. Along with an expert group of design and vision science professionals, the researcher beta-tested the prototype during a mock design-process scenario. The researcher also selected a small group of industry experts to participate in open-ended interviews on post-use demonstrations to qualitatively triangulate the findings on the prototypes usability. The study summarizes the feasibility including the challenges of using the prototype for professional purposes and suggests improvement.
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    Development and Testing of an Integrated, Versatile, Bicycle-Based Data Acquisition System
    Owens, Justin M.; Alden, Andrew; Antin, Jonathan F.; Gibbons, Ronald B. (National Surface Transportation Safety Center for Excellence, 2022-09-27)
    The goal of this study was to develop and demonstrate the effectiveness of a novel bicycle data acquisition system (bikeDAS) to extend the Virginia Tech Transportation Institute’s expertise in instrumentation and naturalistic data collection into the realm of bicycles and other fully or partly human-powered vehicles. The methodology incorporated the identification of a series of design considerations for effective bicycle instrumentation, including weight and balance, power, data collection capability, and mount location and design. These were addressed in a series of prototype iterations, each of which included testing in on-road situations to determine areas for improvement. The final VTTI bikeDAS is based on a weatherproofed version of the VTTI MiniDAS. The MiniDAS was developed as a low-cost, self-contained data acquisition system (DAS) for use in automobiles and motorcycles and has been adapted for use on bicycles with the addition of a rechargeable battery pack that looks and mounts to the frame like a standard water bottle. It consists of a single main unit measuring approximately 165 mm by 133 mm that contains two video cameras and numerous sensors, including GPS and a multi-axis inertial measurement unit (IMU). A mounting system has been developed to allow flexibility of placement across different types of bicycles; the typical location is attached to the head tube, which allows an unobstructed forward view, as well as views of the rider’s face and hands, and approaching vehicles, depending on bicycle geometry. This report provides detail about the needs analysis, prototyping, development, and deployment phases, and discusses areas of future development and research.
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    Development and validation of a luminance camera: final report
    Meyer, Jason E.; Gibbons, Ronald B.; Edwards, Christopher J. (National Surface Transportation Safety Center for Excellence, 2009-02-11)
    Under the sponsorship of the National Surface Transportation Safety Center for Excellence (NSTSCE), an effort was undertaken to develop a system of image capture to analyze luminance data gathered in naturalistic driving research.
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    Development of a Mobile Measurement System for Roadway Lighting
    Gibbons, Ronald B.; Meyer, Jason E.; Edwards, Christopher J. (National Surface Transportation Safety Center for Excellence, 2018-01-04)
    In recent years, the complexity of the evaluation metrics of roadway lighting has continually increased. In order to measure the effectiveness of a roadway lighting system in situ, a mobile measurement system has been developed to provide evaluations of illuminance, luminance, spectral content, glare, human visibility performance, and vehicle condition. This system, the Roadway Lighting Mobile Measurement System (RLMMS), has been developed to be transportable to anywhere in the world and mounted on any vehicle. The RLMMS consists of five illuminance meters: four measure the centerline and wheel path illuminance of the vehicle and the fifth measures the illuminance at the eye of the driver. The system also uses two cameras: the first a calibrated luminance camera and the second a color camera for scene evaluation. The RLMMS is able to tie into the internal vehicle network to obtain speed and distance measurements. Additional tools, such as a spectroradiometer and an eye tracker, have also been incorporated into the system. Finally, as a method of evaluating human response, the RLMMS includes buttons that allow users to place response markers in the data stream. The repeatability and reproducibility of the system was evaluated, and comparisons were made to the traditional handheld method of measuring illuminance. Results indicate that the system’s measurement of illuminance may be considered acceptable. The entire system has been programmed in LabView and allows for a variety of configurations of data collection. The system has been utilized in several research projects, including some in Anchorage, Alaska; Honolulu, Hawaii; and San Diego, California.
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    Development of a Nighttime Visual Performance Model by Examining Distributions of Detection Distances
    Bhagavathula, Rajaram; Gibbons, Ronald B. (2023-12-22)
    Modeling the visual performance of drivers at night is complex. In addition to factors like luminance, contrast, observer age, and object size, research has shown that the motion of the object and the expectancy of the observer play an important role in the observer’s ability to detect an object on the roadway at night. Thus, it is important for a visual performance model to account for these factors. However, accounting for these factors could result in highly complex models, as accurately measuring driver expectancy and attention is difficult. A probabilistic approach to modeling nighttime driver visual performance could offer promise. In a probabilistic modeling approach, the variable of interest is treated as a random variable and the probability distribution of this variable is studied as a response to different conditions. In the case of night driving, we propose to use the detection distance of an object (such as a pedestrian) as the variable of interest. Detection distance is a measure of the reaction time of the driver. By studying the distribution of detection distances of objects under different lighting conditions, we can accurately understand the change in the detection probability of an object as a driver approaches an object. The current report had two goals. The first goal was to test if the detection distance distributions are accurately defined by the Weibull distribution. The second goal was to understand how different light levels affect the detection distance distributions of a child-sized mannequin. This was accomplished by performing a distribution analysis involving fitting a Weibull distribution to the detection distance data. The distribution fit will indicate how parameters like shape and scale vary across different conditions and their practical impacts on driver visual performance. The results of the study showed that the Weibull distribution could be used to fit the detection distance data, and that changing the light level definitely influenced the parameters of the distribution. An increase in light level increased the scale parameter and caused the detection distance distribution to stretch out from the pedestrian’s location. The results of the study also showed that both the scale and shape parameters could be used to compare the effectiveness of different lighting systems or interventions. The survivor functions of the detection distance data from the fitted Weibull distribution could be used to compare the effectiveness of a lighting system or a countermeasure by calculating the percentage of the population that detected the pedestrian from a distance greater than the stopping sight distance.