Ashley Stafford Sewall

Electroluminescent materials can further enhance the nighttime conspicuity of pedestrians wearing retroreflective materials

Objective: We investigated the nighttime conspicuity benefits of adding electroluminescent (EL) panels to pedestrian clothing that contains retroreflective elements. Background: Researchers have repeatedly documented that pedestrians are too often not sufficiently conspicuous to drivers at night and that retroreflective materials can enhance the conspicuity of pedestrians. However, because retroreflective elements in clothing are effective only when they are illuminated by the headlamps of an approaching driver, they are not useful for pedestrians who are positioned outside the beam pattern of an approaching vehicle’s headlamps. Electroluminescent materials—flexible luminous panels that can be attached to clothing—have the potential to be well suited for these conditions. Method: Using an open-road course at night, we compared the distances at which observers responded to pedestrians who were positioned at one of three lateral positions (relative to the vehicle’s path) wearing one of two high-visibility garments. Results: The garment that included both EL and retroreflective materials yielded longer response distances than the retroreflective-only garment. This effect was particularly strong when the test pedestrian was positioned farthest outside of the area illuminated by headlamps. Conclusion: These findings suggest that EL materials can further enhance the conspicuity of pedestrians who are wearing retroreflective materials. Application: EL materials can be applied to garments. They may be especially valuable to enhance the conspicuity of roadway workers, emergency responders, and traffic control officers.

Observers’ Judgments of the Effects of Glare on Their Visual Acuity for High and Low Contrast Stimuli:

Disability glare refers to a reduction in the ability to discern a stimulus that is positioned near another stimulus that has a much higher luminance. While it is common for drivers to report that they have been “blinded” by oncoming headlights, it is unclear whether observers can accurately judge when they are visually disabled by glare. This experiment sought to quantify the accuracy with which observers can judge when a glare source reduces their visual acuity. Seventeen observers estimated their disability glare threshold (DGT)—the luminance of a glare source that would be just sufficient to impair their ability to discern the orientation of a Landolt C that was surrounded by the glare source. These estimated DGTs were compared to the participant’s actual DGTs. Participants consistently underestimated the intensity of glare that was required to impair their acuity. On average, estimates of glare threshold were 88% lower than actual glare threshold intensities. Participants’ judgments were affected by stimulus size but not stimulus contrast. These results suggest that observers can exaggerate the debilitating effects of glare and that they can fail to appreciate that high contrast stimuli are more robust to glare. A driver who believes that even the lowest intensities of headlight glare can visually impair an oncoming driver may be reluctant to use high beam headlamps, despite their significant visibility advantages.

Effects of an Educational Intervention on Athletes’ Attitudes Toward Wearing Conspicuity-Enhancing Garments at Night

Most vehicle-into-pedestrian fatalities occur at night, and insufficient conspicuity of pedestrians’ clothing is a key causal factor. Marking pedestrians with retroreflective material can dramatically enhance their nighttime conspicuity, particularly when it is configured to present biological motion information to drivers. Although those who exercise outdoors at night are at particular risk and are therefore a key target audience for conspicuity-enhancing clothing, their willingness to obtain and use conspicuity aids has not been explored systematically. There is, however, evidence to suggest that pedestrians fail to appreciate visibility problems at night (e.g., typical pedestrians overestimate their own visibility and underestimate the benefits of wearing conspicuity-enhancing clothing.) The purpose of the current project was to measure the impact of an educational intervention on relevant attitudes of a sample of frequent outdoor exercisers. Results suggest that prior to the educational intervention the participants appreciated neither the magnitude of the nighttime conspicuity problem nor the benefits of biological motion configurations. We also found that a carefully designed lecture can result in a significantly improved understanding of nighttime conspicuity issues and a greater interest in (and willingness to purchase) conspicuity-enhancing athletic garments. The findings from this study are expected to be useful for encouraging pedestrians to take steps to enhance their own conspicuity at night.

Drivers’ Beliefs, Habits, and Strategies Regarding High Beam Usage

Research suggests that drivers do not fully understand the visual challenges they face when driving at night, and that drivers typically under-use their high beams. Because little is known about what factors influence drivers’ usage of high beams, this study surveyed 202 undergraduates concerning their beliefs, habits, and strategies in choosing beam settings. Participants completed a 29-question survey asking about their general understanding of headlamp usage and roadway safety. These data reflect what drivers learned about beam usage when they were taught to drive and describe the factors that influence drivers’ selection of high and low beams. The data also describe the participants’ estimates of the frequency with which they use high beams, and quantify drivers’ estimates of the distance at which they can see different objects at night. These data offer insight into drivers’ beliefs about headlights, night vision, and safety. These insights are expected to be useful when designing educational interventions to encourage appropriate usage of high beams.

Electroluminescent Materials Can Improve Nighttime Pedestrian Conspicuity When Added to Retroreflective Garments

Retroreflective materials make nighttime pedestrians more conspicuous to drivers, especially when configured in a biological motion pattern. Because retroreflectors are only effective when they are illuminated by a light source near the driver, they are not useful for pedestrians who are positioned outside the beam of a vehicle’s headlamps. Electroluminescent materials have the potential to enhance conspicuity in these conditions. We investigated the conspicuity benefits of adding electroluminescent material to clothing containing retroreflectors. We compared, using an open-road course at night, the distances at which 120 observers responded to a test pedestrian wearing one of two garments at one of three roadside locations. Response distances to the garment that contained both electroluminescent and retroreflective materials were significantly longer, particularly when the pedestrian was more poorly illuminated as a result of being positioned on the left shoulder. These findings suggest electroluminescent materials have the potential to enhance the conspicuity of pedestrians.

Pedestrians’ Willingness to Seek Out, Purchase, and Wear Conspicuity-Enhancing Athletic Garments

Most traffic-related pedestrian fatalities occur at night, and insufficient conspicuity of pedestrians’ clothing is recognized to be a key causal factor. In an effort to explore the demand for conspicuity-enhancing garments we examined the attitudes of 166 university students about nighttime conspicuity problems and their interest in (and willingness to purchase) these clothing items. We found that when it comes to their own conspicuity at night pedestrians are too often overconfident and uninformed. Participants generally believed that wearing brightly colored clothing or a reflective vest made them visible to drivers at night and generally did not believe that wearing reflective markings on their ankles and wrists would make them more visible than a reflective vest. Despite having reported that visibility issues were usually not important factors when purchasing athletic garments, most participants reported being willing to pay slightly more for athletic garments (shorts, shirts/jackets, and shoes) that contain reflective markings.