A Comparative Analysis of Electroluminescent and Retrorefelective Materials as Nighttime Pedestrian Conspicuity Aids

Recent literature suggests that retroreflective materials, when configured in a biological motion pattern, make vulnerable road users (such as pedestrians) more conspicuous to drivers at night. However, retroreflective elements in clothing can be effective only when a light source (e.g., automobile headlamps) illuminates the material in such a way as to allow the material to reflect sufficient light back to the eyes of the driver. Thus, retroreflective materials are not useful for pedestrians who are positioned outside the beam pattern of an approaching vehicle's headlamps. Electroluminescent materials, flexible light sources that can be attached to clothing, have the potential to enhance conspicuity in these conditions. This project investigated the conspicuity benefits of adding electroluminescent material to clothing that contains retroreflective elements. Using an open-road course at night, the current work compared the distances at which observers responded to pedestrians wearing one of two different kinds of high-visibility garments, who were at one of three different lateral positions relative to the vehicle's path. The results show that a garment containing both electroluminescent and retroreflective materials yields longer response distances than garments containing only retroreflective material, particularly when the test pedestrian is positioned farther outside of the area illuminated by an automobile's headlamps. These findings suggest electroluminescent materials can be especially useful to enhance the conspicuity of pedestrians who are outside a vehicle's headlamp beam. iii ACKNOWLEDGMENTS I would like to thank my faculty advisor, Dr. Rick Tyrrell, for believing in me and guiding me through this project from its inception to completion. My committee members Dr. have also given me valuable support through this process. I would also like to thank Rudy York for supplying the materials and equipment necessary to complete this project. Finally, I could not have completed this thesis without the hard work and dedication from the other members of the Visual Perception and Performance Lab: