Visibility of Tractor Trailer Reflective Strips at Small Viewing Angles in Collision Reconstruction

Abstract

In collision reconstruction of nighttime accidents, the conspicuity of hazards from a driver's perspective is a critical factor. When the collision involves large commercial vehicles, the visibility of the reflective strips is essential in assessing avoidance. Reflective strips on commercial vehicles are generally consistent from vehicle to vehicle and are highly reflective between perpendicular and 45° viewing angles. However, at shallower viewing angles (closer to parallel viewing), which occurs when trailers begin turns, the reflective strips may not be effective. In this initial study, the effectiveness of reflective strips at shallow viewing angles (‘entrance angles’ of 45° to 90°) was examined under a variety of test conditions including high beams and viewing distances of up to 150 m. The results indicated that at entrance angles of less than 70°, reflective strips are highly effective warnings from a human factors perspective. At entrance angles of more than 75°, reflective strips are ineffective. From 70° to 75°, the results were sensitive to the test parameters. This study does not address the visibility of the tractor or other aspects of nighttime visibility. Further research is recommended to extend this study to greater viewing distances, xenon headlights, ‘dirty’ vs. ‘cleaned’ reflective strips, and wet roads, with particular attention to entrance angles of 70° to 75°.