Suway, J. and Welcher, J., "Retroreflective DOT-C2 Tape Performance in Relation to Observation and Entrance Angle - A Real World Study," SAE Technical Paper 2015-01-1432, 2015, doi:10.4271/2015-01-1432.
Accident reconstruction experts are often asked to evaluate the visibility and conspicuity of objects in the roadway. It is common for objects placed in or along the roadway, vehicles, and required by Federal Motor Vehicle Safety Standard (FMVSS) No. 108 for certain vehicles and trailers, to have red and white DOT-C2 retroreflective tape installed on several locations. Retroreflective tape is designed to reflect light back towards the light source at the same entrance angle. The authors' literature review revealed that there have been no publications quantifying the performance of commercially available DOT-C2 retroreflective tape with real world vehicles. Therefore, without additional study, an accident reconstruction expert cannot know exactly how a specific type of compliant tape would perform beyond the minimum federal requirements. In the current research, the performance of white and red DOT-C2 retroreflective tape is quantified. Using different vehicles, with differing headlight housings, bulb types, headlight height, occupant seating height, and headlight spacing, the performance of different types and manufacturers of retroreflective tape was quantified at different entrance angles. The authors attempted to study a range of popular, commercially available, DOT-C2 retroreflective tape. In this study, 3M 963, 3M 983, Grote, and Trucklite DOT-C2 retroreflective tape were used. The effect of change in observation angle and entrance angle were studied. Preliminary research was performed on the effect of measuring luminance through a vehicles windshield, which has factory tinting, versus outside of the vehicle, not through the windshield. From the current study, it was determined that the entrance angle and the observation angle affected the performance of all of the retroreflective tapes, with lower performance at higher entrance angles and/or observation angles. It was also determined that the white retroreflective tape had higher performance than the red retroreflective tape for every tape type tested. Finally, it was determined that the performance of the tape decreased when measured through the windshield of the vehicle, versus from outside of the vehicle.