Suway, J. and Welcher, J., "Quantifying Retroreflective DOT-C2 Tape Performance using a Retroreflectometer," SAE Technical Paper 2015-01-1429, 2015, doi:10.4271/2015-01-1429.
Federal Motor Vehicle Safety Standard (FMVSS) No. 108 has minimum performance requirements for retroreflective tape at different entrance and observation angles. In the author's preliminary research, all DOT-C2 retroreflective tape on the market is advertised as meeting and exceeding FMVSS No. 108 requirements. The authors' literature review revealed that there have been no publications quantifying the performance of commercially available DOT-C2 retroreflective tape across a wide range of entrance and observation angles. Therefore, without additional study, an accident reconstruction expert cannot know exactly how a specific type of compliant tape may perform, beyond the minimum federal requirements. In an attempt to solve this issue, the authors have quantified the performance of different types of retroreflective tape with a retroreflectometer. The authors attempted to study a range of popular, commercially available, DOT-C2 retroreflective tape. 3M 963, 3M 983, Grote, and Trucklite DOT-C2 retroreflective tape was studied. A RoadVista 932 handheld retroreflectometer was used to measure entrance angles of 0, 4, 10, 20, 30, and 45 degrees with observation angles from 0.2 to 2.0 degrees at 0.1 degree increments and an additional measurement at 0.33 degrees. As discussed in ASTM E810, each piece of tape was measured at rotation angles of 0 and 90 degrees by rotating the tape about its own retroreflector axis. It was determined that the entrance angle and the observation angle affected the performance of all of the retroreflective tapes, with less performance at higher entrance angles and/or observation angles. It was also determined that the white retroreflective tape had a higher performance than the red retroreflective tape for the tape types tested. Finally, it was determined that the performance of the tape was not symmetric across the tape's retroreflector axis and there was no pattern to the performance determined, for the tape types tested.