Evolution of an Enhanced Rear Signaling System

Abstract

Rear-end crashes are the most frequently occurring type of crash, making up approximately 25% of all crashes. Crash analysis has revealed a need to detect stopped and slowing lead vehicles with peripheral vision, as well as to detect stopped and slowing lead vehicles with foveal vision more quickly. Two experiments were conducted in an effort to develop systems that have these properties, yet do not have too much discomfort glare. Both experiments used the same four dependent measures: attention-getting rating, discomfort-glare rating, horizontal peripheral detection angle, and diagonal peripheral detection angle. Experiment 1 examined 17 candidate systems, all using white light and clear lenses. The results showed that the TCL, a lamp with a motorized reflector that moves in an M-sweep pattern, was the top candidate for an imminent crash warning signal, while a pair of centrally located alternating halogen lamps would be optimal for a stopped or slowly moving vehicle signal. Experiment 2 examined the effect of colored lenses for the top four configurations identified from Experiment 1. The results showed that TCL is superior to the alternating pair configurations in attention getting and peripheral detection for an imminent crash warning signal, with glare reduced by the use of tinted lenses in either red or amber. The high-output halogen alternating pair with either amber or red dispersive lenses represents the best available configuration for the stopped or slowly moving vehicle signal.