Present and proposed means of coding automobile rear lighting systems were evaluated. Variables considered in study were (1) number of lamps, (2) separation of lamps by function, and (3) colour. Also investigated were intensity and flash rate codes currently in use. Testing was done at night with two specially equipped test vehicles. They were driven both on city streets and on a divided highway to provide city and country conditions. The lead car, equipped with eight rear lighting systems, displayed the test systems, one at a time, to two subjects in a following car. The test subjects (the driver and passenger) in the second vehicle performed a time-sharing task, which required that they respond to turn and stop signals given by the lead car. Their reaction times, the number of missed signals, and subjective ratings were used to evaluate system performance. A total of 66 male and female subjects were used. Results indicate that the rear lighting system concept presently in use provided the poorest performance of all systems tested. Experimental systems show that the arousal property of signals is directly proportional to the number of lamps used. Separation of lamps by function and colour coding of signals were also shown to be factors significantly affecting system performance. The most effective systems were those in which taillights, turn signals, and stop signals were represented by separate lamps. The findings indicate that the light coding techniques represented by the experimental systems (and not currently employed in rear lighting systems) can lead to significant gains in driver performance. /author/.
Abstract