IMPACT OF USING LIGHT EMITTING DIODES (LEDS) ON RECOGNITION OF COLORED LIGHT SIGNALS BY COLOR VISION DEFICIENT DRIVERS

Traffic signals must provide a conspicuous signal to a wide variety of drivers over a broad range of environmental and geometric conditions. The incandescent traffic signal, developed from existing maritime and railroad signaling systems, was a compromise between luminous efficiency and color saturation. While higher color saturation might result in an improved recognition level, with incandescent systems it also results in a lower intensity--which decreases detection and recognition distances. The use of direct-emitting sources may allow for rejection of such compromises. This paper evaluates the impact of using Light Emitting Diodes (LEDs) as the source for traffic signals, on drivers with color vision deficiency. While traffic lights are presented at suprathreshold levels, much of this work is pertinent to other forms of transport signaling, including lights producing a far lower illuminance at the observer's eye.