Experimental Studies of Daytime Running Light Design Factors

Data from accident rate field tests have suggested that the use of Daytime Running Lights (DRL) on vehicles may have potential for reduction of collision likelihood and severity. With regard to the possible introduction of DRL in the United States, a number of research and design issues have arisen. These involve effects of design parameters on vehicle conspicuity under daylight conditions including central lamp intensity, beam distribution, lamp area, lamp color, number of lamps, and lamp/background contrast. Experiments were conducted to determine effects of DRL design parameters on peripheral detection of an oncoming vehicle under daylight conditions, detection of operating turn signals in the presence of a masking DRL, and degree of discomfort glare produced by DRL under twilight conditions.