Sensitivity Analysis of Headlamp Parameters Affecting Visibility and Glare

Computer-simulated evaluations were conducted to identify the extent to which driver visibility and glare are affected by headlamp light source type (e.g., tungsten-halogen or high-intensity discharge), mounting height, optical system type, alignment type, and mis-aim. Based on the results of these simulation evaluations, this study also addressed whether further limits might be considered in photometric standards for headlamps that are addressed by Federal regulations. While there appears to be an inherent conflict between visibility and glare in the photometric design of headlamps, the analyses performed here do indicate that current photometric specifications for headlamps do not always trade off visibility and glare equally (e.g., headlamps that provide equivalent forward visibility as characterized here can result in different levels of disability or discomfort glare). The findings imply that advanced (dynamic) forward-lighting systems (AFS), if they can be made practical, might be of benefit in adjusting headlamp luminous intensity distributions in various situations to maximize visibility while controlling glare within acceptable limits.