Headlamp Illumination and Glare: An Approach to Predicting Peripheral Visibility

Peripheral visibility is an important aspect of driving but one that is not understood as robustly as on-axis visibility. The present paper summarizes results from a series of field studies investigating the effect of headlamp illumination and of oncoming headlamp glare on the speed and accuracy of response to small targets located in the visual periphery. These experiments used headlamp sets providing differing amounts of illumination on targets of varying reflectance, located throughout the field of view. Reaction times to the onset of targets and the percentage of missed targets were measured. The characteristics and locations of the targets and experimental geometry were similar in each study as were the subject demographic characteristics, so that results were very consistent among each of the studies. The pooled results of these studies make up a set of data from which a model of forward visibility as a function of headlamp illumination, oncoming glare, target reflectance and peripheral angle can be developed. An empirical model is outlined in the present paper with recommendations for future refinements.