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Abstract
Adrian's Visibility Model is a useful tool for assessing the visibility of an object at night. However, it was developed using test data under laboratory conditions. Thus, it is necessary to determine the visibility levels which are required for target detection under nighttime driving conditions. The author has previously presented a study in which experimental data from Olson and others were applied to the Adrian Visibility Model to determine visibility levels at target detection for alerted and unalerted drivers. However, a limitation in the model's handling of glare (valid for 1.5° to 30°) limited the useable data. A modified Visibility Model is proposed which incorporates the CIE General Disability Glare Equation. This widens the available glare range to 0.1° to 100° and allows for a more robust analysis than had been presented previously. Age, headlight beam pattern, and target reflectivity were all found to have a significant effect on visibility level at target detection for alerted drivers. Target size and position did not significantly affect visibility level at target detection. Average threshold visibility levels between 0.1 and 18 were calculated for alerted drivers. For unalerted drivers, average threshold visibility levels between 14 and 89 were calculated.
