Headlight Glare Resistance and Driver Age

Abstract

The physiological glare thresholds (defined as the logarithm of the ratio at threshold between illuminances of glare source and target background) of 148 subjects from 5 to 91 years of age were measured in a Wolf glare tester. The data can be represented by a power function: (physiological glare threshold) =—3 × 10⁻⁵(age)^2.4 + 2.4. When tested in a realistic driving simulator, the headlight glare resistances (defined as the logarithm of the ratio of mean “acceptable” glare illuminance to fixed ambient illuminance) of 30 of these subjects were also found to decline with age. These results are discussed in in terms of a hypothesis: (headlight glare resistance) = (physiological glare threshold) + (subjective glare tolerance). All these functions have large interpersonal variation. Field measurements are provided on relevant glare ratios in typical night driving situations.