Assessment and modeling of the glare induced by tungsten-halogen and high intensity gas discharge headlamps

High Intensity Gas Discharge (HID) headlamp glare was investigated in a two part study, and a model was developed based on the findings. First part of this study investigated the effect of headlamp glare on driver eye fixation patterns under four different headlamp glare conditions in the field. Headlamp glare was administered by vehicles equipped with projector-type headlamps, staged to execute glare encounters with unsuspected drivers on straight and level, two-lane roadways. The four headlamp conditions were, typical HID, neutral-density filtered HID (NDHID), Tungsten-Halogen (TH), and TH with blue daytime conversion filters. The luminous intensity of the HID headlamps was reduced to the TH headlamp intensity levels, and the color of the blue filtered TH headlamp (BFTH) was very similar to that of the HID headlamps. This way, the intensity and the spectral power distribution (SPD) of the headlamps were systematically investigated. The effect of beam pattern was minimized by selecting similar beam patterns. The second part of the study investigated the disability glare caused by the four headlamp types, while driving the same four types of HID and TH equipped vehicles. Pedestrian detection distances were obtained as a dependent measure. Discomfort glare ratings for all four headlamp conditions were also obtained in a static setting using the DeBoer scale. Finally, a lambertian surface detection module, and an eye-fixation estimation module was developed for the enhanced visibility model TarVIP. The lambertian surface module was calibrated using the pedestrian detection distance data, and a glare evaluation module was developed and validated. The analysis shows that the average headlamp illuminance at driver eye during an encounter was the most prominent factor affecting the number of eye fixations, whereas the SPD had a minimal effect. The differences in the disabling effects of any of the four headlamp conditions were not statistically significantly at α = 0.05. However, the detection distances under any of the four headlamp glare conditions were different than the no glare condition. HID headlamps provided farther detection distances than the TH headlamps. The differences in the discomfort glare ratings for the four headlamp glare conditions were not statistically significant.