Abstract

Objective: On 2-lane roads, discomfort glare can cause annoyance, discomfort, inconvenience, stress, and fatigue to drivers, posing a risk of accidents. The aim of this study is to evaluate discomfort glare from the headlamps of cars widely used in Iran.Methods: The discomfort glare of new vehicles including Pride Saba model GTX, Pride Model 131SL, Samand Soren, Peugeot 405, Megane, and Peugeot Pars was examined at distances of 5 to 100m at a background luminance of 50cd/m(2) (late twilight/early dawn lighting) and 1cd/m(2) (nighttime) using Schmidt-Clausen and Bindels model and de Boer's subjective scale.Results: According to the de Boer scale, at a background luminance of 50cd/m(2), the discomfort glare for all studied vehicles was between 1.98 and 4.05 in high-beam mode and between 3.5 and 5.4 in low-beam mode. At a background luminance of 1cd/m(2), discomfort glare was between 0.41 and 2.48 in high-beam mode and between 1.93 and 3.84 in low-beam mode. In high-beam mode, the average levels of discomfort glare of these vehicles gradually increased when the distance between cars was reduced by up to about 20m. In low-beam mode, there was no discomfort glare up to a vehicle distance of 40m. In addition, at an angle of 1.15 degrees-5.73 degrees between the line of sight and light of vehicles in high-beam mode, the level of discomfort glare was increased, but at an angle of 5.73 degrees-22.9 degrees the level of discomfort glare was reduced. In low-beam mode at an angle of 2.86 degrees-22.9 degrees, the level of discomfort glare was almost identical. The results show that in high-beam mode and with a 100-m distance between vehicles as well as in low-beam mode at intervals of less than 40m between cars, discomfort glare is created.Conclusion: It can be concluded that by providing solutions such as installing road lighting system, an increase in luminance of roads, separating or widening road lanes, increasing the lateral distance between vehicles, and increasing the angle between lighted vehicles and drivers can noticeably reduce discomfort glare.