Evaluation of Discomfort Glare and Pavement Marking Material Visibility for Eleven Headlamp Configurations
This research effort focused on ascertaining the headlamp technology (of the eleven specified) that minimized the amount of discomfort glare and maximized the visibility of three types of pavement marking materials used in the study. Two baseline conditions, halogen low beam (HLB) and high-intensity discharge (HID) were measured both individually and in combination with three levels of UV-A. In addition, three other headlamp configurations were evaluated.
Discomfort glare was measured subjectively for each headlamp configuration. Pavement marking visibility was directly measured via pavement marking detection distances. Thirty participants representing three age groups participated in this study: young (18-25 years old), middle (40-50 years old), and older (60 years and older). The headlamp technology and the pavement marking material needed to be beneficial for all age groups as all would potentially use the new technology if it were implemented in vehicles and roadways in the future.
Participants evaluated discomfort glare at both a far and close distance using the nine-point DeBoer scale and evaluated pavement marking visibility by indicating when they could see the first and last pavement markings in each of the three sections.
Overall, it was found that the HID configurations (HID, Middle UV-A + HID, High UV-A + HID) with a sharp cut-off beam pattern provided the least amount of discomfort glare. In contrast, the halogen configurations (HLB, Hybrid UV-A + HLB, Middle UV-A + HLB, High UV-A + HLB) and high output halogen with a straight-ahead beam pattern provided the longest detection distances. Two of the pavement markings: a two part liquid system (developed by 3M) and a fluorescent paint provided longer detection distances than a thermoplastic marking.