Visual Benefits of High-Intensity Discharge Automotive Forward Lighting

Recent studies have shown that high-intensity discharge (HID) headlamps provide visual benefits to the vehicle operator that may lead to greater nighttime driving safety.[1] This paper is an extension of that work to further examine the role of beam pattern. An experimental field investigation is described that explores the visual performance aspects of HID forward lighting systems meeting North American beam pattern standards.

This study further explores and quantifies the overall benefits of HID systems by direct comparison to conventional halogen systems. It examines and compares two systems producing typical Society of Automotive Engineers (SAE) J1383 beam patterns. Subjects perform a visual tracking task, cognitively similar to driving, while seated in the driver's seat of a test vehicle. Simultaneously, small targets located at various angles in the periphery are activated, with subjects releasing a switch upon detection so that reaction times can be measured. Reaction times greater than 1 second are considered misses.

From the results, comparisons are made among the HID and halogen systems in terms of reaction time to signals at different peripheral angles, and in terms of missed signals. Potential implications of the results on driving safety and on the development or refinement of HID forward lighting systems are also discussed.