SEARCH BLOG: AUTOMOBILES
From Science Daily; 2001
Study Shows High-Intensity-Discharge Headlights Improve Night VisibilityFrom the British Journal of Medicine; 2003:
ScienceDaily (July 2, 2001) — TROY, N.Y. - Researchers at the Lighting Research Center (LRC) at Rensselaer Polytechnic Institute report that HID (high-intensity-discharge) headlights enable drivers to see more effectively at night than conventional tungsten-halogen lights.
The LRC study has recently been featured in USA Today and on the NBC Nightly News.
Based on field experiments in which drivers responded to objects in their field of vision while using both sorts of lighting, LRC researchers concluded that drivers using HIDs were better at "detecting edge-of-roadway hazards, such as pedestrians and animals."
British Journal of Ophthalmology 2003;87:113-117Not much has changed since these studies were made. Many luxury cars including high-riding SUVs use these headlight systems. The question is whether or not they really help the driver of the vehicle with the HID system as much as they distract other drivers who are being tailgated by them or drastically reduce the vision of on-coming drivers. I suspect that most drivers really don't believe HIDs are appropriately placed or directed in SUVs and trucks.
© 2003 BMJ Publishing Group
Why HID headlights bother older drivers
M A Mainster, G T Timberlake
Department of Ophthalmology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160-7379, USA
Martin A Mainster, PhD, MD, Department of Ophthalmology, University of Kansas Medical Center, 3901 Rainbow Boulevard, Kansas City, KS 66160-7379, USA;
Driving requires effective coordination of visual, motor, and cognitive skills. Visual skills are pushed to their limit at night by decreased illumination and by disabling glare from oncoming headlights. High intensity discharge (HID) headlamps project light farther down roads, improving their owner’s driving safety by increasing the time available for reaction to potential problems. Glare is proportional to headlamp brightness, however, so increasing headlamp brightness also increases potential glare for oncoming drivers, particularly on curving two lane roads. This problem is worse for older drivers because of their increased intraocular light scattering, glare sensitivity, and photostress recovery time. An analysis of automobile headlights, intraocular stray light, glare, and night driving shows that brightness rather than blueness is the primary reason for the visual problems that HID headlights can cause for older drivers who confront them. The increased light projected by HID headlights is potentially valuable, but serious questions remain regarding how and where it should be projected.
My own feeling is that there should be a sensing system on the back of all vehicles that turn on the backup lights whenever too much light is directed at the sensors... whether from high beams or HIDs that are too close. That would be an effective signal to either back off or pass.
If you insist of trying to distract others with your misaimed, misaligned, misplaced, HID headlights, you should be informed that your efforts are working... with an appropriate message.As far as on-coming vehicles are concerned, old-fashioned high beams are a good signal, too. I use them on my F-250, as appropriate.