ANSI - American National Standards Institute
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Transportation Agency Investigates Headlight Glare Issues for Drivers


New York, Aug 13, 2003

Drivers have been calling the government about sightings of blinding blue lights on darkened streets and highways as of late. It isn’t science fiction or alien encounters; a new breed of automotive headlamps are inspiring angry reactions, a spate in theft, and a concentrated research effort by the National Highway Transportation and Safety Administration (NHTSA).

High Intensity Discharge (HID) lamps are a new trend in headlight fixtures on many new car models that are touted by some as being brighter, more supportive to aging eyes on dark roads, and looking stylish with their azure tint. Others argue that the powerful lights are simply too bright and create a dangerous glare for oncoming drivers. The lamps are also very costly – replacement can run over $1500 – and in New York City alone, there have been more than 800 reported headlight thefts this year, according to the NYPD's auto-crime division.

HID lamps have come to be known as xenon lamps, though it is not the xenon that contributes to the bluish tint. Xenon is added to the gas sealed inside the lamps and acts as a starter to quicken the rate at which they warm up for use. Xenon is responsible for the bright flash as the headlights are turned on, and glows brightly temporarily until the harder-to-ignite gases are fully alight. Mirrors inside the light assembly capture, amplify and direct the light; lenses aim and focus it.

All xenon lights sold in the U.S. must comply with Federal Motor Vehicle Safety Standard (FMVSS) No. 108, which specifies requirements for original and replacement lamps, reflective devices, and associated equipment. The purpose of this standard is to reduce traffic accidents by providing adequate illumination of the roadway, and enhancing the conspicuity of motor vehicles on public roads in daylight, darkness or other conditions of reduced visibility. The standard details all the photometric and physical requirements of all exterior automobile lamps in the U.S., including all aspects such as color, light intensity, stress tolerances, and heat tolerances for all vehicle exterior lighting equipment. Several standards from the Society of Automotive Engineers (SAE) also affect the design of automobile lighting systems, including SAE J 1647, Plastic Materials and Coatings for Use in or on Optical Parts such as lenses and Reflectors of High-Intensity Discharge Forward lighting devices used in Motor Vehicles and SAE J2009, Discharge Forward Lighting Systems.

Earlier this year, the National Highway Transportation Safety Administration issued a request for public comments to find out why drivers have been complaining about headlamp glare, particularly regarding the powerful HID lamps. The agency received more than 4900 responses, ranging from experiences with auxiliary lamps, low beam lamps and the HID lamps. On July 31, 2003, the NHTSA held a public meeting as part of its Research and Development Programs, and addressed glare complaints and problems, differences between HID and halogen headlamps, preliminary research findings, and future lighting research directions.

In addressing what rulemaking options might reduce glare problems, the NHTSA identified possible solutions that include new photometric specifications, reduced mounting height, and improved aim. Future NHTSA research on headlight glare will focus on topics that include comparing beam intensity distributions of HID lamps compare to halogen lamps, seeing distances and glare of HID and halogen lamps under different conditions, and whether drivers take longer or more frequent glances at bluish headlamps.

For more information on headlight glare and NHTSA research, view the presentation, " Forward Lighting: Problems, Research, Countermeasures," from the public meeting.

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