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Disorienting headlights© St. Petersburg Times published September 18, 2002 Those blazing bluish-white beams barreling down the highway toward you aren't from an oncoming UFO or a runaway train. But for some drivers, they can be just as disorienting and potentially dangerous. High-intensity-discharge (HID) lights are prominent on many new luxury cars and trucks. Instead of the traditional tungsten filament heated inside a halogen capsule, HIDs work by passing an electric current through xenon gas, with the resulting light projected by reflectors. They produce about three times the output, project a wider beam, use less power and last longer than tungsten-halogen lights. But their benefits are offset by the problems they create for other drivers. A recent study by the University of Michigan Transportation Research Institute found that HIDs have not fully met their promise to improve nighttime driving safety and may actually pose a greater nighttime hazard to many older drivers. In several situations, the university study found, conventional headlights are often safer than HID lights. While HID headlights emit more light than tungsten-halogen ones, the beams are mainly directed to the sides of the road. HID beams might be good for curves, but traditional headlights are better at illuminating the center of the road and straight ahead, which is more important for safety, the study confirmed. The study also found that conventional headlights are better than some HIDs at illuminating distant pedestrians and markings on the right side of the road and at illuminating distant, overhead signs and signs on the left shoulder at all distances. If you're a driver over 55, you could have another reason to worry about HIDs. Some vision researchers have found that it takes more than a second for the eyes of a older driver to snap back to normal after momentary headlight glare. Drivers can respond on the NHTSA Web site (www.nhtsa.dot.gov). The current headlight standards haven't had a major revision since beingestablished in 1968. While the glare from HIDs has yet to be blamed for any injuries or accidents, the NHTSA shouldn't be in the dark about drivers' concerns.
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From the Times Opinion page Editorial Editorial Letters Bill Maxwell |
