Safer Nighttime Driving

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Automatic-dimming headlights cut the glare
Most drivers don't use a standard nighttime safety feature-their high beams. Those who do often forget to lower them for oncoming traffic. There are two safety problems here. Failure to utilize high beams shortens the nighttime driver's vision of the road ahead.

Cars traveling 35 mph using low beams "out drive" their headlights and can't see far enough down the road to detect and react to potential hazards or pedestrians. The glare from high beams left on when passing an oncoming car or when approaching a car in the lane ahead, can temporarily blind that driver, slowing down their reflexes and increasing their braking distances.

Troxler Effect
PA study by Dr. Alan Lewis, who runs the College of Optometry at Ferris State University in Big Rapids, Michigan, found that during nighttime driving, headlight glare from the vehicles traveling behind you can be blinding. Even after the source of the glare is removed, an after-image remains on the eye's retina that creates a blind spot. Known as the Troxler Effect, this phenomenon increases driver reaction time by up to 1.4 seconds. That means that if driving at 60 mph, a motorist would travel 123 feet before reacting to a hazard. Normal reaction time to a change in driving conditions is .5 seconds and the distance traveled before applying the brakes is 41 feet when traveling at the same speed.

Approximately 42 percent of all crashes and 58 percent of fatal crashes in the United States occur at night or during other poor visibility conditions, according to statistics at the National Highway Traffic Safety Administration. These 2.8 million annual police-reported crashes, including 23,000 fatal crashes, represent incidents in which reduced visibility may have been a contributing factor.

Our eyes normally dilate at night to allow more light to enter the eye, making them much more susceptible to glare from high-beam headlights. As we age it takes our eyes longer to recover from the blinding effects of glare. We are an aging society with those 65 or older representing 12.3 percent of today's U.S. population and increasing to represent 20 percent of the population in 2030.

J.D. Power Study
J.D. Power recently completed a study of what drivers do to avoid glare from oncoming or following headlights. The results are scary. Most people, 83 percent, turn their rear view mirror up or down, so they escape the glare, although they then have no idea what is behind them. Another 58 percent admit to blocking their view with their hand or an object. And, scariest yet, 22 percent have worn sunglasses at night to avoid glare. These strategies put drivers at risk, but they are far more dangerous for pedestrians.

Pedestrians are four times more vulnerable at night than during the day. Over 2,500 pedestrian fatalities per year are attributable to darkness, according to the Department of Transportation. Low visibility is a greater contributing factor to pedestrian deaths than drunk driving.

Technology for Safety
Technology is coming to the rescue. SmartBeams produced by Gentex and debuting on the 2005 Cadillac STS and 2005 Jeep Grand Cherokee, automatically control the headlights through a camera mounted in the rear view mirror. When there is no traffic ahead, the high beams are turned on. When sensors detect oncoming headlights or the red lights of a vehicle in the lane ahead, SmartBeams begins to dim the headlights until they gradually revert to low beams as the other vehicles draw closer. As the vehicles draw away, the sensors gradually bring the headlights back to high beam.

SmartBeam's "camera on a chip" monitors surrounding traffic conditions in order to regulate the headlight intensity. The camera can tell the difference between headlights of oncoming cars and red taillights of forward vehicles and the light emitted by road signs, street lights, or building lights. It ignores those road side light sources and reacts only to light coming from other vehicles.

Because the system is installed in the rear view mirror where it is protected inside the vehicle cabin, the view is kept clear by wipers and defrosters and the mounting gives it a superior view of the road.


by Cathy Nikkel / autoMedia.com

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