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Thursday, February 19, 2009
Night Driving Safety Tips for Night Vision, Driving Distractions and Drowsiness
Night time driving (between 6:00 PM and 6:00 AM) only accounts for 23% of all vehicle miles traveled yet it accounts for more than 50% of all fatalities for vehicle occupants age 16 and older.
The limitations and thus the dangers of driving at night may seem obvious but, with a death rate that high, reviewing some of the obvious and less obvious reasons for such a high fatality rate might be in order.
Night vision – During daylight, your eye's iris closes, allowing a very small opening to let in the bright light. This narrowly focuses the light entering the eye through the pupil to the center of the lens hitting a narrow spot of the retina at the back of the eye. At night, the iris opens wide to allow in more light and that has the effect of focusing the light on a much larger area of the lens preventing the light from focusing on that narrow point. This has the odd effect of slightly improving your peripheral (side) vision but makes it more difficult to focus on objects further out to the front.
The opening and closing of the iris becomes a problem when traveling from well lit streets to dark roads. When you pass from darkness through a brightly lit area and back to darkness again, it can take up to 30 minutes for your eyes to fully adapt and your night vision to be restored.
Over-driving headlights – On a dark country road it is impossible to see what is coming around the next curve or over the next hill. One of the most common causes of crashes on these types of roads is failing to negotiate a curve because the driver didn't see it coming and was driving too fast to keep the car on the road. Another common problem on these types of roads is animals, primarily deer, crossing the road. The combination of speed, average reaction time and the time it takes to bring a car to a full stop means that it is often too late, once you see an object on a dark road, to stop in time to avoid hitting it. On the dim setting, headlights only provide light out to a distance of 160 feet in front of the vehicle. In ideal conditions, a car traveling at 40 mph needs a total of 189 feet to come to a full stop; a difference of 29 feet. Adjusting your speed depending on light conditions, will ensure your car can stop within the distance seen in the headlights.
Seat belts – For some reason, seat belt use seems to decline among those who drive at night. Two thirds of the fatalities at night involved vehicle occupants who weren't wearing seat belts.
Driving drowsy – The hours between midnight and 3:00 AM see the highest fatality rate of the day. Drivers who are tired don’t react as fast and they don’t make good driving decisions. Drivers who are sleepy are a crash waiting to happen. If you are not normally awake during these hours, avoid driving.
Distractions – At the time of night when it is most critical to keep your eyes on the road, distractions that take your eyes off the road can be deadly. Dialing and talking on cell phones, eating, loading a CD all take your eyes off the road. At 40 mph, you will travel almost 180 feet in just three seconds. Studies show that almost 80 percent of crashes involve driver inattention within three seconds of the crash.