Night Driving

Some police officers spend their entire duty shift driving in darkness, and yet many are unaware of the special hazards night driving presents, or don't know effective ways to deal with them.

The major difference between day and night driving is the accident rate. When you consider that 90% of a driver's reaction depends on vision, and vision is severely limited at night, it is no surprise that the night driving accident rate is roughly three times that of daylight driving. The cause of the decreased vision varies. At night, the driver's normally wide field of vision is narrowed to the field of view illuminated by your headlights, the headlights of other vehicles and fixed road lights. Depth perception, color recognition, and peripheral vision are compromised after sundown. Older drivers have even greater difficulties seeing at night. A 50-year-old driver may need twice as much light to see as well as a 30-year-old.

Adding to the problem, most drivers do not slow down significantly when driving at night, despite their reduced visibility. The reduced visibility can cause even the most cautious driver to overdrive their headlights.

A scenario is in order here:

Its night and you're driving with your low-beam headlights on, which permit you to see about 150 ft. ahead of you. If your speed is 40 MPH (approximately 60 ft/sec.), you have 2.5 seconds' worth of vision ahead of you. If there was an emergency waiting for you just beyond your range of vision, you would have 2.5 seconds of reaction time. At 60 MPH you would have approximately 1.7 seconds of vision and reaction time. Having 2.5 seconds to react should be sufficient--exciting, but sufficient. When it gets down to 1.7 seconds it will be all a matter of luck, and all this is assuming that your headlights are clean and working at maximum efficiency.

For your EVOC program, it is a good idea to measure how much illumination your vehicles supply. Place a vehicle in an area that supplies no ancillary light, and measure the distance (high and low beam) illuminated.

One of the most dangerous aspects of night driving is one that we can do little to control: blinding glare from oncoming headlights. An immense amount of research has been conducted into the problems of glare and night vision, and all these studies have reached the same startling conclusion: When your eyes are hit by a bright beam of light from an oncoming car, you can't see.

How much is vision impaired by this type of attack? We can be completely blinded for one or two full seconds. This means that at just 40 mph, you will drive 120 feet without being able to see anything clearly.

Drivers can be affected by the oncoming glare of headlights as far as 3,000 feet away. If you feel you won't be able to see after a car approaching you has passed, slow down and try not to look directly at those headlights. Looking at the right side of the road is often effective.

People need to see you, too

Bright color and high contrast make objects visible at night. That's why it's a good idea to have some reflecting tape somewhere on your car, especially if the car is a dark color.

Good night visibility is more than just having a set of lights mounted on your vehicle. Equally important is the alignment of those lights. You can have the best headlight system in the world, but if those lights point off in crazy directions, they're not going to do much good, except to make your car a kind of traveling light show. Tests can be performed to see if the lights on your department's cruisers are aligned properly.

It's important as well to keep headlights clean. As much as half of a headlight's total output can be absorbed by dirt on the light's surface. Keeping headlights clean is especially important in winter, when they're frequently covered with road dirt and encrusted with salt.

Likewise, a clean windshield is vital for driving, whether in day or night. Streaks and smears on windshields can produce extremely disorienting kaleidoscopic effects when lights shine on them at night. Make sure your windshield washers work, that your windshield wiper blades are clean and not old and worn out, and that the windshield wiper fluid container is kept filled.

Headlights cannot see around corners. They light only the path of travel that is dead ahead. When we do turn corners at night, we tend to follow the headlights around that corner. When you turn your car, scan the areas to the side and beyond the headlights. When backing up, only your backup lights are available and on most makes of cars, they aren't much. There's not much more you can do but cope with this reality.

Here are some rules to help minimize the hazards of night driving:

  1. Adjust your speed to the range of your headlights. High beam headlights in good working order illuminate the road for about 300 ft. ahead; low beams for a much shorter distance.
  2. Keep your eyes moving. Don't fall for the temptation of focusing on the middle of the lighted area in front of you. Search the edges of the lighted area. Look for other patches of light that could be cars. Look for them at hilltops, on curves, or at intersections. Where there are many distracting neon signs or brightly lighted buildings, try to concentrate on street level activities.
  3. Protect your eyes from glare. Prolonged exposure to glare from sunlight during the day or headlights at night can temporarily ruin your night vision, while also leading to eyestrain and drowsiness. Wear good sunglasses on bright days and take them off as soon as the sun goes down.
  4. Keep windshields and headlight lenses clean.
  5. Use your lights wisely. Use high beams when possible. Switch to low beams when following another car or encountering oncoming cars. Flash your lights as a signal when overtaking and passing.

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