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.