How to Avoid Collisions

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The rear end crash is one of the major crash problems. Traffic experts are convinced that rear end crashes can be prevented if drivers will observe a few simple precautions when following other vehicles.


A driver of a motor vehicle may not follow another vehicle more closely than is reasonable and prudent, having due regard for speed, traffic, and conditions of the roadway. You also have a duty to yield to following vehicles. AS 28.35.140 requires drivers on a two lane roadway outside of an urban area to safely pull over when there are five or more vehicles immediately behind.


  1. FOUR-SECOND RULE: The easiest way to calculate a safe following distance is by the four-second interval method. Watch the back of the vehicle ahead of you pass some definite point. Then count — “one thousand and one, one thousand and two, one thou- sand and three, one thousand and four.” That’s four seconds. If you pass the same point before you are finished counting, you are following too closely. When towing a trailer or the road surface is wet or slippery, increase the four seconds to six or more. You also can use the “Four Second Rule” at night to make sure you are not “over-driving your headlights.”
  2. Watch for brake lights. Shift your foot to the brake pedal promptly so you are ready to stop if necessary.
  3. Watch for shrinking distance between your car and the one ahead. This warns of impending crash with the vehicle ahead.
  4. Watch for stopped and standing vehicles ahead. Some drivers find it difficult to determine whether a distant car is in motion or stopped. Learn to relate vehicles to fixed objects.
  5. Look for problems that might develop for the driver ahead of you. This makes it easy to react in time.


Just as important as avoiding a crash with the vehicle ahead is to avoid being hit by the vehicle behind. To lessen the likelihood of a rear-end crash, a driver who is stopped or in the act of stopping can do a great deal.

  1. Be sure brake lights are clean and working properly. Flash brake lights when preparing to stop.
  2. Know what is going on behind you. Have an outside rear vision mirror and keep rear window clean and clear of frost and snow.
  3. Signal well in advance for lane changes, stops, or turns. The person behind you can’t read your mind.
  4. Slow down gradually over a long distance to give the drivers behind more time and space in which to react.
  5. Keep pace with the traffic within limitations of weather conditions and speed limits.


It is a well-known fact that the faster you drive the greater the impact or striking power of your vehicle. A fact not generally understood is how much greater the striking power of a vehicle is when you double the speed from 20 to 40 miles per hour. It is commonly believed that the striking power of a vehicle would likewise be doubled. This is not true. The impact is 4 times greater at 40 mph than at 20 mph. The braking distance is also 4 times longer. Triple the speed from 20 to 60 mph and the impact and braking distance are 9 times greater. Increase the speed to 80 mph and the impact and braking distance are 16 times greater than at 20 miles per hour.

Respect the potential destructive power of your vehicle when you increase speed. Speed properly related to traffic, road, and weather conditions, and skillfully controlled by a thoughtful driver need not be hazardous. In the hands of a thoughtless, uninformed driver it is deadly.