What is a Safe Following Distance?

Following too Closely is the Primary Cause of Rear-End Crashes

How dangerous is it to follow another vehicle too closely?

According to available crash statistics, it is the fifth leading cause of auto collisions.

For your DMV test, you should remember that following other vehicles too closely, or tailgating, is the primary cause of rear-end crashes.

You reduce the risk of rear-end crashes by always keeping a safe following distance between you and the vehicle in front of you.

What Does a Safe Following Distance Mean?

Keeping a safe following distance means you must give yourself enough time and distance to stop safely should the vehicle ahead of you stop short or suddenly hit something.

In the past, experts often suggested keeping one car length of safety distance for every ten mph, which meant keeping a distance of at least six car lengths when your speed was 60 mph.

The Two-Second Rule

Later, the “two-second rule” was introduced. The new recommendation suggests your car should pass a fixed object two seconds after the car ahead of you passes the same object.

Here’s how it works:

Choose a fixed point: When driving, select a fixed point on the road ahead, such as a road sign, tree, or overpass.
Count the Seconds: When the vehicle’s rear end ahead of you passes that fixed point, start counting seconds (“one thousand one, one thousand two”).
Check your distance: If you pass the same fixed point before you finish counting, you’re following too closely. Slow down and increase your distance, then try the count again.

The Three-Or-More-Second Rule

Nowadays, experts recommend the 3-second-or-more rule instead. Or even a four-second rule.

Some state driver manuals still recommend the two-second rule, but most have changed it to three- or four-second.

Why the Rules Matter

The rules help prevent rear-end collisions, which are common when drivers follow too closely and don’t have enough time to react if the car suddenly brakes.

It takes time to perceive a hazard, decide to brake, and then actuate the brakes. The three- or four-second rule provides enough buffer for this reaction time.

The rules work at all speeds. As speeds increase, the distance between vehicles also increases. Whether driving slowly in a residential area or at highway speeds, the distance covered in three or four seconds increases as your speed does.

So, What is a Safe Distance?

There is no exact answer to this question. Even if a three-second following distance may be safe in good conditions and when following another passenger car, it does not mean you can use the same distance in every situation.

Anytime your stopping distance is affected by bad road conditions, weather conditions, or simply the weight of your car, you must increase the distance.

Increasing the distance is also a good idea when following motorcycles with a shorter stopping distance or when large vehicles block your view.

You should also be careful when entering work zones, where rear-end crashes are more common because of sudden slow-downs or stops. Be attentive to the flow of traffic and adjust your distance accordingly.

What You Will See on the DMV Test

Expect questions about the following distances on the computerized knowledge test. Questions typically focus on the fact that you must increase the distance under certain conditions and less on the number of seconds.

Make sure you understand the difference between the words increase and decrease!

When to increase your following distance:

• Slippery road conditions, which include rain, fog, ice, snow, gravel, oil spill, etc.
• Low visibility; like fog, rain, smoke, or dust.
• Following motorcycles.
• Driving behind buses, large trucks, and other drivers who can’t see you.
• Following emergency vehicles with activated lights.
• A driver behind you wants to pass and may need the gap.
• Being followed too closely.
• Carrying a heavy load or pulling a trailer.
• Following vehicles that must stop at railroad crossings.
• In work zones or unfamiliar areas.

Remember, in real life, it is your job to be ready when the driver in front of you suddenly stops. It doesn’t matter if the road is slippery or if you are on the phone; you must be able to stop.

Your stopping distance is affected by how well you can see ahead, the time it takes to react, and the condition of brakes, tires, and pavement.

Be alert and always know what is happening around your vehicle.

Got this?

Results

-

Good job! You’ve got this.

Oops! How did that happen? Did you tap on an answer by mistake?

#1. Which is the main cause of rear end crashes?

Drivers following other vehicles too closely

A. Drivers following other vehicles too closely

Poor roadways and bad weather

B. Poor roadways and bad weather

Drivers driving too slowly

C. Drivers driving too slowly

Most rear end collisions are caused by the vehicle in back following too closely. If someone is tailgating you, move to another lane or turn off the road as soon as possible and allow the tailgating vehicle to pass.

#2. Which is always a safe folowing distance?

Two seconds

A. Two seconds

Four seconds

B. Four seconds

None of the above

C. None of the above

No following distance is safe under all conditions. Try to keep a 3- or 4-second following distance under ideal conditions. During poor road and weather conditions or when following motorcycles and trucks, increase your following distance even more.

#3. A rule of thumb is to leave a three-second or four-second gap between your vehicle and the one in front when conditions are:

Foggy

A. Foggy

Ideal

B. Ideal

Icy

C. Icy

This rule of thumb is for ideal conditions. With bad road conditions or poor visibility, you should allow more than four seconds.

See your result

DMV Questions and Answers by State