What Does “Safe Following Distance” Mean on the Highway?

When drivers follow the vehicle in front of them too closely, it’s called tailgating. Tailgating is actually a leading cause for rear-end accidents across Richmond. It not only causes the driver in front of you to feel more stressed, but it can also cause you to slam into their vehicle by making one simple error, leading to a car accident.

Following at a safe distance can reduce your risk of a car accident. But what does that mean? How close is “too close,” and how far should you be from other cars?

What is considered a safe following distance?

According to Virginia § 46.2-816, “the driver of a motor vehicle shall not follow another vehicle, trailer, or semitrailer more closely than is reasonable and prudent, having due regard to the speed of both vehicles and the traffic on, and conditions of, the highway at the time.”

It can be difficult knowing what “reasonable and prudent” means exactly. This is when you can use the “three-second rule.” Drivers should leave at least three seconds of space between their vehicle and the vehicle in front of them.

To calculate these three seconds, you wait for the vehicle in front of you  to pass a certain object, such as a tree, pole, sign, or highway mile marker. Then, you say out loud or in your head, “1-1,000, 2-1,000, 3-1,000” before you pass that same exact object. If you pass the object before you say “3-1000,” you’re following too close to the driver ahead of you, and should slow down.

Why use the three-second rule to determine a safe following distance?

People have a hard time accurately assessing speed, space, and size while in a moving vehicle. Analysis of data for perceived speed while driving, published in PLOS One in 2023, found the following:

[D]rivers frequently overestimate or underestimate their speed. For example, after exiting a highway and entering an urban road, drivers typically underestimate how fast they are traveling. Tunnel sidewall markings, on the other hand, often lead to drivers overestimating driving speed.

Previous studies have revealed several visual and environmental factors that critically influence speed perception. The overall and central fields of view, for instance, play an important role in speed perception, with decreases in the central field of view leading to speed being underestimated. In-vehicle factors also affect the driver’s perception of their own speed; for example, vehicle noise reduces the variability of correct speed perception, whereas distraction induced by secondary tasks and the absence of a speedometer both lead to speed underestimation. Additionally, speed perception is influenced by external environmental factors, such as curves in the road. Research suggests that drivers often underestimate their speed on curves in both actual and simulated driving scenarios.

We also cannot accurately assess size or space. According to a small study at Ohio State University, the average person thinks the white lines on a highway are about two feet long (they’re actually 10 feet long), and that they are painted in two-foot intervals (it’s actually 30 feet), so most drivers think they have only traveled a few feet between white lines, when in fact, they have traveled 40 feet: the 10 feet of the white line, plus the 30 feet between them.

This is why the three-second rule works: it does not matter how fast we think we are going, or how much space we think there is. The counting is consistent, and it gives us the information we need no matter how our brains perceive it.

Furthermore, science has found that three seconds is the minimum we really need to react to anything. Says Travelers.com:

Think of following distance in terms of time, not space. With a standard of 2.5 seconds, highway engineers use time, rather than distance, to represent how long it takes a driver to perceive and react to hazards. The National Safety Council also uses this standard (plus a little extra for safety) when recommending the three-second rule for following distance.

Should I always follow the three-second rule?

While several safety organizations recommend the three-second rule, such as the National Safety Council, there is some maneuverability. The Virginia Department of Motor Vehicles (DMV) states that you can have a following distance of two seconds if the speed limit is less than 35 mph, three seconds if the speed limit is between 35 to 45 mph, and four seconds if the speed limit is between 46 to 70 mph. Therefore, it is up to you to determine what the speed limit is in the area you are driving in and make sure that you are keeping at least two, three, or four seconds of following space between you and the vehicle ahead.

In addition, if there are bad or inclement weather conditions, you should increase your following distance. For example, if it is snowing or raining, you should extend the three-second rule because these weather conditions can cause you to quickly slide or hydroplane into the vehicle in front of you. Another factor to consider is if you are towing or transporting a trailer, camper, boat, or anything else on the back of your vehicle. While doing this, you should add an additional second per every additional 10 feet added behind you. The reason that this is suggested is because when you are carrying or towing large items on the back of your vehicle, their weight can make it a lot more challenging to stop or slow down.

You may also want to give more room for yourself to stop if you are following a motorcycle. These small, two-wheeled vehicles already do not offer riders much protection in the event of a crash. Since they are known to stop very quickly and suddenly, you should try to provide extra space to ensure that you do not slam into the back of a bike and cause the rider to be ejected or thrown off, which could lead to fatalities.

How many car lengths is a safe distance?

If you want to calculate a safe following distance by using car lengths, the recommendation is one car length per every 10 mph between you and the vehicle in front of you. This means that if you are driving on a highway that has a speed limit of 50 mph, you will need to make sure that about five cars can fit in between you and the vehicle ahead. The faster you drive, the more space that is needed to make sure that you can stop or slow down in time. Given how poorly we perceive space and size, however, you are probably safer if you count seconds, not cars.

At Phelan Petty Injury Lawyers, we take car accident cases seriously. Our Richmond-based car accident attorneys listen to your experience, review your legal options, help you file a claim, and collect valuable information and evidence. Our team is known to never back down without a fight, and we will do everything we can to help you achieve the maximum compensation possible to help you rebuild your life again after the accident. All you have to do is call our office or submit our contact form to schedule your free and confidential case evaluation at our Richmond office today. We proudly serve clients throughout Virginia.

Related:

• Can You Turn Right on Red in Virginia?
• What Does “Safe Following Distance” Mean on the Highway?
• Is Passing on the Right Illegal in Virginia?