One of the biggest benefits of autonomous vehicle systems is that they tend to do what they’re programmed to do. In contrast, you can teach a human driver how to calculate and maintain a proper following distance — but that person may or may not follow the instruction given.
The computer, however, will behave as it is programmed. It will consistently calculate following distance and take appropriate action when your truck is too close to the vehicle ahead. The computer won’t become complacent, get mad at its dispatcher or be distracted by a text message.
That’s NOT to say that automated vehicles (AV) and advanced driver-assistance systems (ADAS) are a cure-all for issues faced on the highway, especially in the trucking industry. Detractors will correctly point out that it’s impossible to program for every possible circumstance a driver might face in a given day. In some cases, there is simply no substitute for a human being’s ability to reason and to use good, old-fashioned common sense.
The problem is, there isn’t much reasoning or common sense displayed by a tailgating trucker.
Why do some drivers get too close?
Drivers follow too closely for a number of reasons — and most of them aren’t even remotely related to common sense.
Often, tailgating truck drivers are frustrated that the vehicle ahead isn’t going fast enough, and they hope to intimidate that driver into moving out of the way.
At other times, drivers make misguided attempts to rationalize the situation: “If I allow a bigger gap, some four-wheeler will just jump in there” is a common — if less-than-intelligent — excuse for tailgating. Some drivers foolishly believe that staying close enough to the vehicle ahead to prevent another vehicle from getting into that space somehow gets them to their destination sooner.
In reality, following too closely can easily cause a crash — and being involved in an accident is of the best ways to guarantee that your delivery will be late. At that point, the late delivery may be the least of the consequences you’ve got to worry about.
A tailgating citation can make it hard to find a job.
Following too closely is considered a “serious violation” by the Federal Motor Carrier Safety Administration (FMSCA). It’s ranked right up there with excessive speeding, unsafe lane changes and reckless driving. Two serious violations can result in a suspension of a driver’s CDL.
Even without a conviction and the accompanying fine, a “following too closely” violation can still appear on a driver’s Pre-Employment Screening Program (PSP) report. A PSP report showing an accident PLUS a following-too-closely violation can result in a motor carrier deciding not to offer you a driving job. After all, a rear-end collision caused by a tailgating semi truck is enough to make any personal injury attorney drool in anticipation.
Learn to calculate safe following distance — and abide by it.
For the sake of their career and livelihood (as well as professional pride), every driver needs to know how to calculate following distance. On top of that, you’ve got to make a personal commitment to maintain that distance in every situation.
Several methods are taught in various defensive driving programs, but methods like counting “truck lengths” or estimating distances in feet or meters are unreliable at best. Drivers have to calculate distances while allowing for their speed and the speed of the vehicle ahead AND taking other factors into account, such as the condition of the road surface, the weight of the cargo, condition of tires and brakes, and more.
The most accurate way to calculate following distance is by time interval.
It’s a method that works regardless of speed: Count the seconds between when the vehicle ahead of you passes a specific point until your vehicle reaches the same point. You’ll need to decide the number of seconds to allow in advance, and the figure may vary depending on circumstances.
For example, five seconds might allow enough space for you to safely stop in most instances. You might choose to add an additional second if the road surface is wet, and maybe a couple of extra seconds if your trailer is heavily loaded.
The point is that more seconds equal more time to stop.
How much time should be allowed to ensure a safe stopping distance is a question that sparks debate. In reality, six seconds is probably adequate for most situations — but there’s no penalty for making it seven seconds instead. You’ll never regret having too MUCH time to brake and avoid an accident.
While deciding, think of your speed in terms of feet per second (fps) rather than miles per hour (mph). Here’s the simplest way I know to determine your fps: Multiply your speed in mph by 1.5 to get fps (it’s actually 1.4666667, but you don’t want to get distracted by the math). So, 50 mph = 75 fps, 70 mph = 105 fps, and so on.
At 65 mph, you’ll cover more than 95 feet per second. It’ll take at least 655 feet to stop an 80,000-pound tractor trailer. You’ll cover that distance in less than 7 seconds when you aren’t braking.
In most cases, the vehicle in front will also need some distance to stop, and that could provide you with some extra stopping distance. If that vehicle hits something, however, it could stop much sooner, triggering a rear-end collision.
Consider the different factors that make up stopping time.
First, you’ll need to perceive that a hazard exists that requires you to stop. That takes a half-second or so. You’ll need to react by physically moving your foot to the brake pedal; that’s another half-second.
If you’re tired, bored, distracted, ill or impacted by other conditions, your perception and reaction times will increase even more.
Air-brake equipped trucks are subject to “brake lag” — the time it takes for service air lines to pressurize and physically move brake pads or shoes into contact with drums or rotors. The first 1.5 seconds of “braking” don’t reduce your speed at all, and you’ve already covered nearly 150 feet without slowing down a single mph.
Once the brake shoes or pads engage, you’ll finally begin slowing. If conditions are perfect, your vehicle should stop within the previously mentioned 655 feet
Unfortunately, conditions are often imperfect. Wet roads, worn tires, out-of-adjustment brakes and other factors could add stopping distance.
In the end, it all comes down to you.
You can’t control the actions of others — but you CAN control how you react. Professional drivers know the area in front of the truck is your best defense against collision with another vehicle.
Before looking for an “out,” being able to stop safely is your primary defense.
By understanding proper following distance — and by programming yourself to maintain that distance regardless of the circumstances of the day — you can reduce your risk of a collision and increase your chances of getting home safely.
Cliff Abbott is an experienced commercial vehicle driver and owner-operator who still holds a CDL in his home state of Alabama. In nearly 40 years in trucking, he’s been an instructor and trainer and has managed safety and recruiting operations for several carriers. Having never lost his love of the road, Cliff has written a book and hundreds of songs and has been writing for The Trucker for more than a decade.
