How Your Car Keeps You on the Road

Technology in the automotive realm has developed so quickly that it’s easy to forget that there was a time in the not-so-distant past when radios, airbags, and power windows were optional.

There’s one area, however, that has developed more quickly than others—safety mechanisms. The most recent cars can tell you if someone is in your blindspot, have camera systems that you could shoot a movie with, and even (sort of) drive themselves! But in this article, we’re getting back to basics and going over three fundamental safety features that every modern car has: traction control, stability control, and anti-lock brakes.

Fortunately for us, these features are now standard on most modern cars, and have been for some time. But if I were a betting man, I’d wager that most people don’t even know they exist. Nevertheless, it’s both important and interesting (if you’re a nerd like me) to understand how these systems, which can be categorized as driver’s aids, work to keep you out of that roadside ditch.

The first thing that can’t be ignored when discussing these systems is the nomenclature that is used to describe them. The anti-lock braking system, or ABS, is rather simple, because it can’t be turned off and is a system that the driver, as far as control over it goes, is completely isolated from. It’s a passive system; it intercedes when it’s needed, automatically.

Traction and stability control, however, are systems that the driver can interact with and even disable in most modern cars, so naturally each automaker had to come up with a confusing and unique acronym to refer to their stability or traction control system, for marketing purposes. Whether it be DSC, ESC, TC, PDCC or any other alphabet soup, all you need to know is that they all do pretty much the same thing.

Traction and stability control help you keep control of your car.

Alright, let’s start with the simplest, but arguably the most important: ABS. ABS is a system that you hopefully don’t reap the benefits of often, because if you’re using it, chances are you’re making an emergency stop, putting the brake pedal all the way to the floorboard.

If you were to do this without ABS, your brakes would lock up, and so would the wheels, bringing you to a dramatic halt with smoking tires, and probably not in a straight line. When your brakes lock up, the tires are of course no longer rolling, which exponentially limits your ability to control the car, and also lengthens stopping distance, as a static tire with little grip is not very effective at slowing the car down.

With ABS however, when you engage the brakes completely, the car will automatically release them for a fraction of a second just prior to the brakes locking up, and then re-engage them—so the tire, for the most part, keeps rolling and thus maintains grip while you’re slowing down. This prevents wheel lockup, and thus shortens stopping distances dramatically and allows the driver to maintain control during the stop. You can even hear ABS working sometimes during a hard stop. I don’t encourage you try this yourself, so head over to YouTube, and listen as the tires chirp intermittently as the car brakes. This is a byproduct of ABS releasing and re-engaging the brakes very quickly.

ABS may be the most impactful automotive safety feature of the 21st century.

Stability and Traction control, in contrast to ABS, are a bit more complicated. These systems are responsible for keeping you going in your intended direction when you get a bit overzealous with your cornering speeds, when you jab the throttle too hard, or when the roads are wet or snowy.

For organization’s sake, it would be ideal to discuss these two in separate paragraphs, but as you’ll quickly learn, they are too intimately related to do that. To put it simply: traction and stability control are put in place to prevent wheelspin, which is—unless you’re competing in formula drift—the enemy of control.

So how do they do it? Most modern traction and stability control systems are brake based, in addition to throttle controlling, so when wheelspin is detected (by sensors that monitor that) the car can apply the brakes to or cut power from a tractionless wheel, or wheels, to prevent them from spinning. In some cases, they send that power to a different wheel, allowing you to regain control.

This is where we reach a very important distinction that must be made between the two: traction control maintains control in a straight line, while stability control maintains control while cornering.

This delineation can sometimes be muddied by the systems working together in certain situations, but by and large, that’s how it works.

Take the Corvette, for example—it’s a high horsepower, rear wheel drive car. (Bear in mind that this example is an extreme one, for demonstration purposes. On more civilized “normal cars” the effects will be the same, but less pronounced.)

So you’re sitting in your Corvette at a complete stop, and you stab the gas pedal all the way to the floor. The car bogs a little bit, spins the tires for a second, and you’re off in a straight line. That was with traction control ​on. ​

Now let’s turn it off. You stab the throttle, you don’t move, and your rear tires erupt in a cloud of smoke. (Then your neighbors yell at you for doing burnouts in a residential area, again!)

In the first scenario, traction control kicked in as soon as you put your foot down, cutting the power supply to the wheels, despite your foot staying down, in order prevent them from spinning. This allowed you to accelerate.

In the latter scenario, no such thing happened, which allowed the wheels to spin freely. These same concepts apply to all cars, and a similar thing happens with stability control. When cornering, if the road is wet or if you get too heavy with your right foot, the car will want to spin out.

However, stability control can step in here to help you regain traction by applying the brakes to certain wheels, and cutting power, preventing the slide and keeping you going in the right direction, safely. Without stability control, the car would’ve kept going in that direction, and you would’ve spun out or entered into a spectacular slide, which you would then have to figure out how to control.

So the systems are very similar in that both control the amount of traction that the tires have, but ​for the most part​ stability control is working while cornering, while traction control is at work in straight lines.

Now to finish up, let’s talk about that “​for the most part.” These systems do sometimes work in tandem. If, for example, you are exiting a corner, and apply the gas too early, traction control will kick in to cut power and help you go straight while you exit the corner, and stability control will kick in and apply the brakes very briefly and only to certain wheels, for the same purpose.

So from Priuses to Porsches, these three systems are of the utmost importance in the automotive safety world. So much so that in 2012, the U.S. Government mandated that all new cars must be equipped with stability control.

To further corroborate the importance of these systems, research by the Insurance Institute for Highway Safety found that if stability control had been around since the invention of the automobile, nearly one third of all fatal car crashes could have been avoided. ​

That’s ​how important this stuff is, so be grateful it’s not 1960 anymore, and give your car a pat on the dash for doing such a great job at keeping you safe!

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