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Home > Chapter Programs > Driving Schools > Documentation > Highway Safety

Welcome to the Highway Safety School

This unique drivers' school is designed to introduce you to the fundamentals of car control and driving mechanics in a safe environment. We've constructed a series of driving exercises that are designed to provoke certain behaviors from your car. Each exercise illustrates a particular characteristic response of your car to road conditions and driver input. You'll learn proper and improper driver inputs for particular situations. By the end of the day, you'll understand how your car behaves under braking and cornering, and consequently you'll be a much better driver.
You will be scheduled for track, classroom, and skidpad sessions. Classroom sessions will cover the underlying principles behind each of the on-track exercises: what your car's tires are doing while you're negotiating the exercise, how your steering and acceleration inputs affect your car's behavior, and why some of your inputs work and some don't. Skidpad sessions will allow you to experience and practice recoveries from loss-of-adhesion situations in a safe, controlled, low-speed setting. You'll also learn why your instincts in such situations are almost always wrong.

This publication describes the purpose of the on-track exercises we'll be doing; refer to the track map on the last page for the exercise locations. In the morning, we'll do the exercises while driving counterclockwise, so that the turns will come up in ascending numerical order. In the afternoon, we'll run in the opposite direction. Each on-track exercise will involve guiding your car through a series of "mini-cones," or pylons.

Don't worry about hitting the pylons we use to mark the exercises. They're only six inches high and made of soft plastic, so they won't hurt your car. What may hurt your car is if you lose control while trying to avoid hitting a pylon. Always maintain control of your car, even if it means running over every pylon on the track!

Driving Theory

Before we begin, let's take a few moments to understand what actually happens when driving. Most of us don't think about driving; it's enough that when we point our car in a certain direction and step on the accelerator, the car goes where it's pointed. As long as nothing goes wrong, that's sufficient. However, our lack of knowledge hurts us in emergency situations.

You've probably lost control of your car at some point in time. Perhaps it was raining or snowing; you entered a curve a little too fast, turned the wheel, but your car kept going straight ahead. Or maybe you had to jam on your brakes suddenly and hope that you'd stop before hitting the car in front of you. In any case, you know that helpless feeling of being "along for the ride" with no control over what's happening.

What went wrong, of course, was that you asked your car to do something it couldn't do, either negotiate a curve at too high a speed or come to a stop in too short a distance. Physical laws govern the behavior of your car, and understanding those laws is the key to controlling your car. At the school, we'll show you--and let you experience--the physical limits of your car's ability to turn or stop. Most importantly, by experiencing and understanding these limits, you'll know what options you have in an emergency.

Fundamentally, driving is all about friction: specifically, the friction between your tires and the pavement. When you depress the accelerator, or apply the brakes, or turn the steering wheel, your tires generate frictional forces which are applied to your car to accelerate, decelerate, or change directions. Each specific demand you make on your car (e.g., turning a corner) requires a certain amount of force. Your car requires the least amount of friction with the pavement when traveling in a straight line at a constant speed. Accelerating, braking, or turning require more friction, with larger speed or direction changes (e.g., braking harder or turning sharper) requiring proportionally larger amounts of friction. If your tires cannot generate sufficient frictional force, your car will not do what you want.

Threshold Braking

When you apply your brakes, the frictional forces generated by your tires act to slow your car down. The harder you press on the brake pedal, the larger the generated force is, and the faster you slow down--to a point. If you press too hard, your tires will be unable to generate the force being demanded of them, and they will lock (i.e., stop turning and begin sliding along the pavement). This sliding still generates some friction, but it is important to note that it is less than the amount that was being generated just before they locked.

Therefore, the quickest way to slow your car is to depress the brake pedal with as much pressure as is possible without locking your tires. This technique is called threshold braking. It is difficult to modulate precisely the amount of pressure you apply to the brake pedal, and it's even tougher if you're trying to turn the car at the same time. However, if you brake with the ball of your foot, you'll have a lot more control.

Because untrained drivers have difficulty braking with maximum effectiveness, antilock braking systems (ABS) were invented. If you apply too much brake pedal pressure, the ABS will modulate the pressure for you; you can feel this as a pulsation in the pedal and hear it as a chattering noise.

If your car is equipped with ABS, you can always just mash down on the brake pedal, steer, and let the ABS do all of the work for you. However, true threshold braking, i.e., applying maximal braking just before the ABS kicks in, will result in slightly shorter braking distances. Therefore, you should learn and practice threshold braking by modulating the pedal pressure to keep the ABS from activating. We've designed three exercises that involve threshold braking to help you develop this important technique.

Handling

Two important aspects of your car's handling are balance and weight transfer. Balance is how your car's weight is distributed from front to rear and from side to side. The weight of your car generates proportional frictional forces (i.e., grip) at each tire, and these forces change profoundly when you accelerate, decelerate, or change direction; this is called weight transfer.

When you accelerate, weight transfers to the rear of your car, decreasing the grip available to your front tires and increasing the grip available to your rear tires. When you decelerate, weight transfers to the front of your car, enhancing front tire grip and decreasing rear tire grip. In a turn, weight transfers to the outer tires, reducing the grip of your inner tires. The amount by which grip changes at each tire in response to weight transfer is determined primarily by your car's suspension and its reactions to your inputs.

For a given corner taken at a given speed, each of your tires requires a certain amount of grip to maintain adhesion with the pavement. Higher speeds and tighter corners require correspondingly more grip. If weight transfer causes the grip available at a given tire to decrease below that which is required, it will lose adhesion and begin to slide against the pavement. If the sliding tire is at the front of your car, your car will understeer; if it is at the rear, your car will oversteer.

Understeer, or "push," occurs when your front tires lose adhesion with the pavement. Instead of following your intended path around the turn, your car will begin to run wide, as though you were steering less than you needed to. Understeer is often caused by entering a turn too fast or by turning the steering wheel too quickly: both upset the balance of your car.

The important thing to realize is that understeer occurs because your front tires are overloaded; they require more grip to maintain adhesion than is available. Steering more, i.e., trying to turn a tighter arc, simply overloads them more, making the understeer worse. To correct understeer, you must restore adhesion to the front tires by slowing your car and/or straightening the steering wheel; both reduce the grip required. Straightening the wheel is counterintuitive, because you're deliberately steering toward the outside edge of the pavement, but you must regain front-end adhesion before you can change your car's direction.

Oversteer, or "looseness," occurs when your rear tires lose adhesion with the pavement. Instead of following your intended path around the turn, your car will begin to rotate around your front tires, as though you were steering more than you needed to. To stop the rotation of your car, you must apply a countering force by steering toward the outside of the turn. You must also maintain your speed or accelerate slightly. This too is counterintuitive, because the last thing you'll think you need at that point is more speed. However, when you accelerate, you transfer weight back onto your rear tires, giving them more grip. It's important to recognize here that you're applying acceleration not to increase your speed, but to restore your car's balance.

Oversteer is often caused by sudden deceleration in a turn, either by braking or by coming sharply off the accelerator, causing weight to transfer away from the rear wheels. This often occurs when you enter a turn too fast; the solution is to enter more slowly, so that you can maintain your car's balance throughout the turn.

Oversteer in a rear-wheel drive car can also be caused by applying enough acceleration to break the rear wheels loose. This occurs most frequently under conditions of reduced adhesion (rain), but it can also occur under good conditions if your car is powerful enough. In this case, you must reduce your acceleration slightly to allow your rear tires to re-adhere. If you reduce your acceleration too much or too rapidly, weight will transfer away from the rear, and your car will continue to oversteer. To avoid inducing oversteer, it's important to apply acceleration smoothly and progressively. Remember: anything you do to upset your car's balance may transfer enough weight to cause understeer or oversteer. That's why we will emphasize smoothness throughout your school.

We've designed five exercises that demonstrate weight transfer in various ways. Your skidpad sessions are also designed to demonstrate understeer and oversteer and the techniques used to overcome them.

Where to Look

Whenever you're driving, you should watch where you're going. This seems obvious, but you'd be surprised how much time you spend looking at where you are, e.g., at your hood or at the bumper of the car in front of you. At the school, we've marked the exercises with pylons, and it's very important not to look at the pylon you're passing but rather at the next pylon coming up. Because of the delay between the time you see something and when you react to it (called your reaction time), you must look and think ahead to avoid problems. The farther ahead you look, the more time you have to react to trouble, and the easier it will be to avoid.

Morning On-Track Exercises

Just prior to your on-track session, we will have you bring your car down to the "false grid" and line up to await your instructor, who will join you before you start. Only one car at a time is allowed to run a given exercise, so instead of having everyone wait in a long line at the first exercise, we will break your group into fourths. You may be directed to bypass one or more exercises before you start your session; your instructor will tell you at which exercise you will begin.

There will be double pylons, called staging points, at the side of the track before each exercise; most will be manned by course workers. Except when initially bypassing, come to a full stop at each manned staging point until directed into the exercise by the worker. The two threshold braking exercises (Exercises 4 and 7) have staging pylons but are unmanned. You only need to stop at an unmanned staging point if the exercise is occupied; otherwise, proceed past the staging point immediately.

Exercise 1--Slalom (Pit Straight)

Straight Slalom ExerciseA slalom is a set of spaced pylons located on the centerline of the track. The object is to drive around the pylons, alternately passing them on the left and right, while holding a constant speed. After each successful pass though the slalom, increase your speed a little bit.

As your speeds increase, you'll find it harder to avoid running over the pylons. This is because your car requires a finite amount of time from the moment you turn your steering wheel until your car actually changes direction (called the transient response time). First, the sidewalls of your tires must flex. Then the springs and bushings in your suspension must compress. Finally, your car will begin to change directions. The faster you go, the more distance you cover before your car reacts to your steering input.

The key, then, is to anticipate this delay in your car's reaction and turn slightly before you reach the next pylon, much as a skier turns his skis just before a gate. The faster you go, the earlier you will have to turn.

When you turn your car from side to side, you are transferring weight to alternate sides of your car. In doing so, the springs on the side opposite the direction you're turning (called the loaded side) will compress. Until your suspension has fully compressed, your loaded-side tires will not achieve full adhesion. Final compression will occur most rapidly if the turn is executed smoothly; if you turn abruptly, your loaded-side springs will actually compress too much, then expand again (or rebound) before finally settling down. During this time, you will not have effective control of your car.

If you enter the slalom too quickly, you will find that you must slow down to negotiate the first turn. However, when you decelerate, weight transfers forward, and your rear tires lose adhesion. If enough weight transfers forward, you could spin.

Moreover, any errors in placement that you make will multiply at each turn. That is, if you are late turning for the first pylon, you will have to make a sharper turn at the second to avoid hitting the pylon. If you're going too fast, you won't be able to make the turn sharp enough, so you'll be late for the second as well, and the third turn will have to be even sharper. This can easily cascade, and unless corrected, you may run off the pavement near the last pylon.

To execute the slalom properly, you must enter at a speed slightly slower than you think is necessary, smoothly turn the steering wheel slightly ahead of each pylon, and maintain or slightly accelerate to keep the weight balanced from front to rear. If you find yourself going too fast, recognize the symptoms early and abort the slalom by straightening your wheel instead of turning back for the next pylon. Run over one or more pylons if needed but maintain control of your car.

Once you're through the slalom, proceed slowly around Turn 1 and through the Esses to the staging point for the next exercise, which is another slalom, but this time in a turn.

Exercise 2--Slalom Through a Curve (Turn 4)

Increasing-Radius Slalom Exercise The second exercise is similar to the first, but this time, you'll be going through a curve at the same time. When driven counterclockwise, Turn 4 is an increasing-radius turn; that is, it starts "tight" and gets easier to negotiate as you go through it. However, you'll be negotiating a slalom as you drive through the turn. Whereas the straight-line slalom requires you to steer right and left with a similar amount of steering input in each direction, this slalom will require much more steering input and effort to turn left than to turn right. This is because the road curves to meet you when you turn right. As with the straight-line slalom, smoothness and proper entry speed are the keys.

Because the turn radius increases, you should accelerate smoothly through the slalom, as each turn will get progressively easier. Note that more weight transfer will occur when you turn to the left, and your car's transient response will be correspondingly longer, so time your steering inputs accordingly.

Exercise 3--Braking While Turning (Turn 5)

Brake and Turn ExerciseThis exercise is designed to illustrate that braking and turning simultaneously requires a tradeoff between stopping ability and cornering ability. You will have to split the friction available to your tires between slowing your car and changing directions. You control this split by how much pressure you put on your brake pedal.

When you get to the first pair of pylons, switch from acceleration to maximum braking and steer the car toward the second set of pylons. Try to come to a complete stop before reaching the second set. Remember from the slalom that you must anticipate your car's transient response time by turning slightly before the first pylons.

Note also that your car's weight will be transferring forward from braking, as well as to the right from turning. This means that your right-front tire will be most heavily loaded (generating the most friction), and your left-rear tire will be most lightly loaded (generating the least). If you detect the rear tires losing adhesion, reduce your braking pressure; this will transfer weight back to the rear and increase their adhesion.

Exercise 4--Threshold Braking (Outside Straight)

Thresold Braking ExerciseThis exercise gives you a chance to practice threshold braking. Accelerate briskly down the outside straight toward Turn 6. When you reach the first of the pylons, begin braking and try to come to a stop as quickly as possible without locking up your tires or engaging your ABS. The row of pylons at the edge of the track will serve as a "gauge" of how quickly you've stopped. The faster you approach the braking pylons, the longer your braking time will be, giving you more practice time.

The proper technique is to build brake pressure rapidly to a maximum just shy of locking your tires or activating your ABS. If you overdo it, don't jump entirely off the pedal. Instead, modulate your pedal pressure by reducing it just enough to release your tires or stop the ABS activation. With practice, you'll get a feel for exactly how much foot movement you need.

You will want to concentrate especially on minimizing the transition time, that is, the time it takes you to switch from acceleration to full braking. This time directly translates into distance covered, and the faster you react, the shorter your braking distances will be.

Afternoon On-Track Exercises

In the afternoon, we'll be doing exercises similar to the morning, but we'll be going clockwise around the track so that the turns will come up in descending order. We'll begin the session as we did in the morning by dividing the group and bypassing some of the exercises before starting.

Exercise 5--Obstacle Avoidance (Pit Straight)

Obstacle Avoidance ExerciseIn this exercise, you'll simulate making a last-second maneuver to avoid an obstacle. The track will be divided into two lanes. Approach the exercise by driving down the center of the track toward the center pylons. At the last moment, your instructor will either say "left" or "right" or point to the lane you are to use. Steer into the lane your instructor indicates and continue through the exercise without braking.

You will have to manage weight transfer and your car's transient response time. You will also have to look ahead, because if you stare at the first center pylon, you will not know how much to turn the steering wheel to enter the designated lane. Instead, focus on the last center pylon and be prepared to shift your vision to the last pylon on the right or left as needed. Use your peripheral vision to guide your car into the proper lane.

Try to remain relaxed and alert as you approach the exercise, and try not to decide which way you're going before your instructor tells you. With each pass, your instructor will delay his command more. If he fails to tell you which way to turn, he will expect you to run over the center pylons!

Exercise 6--Lane Change (Turn 6)

Lane Change ExerciseAs you exit Turn 6, drive between the first pair of pylons on the left side of the track, and then steer to the right toward the second pair. As you reach them, steer left to straighten out the car and pass between them. As you pass through the third pair of pylons, steer left again toward the fourth pair. Finally, steer to the right while passing between the fourth pair and exit the exercise. Maintain constant speed through the exercise, and increase your speed slightly with each successful pass.

Our familiar friends, weight transfer and transient response time, are in operation here. The key is to allow your car time to settle, i.e., restore its balance by redistributing its weight evenly, between the second and third pair of pylons. If you enter too quickly, your car will still be unbalanced when you attempt to turn back for the last pair of pylons, and it will be sluggish in turning (i.e., the transient response time will be longer). If that happens, do not attempt to force your car through the fourth set of pylons; if you attempt to slow down, you may transfer enough weight off the rear tires to spin. Instead, simply abort the exercise by straightening the steering wheel and driving past the pylons.

Exercise 7--Threshold Braking (Outside Straight)

Thresold Braking ExerciseThis exercise is identical to Exercise 4 from the morning, except that you're going in the opposite direction toward Turn 5. If the exercise is clear when you exit the Lane Change, accelerate past the unmanned staging point. As you pass the first of the gauge pylons, switch from acceleration to braking and try to come to a complete stop as quickly as possible. Use the pylons at the edge of the track to measure your progress.

Exercise 8--Slalom Through a Curve (Turn 4)

Decreasing-Radius Slalom ExerciseAlthough this is the same setup as Exercise 2, it will prove to be a lot harder to master. Traveling clockwise, Turn 4 is now a decreasing-radius turn, and you'll find that you will need a little more steering input for each pylon. In the morning, you needed to enter the slalom slowly and accelerate as you traveled through it. Now you'll need to gradually lose speed as you travel through the slalom, so that the slowest point is at the last pylon. The same principles of weight transfer and transient response time are at work here, but they will be magnified as the turn tightens up sharply near the final pylons.

Skidpad

Before your skidpad session, we'll have you line up on the false grid on the opposite side than you used when preparing to go out the track. Once we get the whole group together, a skidpad instructor will lead the group down to the skidpad. Please be on time for your skidpad sessions, as we have to hold up the next on-track group until the last car has cleared the track for the skidpad. If you arrive too late (after the next on-track session has started), you'll miss your session, as the only access is from the track.

Our skidpad program is explained in detail in the accompanying Skidpad Instruction publication. Most students are a bit nervous about their first skidpad session, but virtually everyone finds them immensely rewarding and instructive. You have a very rare opportunity; most other BMW CCA chapters cannot offer skidpad training, and this training directly enhances your ability to control your car. If you have any questions about the skidpad or our program, please do not hesitate to ask.

Things to Remember

First and foremost: maintain control of your car at all times. The best way to learn your car's limits--and the only way we want you to learn them--is by working up to them. If you drive "over your head," you're not going to learn anything, and you're going to endanger yourself and others in the process.

Second, be aware of what's going on around you. You'll need to listen to your instructor, but you'll also need to watch out for our course workers and other drivers. We don't want you running over our workers; they're hard to replace!

One last thing to remember: the Highway Safety School is supposed to be fun. It's only natural to be nervous at the start, but as you concentrate and learn, you'll soon find that adrenaline and exhilaration replace the butterflies. Pace yourself and enjoy the school!

Revised May 1999

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