The IPDE Process
Nearly every driver uses some kind of system or process to drive.
Drivers who do not use some kind of organized system will have more
close calls and collisions. Drivers who use an organized system
will be better equipped to manage risk and therefore reduce the
possibility of damage or injury.
All activities throughout a person’s life involve some degree
of risk. Whether playing a sport, working on the job or driving
a vehicle, some degree of risk with the possibility of injury is
always present. The risk you take when driving a car is the ever-present
possibility of conflict.
Driving a car in today’s environment can cause you to be
at a very high degree of risk. Risk factors can be contributed by
the driver, by the vehicle, and by the roadway and environment.
Some examples of driver-contributed factors are: adjusting the radio,
road rage, having blurred vision, drinking and driving or using
a cell phone.
Driver-contributed risk factors also apply to other drivers on
the road. These other drivers can increase or decrease your level
of risk and chance of conflict.
Some risk factors are contributed by the car. However, most vehicle-related
risk factors are really contributed by the vehicle owner. Ownership
responsibility requires proper maintenance and repair of your car.
Some of these risk factors are: bald fires, poorly adjusted brakes,
dirty windshield, broken headlight, and worn wiper blades.
Risk factors contributed by the roadway and the environment may
include the following: bright sun, construction, dark shadows, snow
and ice or a sharp curve.
As you drive, be aware that all of these risk factors, and many
more, play a major role in the level of risk you face.
Because some degree of risk is always present, try to make sure
nothing about your own condition or the condition of your vehicle
raises your level or risk.
Some drivers deliberately take chances. They put not only themselves
but others at a high degree of risk. Deliberately taking a chance
with a vehicle, with its great capacity for harm and destruction,
should be unthinkable. The potential for suffering harm is too great,
and the possible penalties are too serious.
THE IPDE PROCESS
Good seeing habits and your ability to manage space in the roadway
are basic tools for low-risk driving. The IPDE Process, along with
the Smith System and Zone Control System, can enable you to enjoy
low-risk and low-stress driving.
Safe driving depends upon your ability to see and analyze traffic
situations correctly. Good seeing habits are the basic critical
factor necessary for staying out of high-risk situations. However,
just being ale to see well is no guarantee you will identify all
critical clues and make correct driving responses in every situation.
The driving task is primarily a thinking task. Your hands and
feet do only what your brain tells them to do. Most responsible
drivers use a system that deals with all the traffic possibilities
they will encounter. These drivers have fewer close calls and accidents
than drivers who do not use some kind of system.
The IPDE process is an organized system of seeing, thinking, and
responding. The Smith System and the Zone Control System will help
you apply the IPDE process. The four steps of the IPDE process are:
You begin the IPDE process by “reading” traffic situations
to gather information for your decisions and actions. To process
this information properly, you must identify hazards and predict
conflict. You then decide how to avoid the conflict by executing
the correct action.
The Smith System is an organized method to help drivers develop
good seeing habits by using five rules for driver safety. The five
rules of the Smith System are:
- Aim high in steering.
- Keep your eyes moving.
- Get the big picture.
- Make sure others see you.
- Leave yourself an “out.”
The Zone Control System is an organized method for managing six
zones of space surrounding your vehicle. Zone Control allows you
to see and respond to changes in the traffic environment at a time
when best control can be achieved.
The structure of the Zone Control System includes the following
- See a zone change.
- Check other zones.
- Create time and space by getting the best speed control, lane
position, and communication.
Using the Smith System and Zone Control System with the IPDE process
can put you well on the road toward low-risk driving behaviors.
IDENTIFY AND PREDICT
The Identify and Predict steps of the IPDE process are critical
in every driving environment. These two steps begin your thinking
process for every situation you encounter. With practice and experience,
these steps will seem to occur in your thinking process as happening
almost at the same time. As you search in and around your path to
identify possible problems, you will be making judgments and predictions
about what conflicts may occur.
The first step of the IPDE process is identify. This step involves
much more than just seeing. When you identify, you give meaning
to what you see. You must know when to look, where to look, how
to look, and what to look for.
Any aspect of the highway transportation system can become a hazardous
situation. This includes the roadway, your own vehicle, other vehicles
or pedestrians, and traffic controls. Clues you identify may cause
you to change direction or speed, signal others, or perform any
combination of maneuvers. The sooner you identify a possible hazard,
the more time you will have to react safely.
and Searching Ranges
The Zone Control system helps you make quick and accurate use
of the IPDE process by setting a standard of what to identify and
what to do when you find it. A zone is one of the six areas of space
around a vehicle that is the width of a lane and extends as far
as the driver can see. The picture shows the six
zones around your vehicle. Straight ahead is the front zones, to
the left is the left-front zone, and to the right is the right-front
zone. Behind you is the rear zone, the left-rear zone, and the right-rear
An open zone is space where you can drive without a restriction
to your line of sight or to your intended path of travel. Your line
of sight is the distance you can see ahead in the direction you
are looking. Your intended path of travel is the space your vehicle
will occupy. Your path of travel is directed toward the target areas.
The target area is the section of the roadway where the target is
located in the center of your intended path, and the area to its
right and left.
The closed zone is a space not open to you because of a restriction
in your line of sight or intended path of travel. A red traffic
light is an example of a closed front zone. A parked vehicle to
your right represents a closed right-front zone. A closed rear zone
might be a vehicle that is following you too closely. The sooner
you identify a closed zone, the more time you have to respond. With
more time, the better chance you have to achieve control of the
situation by lowering the degree of risk.
In order to keep alert to the conditions of your zones, there
are three searching ranges that need to be evaluated. A searching
range is a certain distance ahead of the vehicle where the intended
path of travel is systematically evaluated.
Next you will search the 12-15 second range, which is the space
you will travel in during the next 12-15 seconds. This range is
where you need to identify changes in your line of sight or path
of travel to make decisions about controlling your intended path.
Try to identify the possibility of closed zones by searching to
the left and right for anything that might come into your zones.
The 4-6 second range is the space you will travel in during the
next 4-6 seconds. This range is where you need to get the final
update of how you are controlling your intended path of travel.
Orderly Visual Search Pattern
You can use any of several patterns to help develop your own identifying
process. An orderly visual search pattern is a process of searching
critical areas in a regular sequence. The use an orderly visual
search pattern, look for clues in and around your intended path
of travel in a systematic manner. Below is an example of an orderly
visual search pattern for straight-ahead driving.
- Look ahead to your target area range.
- Evaluate your left-front, front and right-front zones in the
12-15 second range. Search driveways and intersections for possible
changes in your line of sight and path of travel.
- Glance in rearview mirror to check your rear zones.
- Evaluate your 4-6 second range before entering that space.
- Look ahead again to evaluate another 12-15 second range.
- Check your 4-6 second range.
- Glance in rearview mirror.
- Check speedometer and gauges.
You will repeat this pattern continually as you move forward. Each
look or glance should last only an instant as you evaluate your
zones and the areas to the left and right. Be careful not to stare
as you search. Practice using your orderly visual search pattern
as a passenger – in addition to when you are driving –
so it will become a safe driving habit. You will then be able to
adjust your search pattern for any maneuver or driving environment.
Where and How to Look
Different driving environments and traffic situations present
a variety of visual search problems. As you gain driving experience,
you will learn what kinds of clues and situations are most important
to identify in order to keep an open zone in your path of travel.
The area you can see around you, while looking straight ahead,
is called your field of vision. Many of us can see an area of about
90 degrees to each side, for a total picture of 180 degrees. The
area you can see clearly and sharply is seen with your central vision.
This is a narrow cone of only up to 10 degrees. The area you can
see to the left and right of central vision is your side vision,
or peripheral vision. As the distance from central vision increases
toward the outer edge of peripheral vision, the less clearly you
can identify clues and events.
Three of the Smith System rules can help you learn where and how
to look as you develop your visual search pattern.
Aim High in Steering
To “aim high” means to look ahead 12-15 seconds into
your target area as you drive. Do not just look at the close area
in front of or at the sides of your vehicle. Looking far ahead with
your line of sight will help you to identify clues and analyze situations
before your zone becomes closed. There are many types of restrictions
to your line of sight that can cause a closed zone. Some such restrictions
are curves, hills, large vehicles, weather conditions, buildings,
trees, or even a dirty windshield.
You see most clearly in the area of central vision, but
peripheral vision is equally important.
Keep Your Eyes Moving
Looking near and far, side to side, and in the mirrors, will help
you see a zone change before it becomes critical. Keeping your eyes
moving does not mean just moving them constantly. You must fixate
on an object or an event for an instant in order to identify it.
Do not fixate for longer than an instant or you will find yourself
staring. Keeping your eyes moving will prevent you from staring
at any one object or clue.
Develop the art of scanning, glancing continually and quickly
with very brief fixations through your orderly visual search pattern.
You are looking and seeing as you scan, but not staring at any one
event or clue. Staring blocks out side vision, causes lack of attention,
and tends to create high-risk driving habits. Keeping your eyes
moving helps you stay more alert with your attention at a higher
level. You are then more likely to keep up with all the changes
in your field of vision.
Get the Big Picture
Getting the big picture is the mental process of putting together
the critical clues you have selected. It is the result of aiming
high and keeping your eyes moving.
What to Look For
Knowing where and how to look does little good if you do not know
what to look for in your target area. Develop the technique of selective
seeing in your identifying process. Selective seeing means that
you identify and select only those clues and events that restrict
your line of sight or can change your intended path of travel.
Look for Open Zones
Use your visual search pattern to look for specific driving-related
clues that might cause an open zone to close. When searching parked
cars on a street, you might identify an important clue, such as
front wheels turned toward the street. You might also identify vapor
coming from an exhaust pipe or a driver sitting in a car. These
clues indicate that a car might enter your path of travel and cause
your front zone to close.
The kinds of clues you search for will change as you drive in
different environments. When driving in the city, search for intersections,
parked cars, pedestrians and traffic. On open highways, search areas
much farther ahead. Look for crossroads, slow moving vehicles and
animals. Any of these can suddenly cause an open zone to close,
resulting in the need to change your intended path of travel. When
you drive on expressways, speeds are higher and scanning all zones
becomes even more critical.
Regardless of the driving environment, you should always look for
other roadway users, roadway features, changing conditions, and
traffic controls that may affect your intended path of travel.
Look for Other Users
Look for other users who might affect your intended path of travel.
Watch for movement of other users, especially in areas that have
shadows or shade. Watch for pedestrians and bicyclists. A large
truck is easy to identify. However, it creates a restriction in
your line of vision and may prevent you from seeing another user.
Develop the habit of ground viewing as part of your visual search
pattern. Ground viewing is making quick glances to the roadway in
front of your vehicle. When other vehicles are approaching, use
ground viewing to see where they are headed by checking the direction
of their front wheels.
Always be on the lookout for problem drivers. Problem drivers
usually give clues by their driving behavior. Some fast drivers
might be problem drivers. They may try to pass without enough room
or in a no-passing zone. They frequently change lanes, trying to
get ahead of the normal traffic flow, and can cause a sudden change
in your open zone condition.
Look for Roadway Features and Conditions
The roadway itself is another important area to watch. Identify
intersections, hills and curves early. Be aware ahead of time that
the width of your lane might be reduced for road construction or
other obstacles. An intersection is a high-risk area where the management
of your path of travel needs constant attention. Stopped traffic
or entering traffic can cause line-of-sight restrictions or even
a closed zone. A hill is a line-of-sight restriction which could
hide a closed zone as you go over the hill. Some examples of changes
are: change from multilane to single lane, such as in construction;
change in width of lane, such as in construction; roadway surface,
such as rain or icing on bridges, etc.; roadside hazards, such as
other objects entering your lane of travel.
Look for Traffic Controls
Learn to look in different places for traffic controls. At major
intersections, controls can be overhead, in the center, or on a
corner. Identify traffic controls as early as possible so you are
ready to make correct responses.
Once you have identified a hazard, predict how this hazard might
affect your intended path of travel. When you predict, you interpret
the information you have identified. You predict where possible
points of conflict can occur. You try to foresee what might happen,
how changes in zones may occur, and how you would check other zones
for alternate paths. Your predictions will be based upon those conditions
that may reduce your line of sight or could change your intended
path of travel.
If you had to face just one hazard at a time, you could more easily
predict the possible outcome. However, most of the time you will
be faced with more than one possible hazard or conflict, so predicting
can become more complex.
How to Predict
Predicting involves what is happening in your zones, what could
happen, and if it does happen, how the change could affect you.
To predict you must evaluate the situation and make a judgment about
the possible consequences. The more complex a situation is, the
more difficult it is to identify and predict. As you gain driving
experience, you will become more selective about which hazards or
possible conflicts are critical.
One basic part of your driving knowledge comes from the study
of traffic laws and driver-education material. Whenever you drive,
you also gain knowledge by gathering more information and learning
Making a judgment about a traffic situation involves measuring,
comparing and evaluating. As you drive, you judge speed, time, space,
distance, traction and visibility. You make judgments about your
own driving performance as well as the actions and performance of
other roadway users. Make every effort to develop the ability to
make sound judgments that lead to accurate predictions.
In addition to knowledge, experience helps you improve your ability
to predict accurately. Exposure to a wide variety of driving experiences
provides a solid base for making sound judgments later.
What to Predict
Nearly all predictions you make as a driver will be related to
predicting changes in zones and looking for an “out”
or an alternative path of travel. Two major elements in the traffic
scene you must make predictions about are:
- The actions of other roadways users
- Your control of your vehicle and consequences of your actions
Predicting Actions of Others
Do not assume other roadway users will always take the correct
action. Instead watch for clues to what they might do to alter zone
conditions. The most important types of predictions to make concerning
the actions of others are:
- Path – Where might the other driver go? What zone might
have closed? Will I have an open zone for an “out”?
The Smith System rule of leaving yourself an “out”
is critical when predicting possible closed zones.
- Action – What action will other users take? Is more than
one action possible? Where will I be then?
- Space – Will I have an open zone?
- Point of Conflict – If I have no open zone for escape,
where might our paths cross and a conflict occur?
Predicting Control of Your Vehicle and Possible Consequences
Speed is probably the most important factor in maintaining control
of your vehicle. Always be prepared to adjust your speed for different
zone conditions and situations. Different traffic, roadway, and
weather conditions can change the amount of time and space needed
for safe reactions.
The basic requirement for vehicle control is traction. Traction
is the actual gripping power between the tires and the roadway surface.
The more traction there is, the greather the gripping power.
DECIDE AND EXECUTE
Once you have identified a situation and predicted a possible
conflict, you then decide upon an action. Deciding, like predicting,
is also a mental task. There is probably no task more important,
though, than making wise decisions and then executing actions to
avoid conflict. Drivers must continually identify and predict until
they have enough information to make correct decisions.
Once you make a decision, the execute step of the IPDE process
will follow. To execute a decision means that you carry out an action
that you have decided upon. In order to do this, you will use your
vehicle’s controls and safety devices.
As you follow a selected path, your decision might be to maintain
speed, change speed, change direction, or communicate your plan
to others. Or you might decide to use a combination of these actions.
Be prepared to rethink your decisions as zones close and greater
hazards are presented. Practice and experience, as well as your
judgment and stored knowledge, are the tools you can use to avoid
conflict and develop low-risk driving behaviors.
Decide to Change Speed
Any decision you make will be influenced by the speed of your
own vehicle as well as the speed of other vehicles. Many drivers
think that slowing down is the only way to avoid a collision. In
many situations, however, you will decide to maintain your speed.
Your other choices of actions, rather than maintaining your speed,
are to decelerate, brake, or accelerate. Base your decision about
speed control on your evaluation of the situation as well as the
possible consequences of your actions.
Decide to Change Direction
In order to change your position in the roadway, you will steer
to the right or left. A greater change of direction might even be
a lane change.
The Smith System rule to leave yourself an “out” allows
you to change direction when necessary. You then can use an escape
path into an open zone to avoid conflict. This area of space all
around your vehicle is called a space cushion.
Three different lane positions are available to you within your
lane. You could change to one of these positions in order to avoid
a closing zone. Notice the three lane positions in the diagram below:
- Lane position 1: The car is centered within the travel lane.
This should be your selected and safest position under normal
driving conditions. In the position you have the most space around
- Lane position 2: The car is three to six inches away from the
left line of your lane. You might decide to use this position
when there is a closed right-front zone with an open left-front
zone. Just a slight adjustment of the left is necessary.
- Lane position 3: The car is three to six inches away from the
right line of your lane. Use this position when there is a closed
left-front zone with an open right-front zone.
There may be times when the situation requires a greater change
in direction than the three lane positions. You may decide that
the best position, in some situations, is to straddle a lane line.
In these situations, return to lane position 1 as soon as it is
safe to do so.
In order to make consistently low-risk decisions, try to detect
a changing zone condition at least 12 seconds ahead of your searching
area. This gives you ample time to decide on the best action.
Decide to Communicate
Communicating is the process of sending and receiving messages
to and from other users of the roadway. The decision to communicate
with others helps reduce the possibility of conflict. The Smith
System rule, “Make sure others see you,” tells others
where you are and what you plan to do. You can decide to communicate
with others by using lights, horn, vehicle position, eye contact,
and body movement.
A change in direction or speed can be executed with less risk
if you have communicated your intentions to other users. Try to
avoid changes in speed or direction without communicating first.
Surprises of sudden actions can result in high-risk situations.
You can decide to communicate with others in a variety of ways:
- Headlights, taillights, and brake lights
- Turn signals
- Parking lights and hazard flashers
- Back-up lights
- Car position
- Eye contact and body movement
After deciding the best method of communicating, you will execute
that action to inform others of your decision.
The IPDE process, the Smith System, and the Zone Control System
will help you make decisions that will enable you to avoid hazards
and conflicts in your intended path. The safest position in traffic
is the place where the fewest vehicles surround you. Your objective
is to keep your vehicle surrounded by space. Continually analyze
your left, front and right zones and make decisions to adjust your
speed or direction if one of your zones begins to close. By decision
to adjust your speed or direction, you will avoid unnecessary stops
and thus reduce your risk of conflict.
Minimize a Hazard
You always want to minimize a hazard, or reduce the possibility
of conflict by deciding to put more distance between yourself and
There will be times when you face more than one hazard at a time.
When this occurs, do not try to handle both or all hazards at once.
Instead, decide to adjust your speed so you deal with only one hazard
at a time. By following this strategy, you will separate the hazards.
Sometimes hazards cannot be minimized or separated. When this
occurs, you must decide to compromise space by giving as much space
as possible to the greater hazard.
Carrying out your decision in order to avoid conflict is the execute
step in the IPDE process. This step involves the physical skills
used in driving. In most cases, you will execute routine actions
and maneuvers. Some actions will be using your vehicle’s controls
such as heater, defroster, wipers, gearshift lever, and others.
More important actions, however, involve timing and placement of
your vehicle to avoid conflict. The important actions you will execute
- Control speed
Your decisions to control speed can result in a variety of actions.
Sometimes the action you take will be to maintain the speed you
are going. Other times your action may be to decelerate. This action
can be used successfully as you approach a red light. If you merely
release the accelerator far enough before the intersection, you
often will arrive at the intersection when the light is green. In
this situation, you also may use gentle pressure on the brake if
more slowing is needed. Check your rear zone before decelerating.
When greater deceleration is needed, you will execute the action
of more firm braking. The amount of braking needed will vary with
the situation, the speed of your vehicle, the condition of the roadway,
and the condition of your brakes.
Always check your rear zone before decelerating or braking in
any manner. Avoid locking the brakes in an emergency stop. Locked
brakes making steering impossible because wheels must be turning
to provide traction for steering. Most vehicles have vehicles with
anti-lock braking systems. Such a system helps prevent loss of steering
control. An antilock braking system, through the use of computers,
helps brake your vehicle in an emergency. All you need to do is
to apply the brakes hard, continually. No pumping action is needed.
When you decide to steer away from a possible conflict, execute
just the amount of steering needed. Oversteering can cause you to
lose control of your vehicle, especially at higher speeds. Higher
speeds also require more space for your maneuver.
Understeering can also present a problem. Try to steer just enough
to avoid a conflict without making jerky or sudden movements. Drivers
who keep space cushions around their vehicles usually have an escape
path to steer into, thus reducing risk.
In many instances your only action will be to communicate. When
you do communicate, you must do it early enough so other users know
your intentions. Communicate by using the following:
- Headlights, taillights, and brake lights. Use headlights during
periods of reduced visibility. Using headlights during daylight
hours is a safety practice that makes your vehicle more visible
to other drivers. Some new vehicles are equipped with daytime
running lights – headlights that come on automatically whenever
the vehicle is operated. The advantage of these lights is to improve
the visibility of the vehicle.
- Turn-signals. Turn them on three to five seconds before making
any change in direction.
- Parking lights and hazard flashers. When you are parked along
the roadway but not in an emergency situation, have your parking
lights turned on. If your vehicle is disabled, turn on your hazard
flashers. Be prepared to change your path of travel when you see
the blinking or flashing lights of a stopped delivery truck.
- Back-up lights. White back-up lights let others know you are
backing up. Look for back-up lights on vehicles in parking lots.
- Horn. A light tap is usually enough for a warning. In an emergency,
a loud blast may be necessary.
- Vehicle position. The position of your vehicle in the roadway
communicates a message. It indicates to others your intended path
of travel. Other drivers may or may not see a light signal, but
the position of the vehicle in the lane sends a message
- Eye contact and body movement. Try to develop eye contact with
other roadway users. You can communicate many messages this way.
Body movements such as a wave of the hand may tell a driver to
You often will need to execute a combination of actions. Sometimes
you might need to accelerate and steer at the same time. In other
situations, you might need to brake, communicate, and steer at the
USING THE IPDE PROCESS
Using the IPDE process, along with the Smith system and the Zone
Control System, helps you plan and execute maneuvers to reduce hazards.
It is up to every driver to manage space, time and speed in order
to further increase safety within the highway traffic system.
You must continually practice using the IPDE process so that it
will become habit. Once you have developed the habit, you will
- See more
- Make accurate predictions and correct decisions
- Execute maneuvers more successfully
IPDE Takes Practice
Practice is necessary for the development and improvement of any
skill. As you ride with other drivers, practice the I-P-D steps
of the IPDE process. You can then judge if the actions taken by
others were based on correct decisions.