TECHNIQUES IN AVOIDING COLLISIONS – EMERGENCY MANEUVERS
LESSON #11
The purpose of this study sheet is (1) to acquaint you with the techniques of
emergency maneuvering, (2) to help you develop the ability to recognize the
situations where these maneuvers can be used, and (3) to identify some potential
dangers involved in using these maneuvers in traffic. By the end of this study
sheet you should have acquired a base or background of knowledge concerning
emergency maneuvers that will allow you to make alternative decisions when
confronted with potential conflicts.
Emergency situations develop every day you drive. Since you have little
control over other drivers and sometimes you, yourself, will make driving
errors, it is almost impossible to predict when these situations will arise. In
order to be prepared for these situations you, as a driver, must have a
background of knowledge concerning emergency maneuvers which will allow you to
take appropriate action when confronted with these emergencies. On the following
pages you will cover the techniques used for various emergency maneuvers,
general situations where these maneuvers could be used, and some of the dangers
involved in each.
This study sheet is to be used with Worksheet W11b. The sections in each
correspond to the sections in the other. It would be easiest if you completed
the worksheet as you are reading the study sheet.
Section 1 – CONTROLED BRAKING:
In order to be skillful in the use of controlled braking, you must be able to
move your right foot from the accelerator to the brake "as rapidly as
possible" and then push down on the brake as fast and as firmly as you can,
without having the tires skid.
The technique of stopping in an emergency without skidding the wheels is
known as controlled braking. The controlled braking technique is often difficult
to learn, for many reasons. Since, from the beginning of the course, you have
been instructed to brake gradually, you are conditioned not to hit the brake
hard or in an emergency you may tend to brake too hard and skid the tires
causing the car to take longer to stop. In some situations you must prepare
yourself to do this. Practice in this technique, even mental practice, is
necessary to overcome the urge to make a slow, smooth stop.
The controlled braking technique is useful in situations where something is
directly in front of your vehicle. These situations come up most often because
you, the driver, are not paying enough attention to your task, or you are
distracted by some other factor. The negligence of other drivers is another
factor which causes these situations to develop.
Section 2 – QUICK STEERING:
Often, when confronted with emergencies, you may find it necessary to steer
quickly to avoid a crash. To prepare yourself for this maneuver, you must first
determine which hand position on the steering wheel will give you maximum
control. Normally, you are encouraged to use the 10-2 position for the best
control under most driving conditions.
Basically, what is important, is that you have your hands balanced on the top
half of the steering wheel.
In order to use any technique you must be preparing for predicting
emergencies to develop. Quick vision checks for side hazards must be made prior
to a quick steering maneuver.
In many emergencies, steering can be more effective than braking to avoid
conflict with obstacles. The use of quick steering when faced with a hazard
approaching from the side, will allow you to get space to maneuver, provided the
new path you select is clear. Some situations where this technique might apply
are (1) a vehicle door opening in front of you, (2) a pedestrian stepping out
from between parked vehicles, or (3) a vehicle pulling into an intersection,
when you have the right of way.
Section 3 – QUICK STEERING & CONTROLLED BRAKING
Some situations will call for a combination of the two techniques mentioned
before. The technique for this maneuver is generally the same, but we must
consider that we are now doing two different things at the same time. These two
things, steering and braking, require us to more two different parts of our body
in two different directions. This will force us to give more attention to
controlling the pressure on the brake to prevent skidding, and controlling the
movement of the steering wheel to prevent over steering. A driver will have a
tendency to over steer if he/she will have a tendency to over steer if he/she is
too close to the obstacle.
Two situations where the quick steering and controlled braking techniques are
used are (1) when an on-coming vehicle pulls into your lane, or (2) when a
vehicle changes lanes suddenly in front of you, forcing you to maneuver.
Controlled braking and quick steering are useful in situations where
controlled braking alone will not avoid a collision, and then the steering
adjustments help to avoid the accident.
Section 4 – QUICK ACCELERATION:
The quick acceleration technique is used at times when you have judged that,
by moving faster, you can avoid a conflict. To use this technique, you must snap
your foot down on the accelerator (gas pedal), to force the vehicle to quickly
pick up speed. How much pressure you use on the gas pedal will depend on the
performance capabilities of your vehicle. If you have a high-performance sports
vehicle, the pressure will not be very much. If you have a small engine, compact
vehicle, you may have to push the gas pedal down as hard as you can. This
technique should be accomplished without spinning the tires for maximum
traction. The use of quick steering in combination with quick acceleration may
be necessary in some cases, to avoid a conflict, where slowing down or keeping
your speed may increase your chances of having an accident.
Generally, quick acceleration is useful in situations where other vehicles
are moving toward your vehicle, and where keeping the same speed, or slowing
down, will make it more likely for you to have an accident.
Section 5 – SKID CONTROL:
Skidding is a fact of driving that plays a big role in traffic accidents.
Since tires are the points where the vehicle comes in direct contact with the
road, anything the vehicle does, including any skidding, is ultimately
translated through them.
Friction, the "grip" between the tires and the road, allows the
vehicle to start, stop, and/or corner. There are three types of friction
involved with a car and driving, static, rolling or dynamic, and sliding.
There is a greater amount of friction between a stationary wheel and the road
than there is between a sliding wheel and the road. Picture a vehicle parked on
an icy hill. The brakes are locked so that the wheels cannot roll. It might take
three or four men to get the vehicle moving. When they do, it says in motion and
slides to the bottom of the hill. As long as the vehicle is not being pushed,
static friction keeps the vehicle from sliding down the hill. However, once the
men push hard enough to overcome the static friction, the vehicle continues to
slide on its own. This demonstrates that sliding friction does not grip the road
as well as static friction.
Now, let’s picture the same vehicle, with a driver in it, being pushed by
the same men – only this time the wheels are rolling, and the driver is
lightly braking, but not locking the brakes. With the men pushing the vehicle,
the wheels will continue to roll, because there is less friction between a
rolling wheel and the road than there is between a stationary wheel and the
road. When the men stop pushing, the vehicle comes to a stop, demonstrating that
there is more friction between a rolling wheel and the road than there is
between a sliding wheel and the road. This illustrates the value of keeping the
wheels rolling and not locking up brakes when stopping quickly.
Friction between the tires and the road is not always constant. Sand, or
water on the road, for example, decreases the level of friction. As your speed
increases, the friction between the tires and the road decreases. With decreased
friction for whatever reason, the possibility of skidding increases.
Although there is no one way to handle any particular skid, there are certain
rules and techniques that can be applied to help control skidding. Four basic
rules are:
Do not use your brakes until steering control is re-established.
Do not accelerate.
Depress the clutch, if you’re driving a manual shift vehicle.
"Counter steer" to correct for the skid.
As you read about the following skids, you’ll see why these four rules are important.
Section 5a - FRONT WHEEL BRAKING SKID
This skid results due to the fact that the front brakes are set up tighter
than the rear brakes. When you brake hard, the front wheels lock. As the vehicle
begins to skid, you suddenly find that you cannot steer, no matter how you turn
the wheels, and the vehicle continues straight ahead. Locked front wheels cannot
turn the vehicle.
When a vehicle is in a front wheel braking skid, all of the available
friction at the front tires is being used up by the skid. No cornering force can
develop. At the same time, the rolling rear wheels act as a "rudder"
to keep the vehicle going in a straight line. If you’ve stepped on the brakes
to steer around an obstacle, you’ll undoubtedly find the vehicle skidding into
whatever it was that you were attempting to avoid.
What can be done about this skid? You should get off the brakes. Let the
tires re-establish rolling friction.
Section 5b - REAR BRAKING SKID
In this skid, the vehicle can spin 180 degrees and end up going backward. It
occurs when the rear wheels lockup or brake loose in a corner. As soon as the
vehicle turns slightly, the rear wheels slide sideways and spin the vehicle
around. When this type of skid occurs, stay off the brakes and steer in the
direction you want the car to go. With the brakes off, the tires can keep or
re-establish rolling friction and, by steering, you should be able to bring the
vehicle back in line.
Section 5c - ALL WHEEL BRAKING SKID
This is one of the most common skids, the type of skid that occurs even if
the brakes are adjusted properly. It occurs when the driver jams on the brakes
too hard usually in a panic situation, causing all four wheels to lock and begin
to skid. The vehicle will, under these circumstances, slide unpredictably in any
direction.
Correcting this skid is easy to understand, but it is difficult to
accomplish. Simply get off the brakes and let the tires re-establish rolling
friction. This takes practice; for when a vehicle is in a violent skid, the
natural reaction is to brake even harder.
Section 5d - POWER SKID
This skid is the result of accelerating too fast for road conditions or on
curves. Power applied to the drive wheels overcomes the grip of the tires,
causing them to spin. When a tire is spinning, it has no friction to keep the
wheels from slipping sideways. Generally, the vehicle "fishtails"—swings
back and forth if going straight, and spins around if in a corner. A vehicle in
a power skid acts essentially the same as a vehicle skidding with its rear
wheels locked.
To control a power skid, ease up on the accelerator (gas pedal), let the
vehicle stabilize, and brake gently.
The most severe power skid can cause power spin out, triggered by
accelerating through a corner or sharp curve. The change from rolling to sliding
friction is sudden and violent: the vehicle may spin completely around several
times. Regaining control is very difficult. If you aren't ready for this
reaction, and don’t respond correctly immediately, the vehicle
will spin out of control. Attempt to regain control by keeping your foot off the
brake and gas pedal and then steer.
If the vehicle is simply going too fast, an it is obvious that you cannot
stay on the road, try to aim the vehicle for a clear spot where you can stop
without hitting anything, or try to hit as soft an object as possible. Steering
at the right time can make the difference between hitting a tree and skidding
into an open field. Braking may not be helpful in this situation. Above all, to avoid
getting such a situation, remember to slow down prior to going into a
turn.
Section 5e - SPIN OUT
Spinouts may occur as a result of several factors. You’re rounding a corner
and hit a patch of ice, or loose gravel. You suddenly discover that a corner, or
curve, is sharper than you had anticipated. In either situation, as you try to
keep the vehicle on the road, the rear tires break loose and the vehicle whips
around.
The spin out is a very difficult skid to control. Keeping the vehicle on the
road, and pointed in the right direction, may be the best you can hope for.
Section 6 – RUNNING OFF THE ROAD:
There may be times, even in normal situation, when your vehicle goes off the
edge of the roadway, or some other vehicle forces you off the roadway edge. The
ability to recover from this is necessary, simply because you cannot predict
whether or not it will happen.
If your right side wheels drop off the pavement edge, onto a soft shoulder,
the appropriate response is to: (1) hold the steering wheel steady, (2) allow
the vehicle to slow down gradually, (very light and gradual braking might be
necessary, if obstacles are ahead), (3) when a very slow speed is reached, check
traffic and turn wheels sharply to the left, to bring the vehicle back onto the
pavement. A point to remember about different pavement edges is that if the edge
is smooth (no drop off), then return smoothly; if the edge is sharp (2 to 4 inch
drop), return sharply. Avoid slamming on the brakes or trying to steer back onto
the pavement at high speeds. Either of these actions can produce a dangerous
skid or rollover.
Section 7 – PROBLEMS THAT CAN ARISE WHEN NECESSARY TO USE EMERGENCY PROCEDURES:
With the use of emergency maneuvers come potential dangers that should be
considered. The quick braking technique increases your chances of being hit from
the rear. Since there is more of a chance of being hit from behind when using
this technique, you need to adjust how quickly you stop considering the danger
ahead if there is also a risk of collision with the vehicle behind you. Quick
braking also increases the possibility of skidding, especially on slippery
surfaces. If skidding does develop, remember to "get off the brakes".
The main danger involved in quick steering is that you may steer into the path
of other vehicles or into roadside hazards when you don’t have sufficient time
to make the vision checks and aren’t fully aware of what is to either side of
you. At high speeds, quick steering also increases the likelihood of a sideways
skid or even turning over.
Section 8 – SUMMARY
When you have responded to a situation, you must be prepared to change your
response if the situation changes. You must have alternatives available for you
to use, when you see that your response is not going to work. In other words
keep "working" at getting yourself out of the emergency as long as you
have a chance to control the car. This is needed since the use of a single,
emergency maneuvering technique may not allow you to avoid conflict.
The need for emergency procedures can normally be avoided by recognizing the
emergency at an earlier point, as it is developing. When these emergencies are
recognized, you can adjust to them before they call for an emergency procedure.