4-6
Control of a Vehicle
You have three systems that make your vehicle go where
you want it to go. They are the brakes, the steering and
the accelerator. All three systems have to do their work
at the places where the tires meet the road.
Sometimes, as when you're driving on snow or ice, it's
easy to ask more of those control systems than the tires
and road can provide. That means you can lose control
of your vehicle. Also see ªTraction Assist Systemº in
the Index.
Braking
Braking action involves perception time and
reaction time.
First, you have to decide to push on the brake pedal.
That's perception time. Then you have to bring up
your foot and do it. That's reaction time.
Average reaction time is about 3/4 of a second. But
that's only an average. It might be less with one driver
and as long as two or three seconds or more with
another. Age, physical condition, alertness, coordination
and eyesight all play a part. So do alcohol, drugs and
frustration. But even in 3/4 of a second, a vehicle
moving at 60 mph (100 km/h) travels 66 feet (20 m).
That could be a lot of distance in an emergency, so
keeping enough space between your vehicle and others
is important.
And, of course, actual stopping distances vary greatly
with the surface of the road (whether it's pavement
or gravel); the condition of the road (wet, dry, icy);
tire tread; the condition of your brakes; the weight
of the vehicle and the amount of brake force applied.
4-15
Check your mirrors, glance over your shoulder and
start your left lane change signal before moving out
of the right lane to pass. When you are far enough
ahead of the passed vehicle to see its front in your
inside mirror, activate your right lane change signal
and move back into the right lane. (Remember that
if your right outside mirror is convex, the vehicle
you just passed may seem to be farther away
from you than it really is.)
Try not to pass more than one vehicle at a time
on two
-lane roads. Reconsider before passing the
next vehicle.
Don't overtake a slowly moving vehicle too rapidly.
Even though the brake lamps are not flashing, it may
be slowing down or starting to turn.
If you're being passed, make it easy for the following
driver to get ahead of you. Perhaps you can ease a
little to the right.
Loss of Control
Let's review what driving experts say about what happens
when the three control systems (brakes, steering and
acceleration) don't have enough friction where the tires
meet the road to do what the driver has asked.
In any emergency, don't give up. Keep trying to steer and
constantly seek an escape route or area of less danger.
Skidding
In a skid, a driver can lose control of the vehicle.
Defensive drivers avoid most skids by taking reasonable
care suited to existing conditions, and by not ªoverdrivingº
those conditions. But skids are always possible.
The three types of skids correspond to your vehicle's
three control systems. In the braking skid, your wheels
aren't rolling. In the steering or cornering skid, too
much speed or steering in a curve causes tires to slip
and lose cornering force. And in the acceleration skid,
too much throttle causes the driving wheels to spin.
A cornering skid and an acceleration skid are best
handled by easing your foot off the accelerator pedal.
A cornering skid is best handled by easing your foot
off the accelerator pedal. If you have the ªTraction
Assist System,º remember: It helps avoid only the
acceleration skid.
