80
Behavior at each BAC level may differ somewhat with each
individual. ALL people at the .10 percent level are definitely
too impaired to drive safely.
Research has proven that
driving skills, good judgment and vision are greatly
impaired at BAC levels as low as .03 and .04 percent,
especially for young drinkers. The above table, named
Alcohol’s Effects on Driving Ability, describes different levels
of intoxication and degree of behavior impairment at each
level.
Alcohol’s Effects on Driving Ability
Driving involves multiple tasks, and the demands can change
continually. To drive safely, you must maintain alertness, make
decisions based on ever-changing information present in the
environment and execute maneuvers based on these decisions.
Drinking alcohol impairs a wide range of skills necessary for
carrying out these tasks. Fatal injuries, resulting from alcohol-
related traffic crashes, represent a tremendous loss of human
life.
The plain and simple fact is that you cannot drive safely when
you are impaired by alcohol. The two abilities most important
to the driving task are judgment and vision, both of which are
affected by small amounts of alcohol. Your ability to judge
speed, time and distance are altered after only one drink. Each
extra drink greatly affects your driving ability. In addition,
your reaction time and coordination begin to deteriorate, while
your alertness and concentration fade. All of this adds up to a
deadly combination.
Judgment: Ability to Think Clearly and Make Quick
Decisions
Good judgment decreases with the use of alcohol. The
concern for physical well being also lessens. People under the
influence of alcohol take unnecessary and dangerous risks.
Examples are driving too fast, passing cars without enough
clear distance and speeding around curves. Showing off is
another example of impaired judgment.
Vision: Ability to See Clearly Straight Ahead, to the Side
and at Night
Alcohol decreases clearness of vision. It reduces the ability to
see clearly at night by more than half. Glare vision is poor
because of relaxed eye muscles. Glare recovery is also slowed
by alcohol. Side vision is reduced by about 30 percent at .05
percent BAC. Judging depth or distance is affected because
alcohol causes each eye to get a slightly different picture.
These vision impairments greatly increase the chances of a
head-on or rear-end collision. Eye muscles are relaxed by
alcohol and cannot focus properly. Because the eyes provide
almost 90 percent of the information used in driving, any
restriction in vision can cause disastrous results.
Reaction Time and Coordination:
This is the ability to react quickly and safely to an
emergency or hazardous situation—being able to keep
eyes, hands and feet working together.
Reaction and coordination are impaired by alcohol
consumption as low as .02 percent BAC. It takes longer to
BAC of Drinks Risk of Automobile Crash Comment
.01-
u
1 drink within Rises for young adults and others Stiff penalties for BAC as low as .02 if
.03% 15 min. with low tolerance for alcohol driver under age 21
.04-
u
2 drinks within Definite for anyone with Most people feel high and have some loss
.07% 1/2 hour low tolerance levels of judgment. You may get louder and have
some loss of small muscle control, like
focusing your eyes.
.08%-above
LEGAL INTOXICATION* — Judgment and reasoning powers are severely
hampered; cannot do common simple acts.
Definitely unsafe to drive.
.10-
u
4 drinks within Judgement loss increases. Many people claim they’re not
.12% 2 hours Increases 7 times the normal rate
affected anymore, as if they would drink themselves sober
when they are actually being affected more.
.13-
u
5-7 drinks 25 times the normal rate You have far less muscle control than nor-
.15% within 3 hours
mal and feel happy, even though stumbling
and acting foolishly.
.16-
u
8-12 drinks 50 times the normal rate You are confused and need help doing
.25% within 4 hours
things, even standing up. Alcohol-related
highway fatalities sharply increase.
Alcohol’s Effects on Driving Ability
*Lower levels are set for younger drivers, commercial drivers, and subsequent offenses, as discussed later in this chapter.