The national enforcement movement for "Drive Sober or Get Pulled Over" is August 18th-September 6th. Police records show that about half of all motor vehicle-related fatalities involve alcohol, whether it’s the driver, a passenger, or someone else, like a pedestrian. Most of these fatalities were caused by a drinking driver. Let’s take a look at some relevant information about drinking and driving.
What is alcohol?
Alcohol is an odorless, colorless depressant, which means it slows down activity in the brain and the central nervous system. This affects motor coordination. When people are intoxicated, they may have difficulty walking or moving, and their ability to speak may be so impaired that they slur their words.
Alcohol is primarily consumed in the form of beer, wine, or distilled spirits. The amount of alcohol in popular beverage varies, but in general:
- Beer is around 3.2% to 5% alcohol.
- Wine coolers are around 4% to 8% alcohol.
- Malt liquor is around 5% to 10% alcohol.
- Wine is around 10% to 16% alcohol.
- Distilled spirits are around 39% to 50% alcohol.
The amount of alcohol in a drink depends on what you’re drinking. Most alcoholic beverages will tell you the alcoholic proof (i.e., the percentage of alcohol times two) on the label. So, you’ll know that 80 proof liquor contains 40% alcohol.
Does alcohol make it harder to drive?
Yes. The following are greatly affected by alcohol consumption:
- Judgment and reasoning
- Awareness and alertness
- Vision
- Physical condition
- Coordination
- Reaction time
Drivers often have limited knowledge of the impairing effects of alcohol, or they misinterpret the clues of impairment. At higher BACs, their inhibitions become reduced, and they underestimate the alcohol-crash risk, which leads to risk taking.
Even at low BACs, the ability to concentrate on two activities simultaneously is affected. For instance, a driver may not be able to stay within their lane while also adjusting the radio.
Alcohol also diminishes your ability to identify hazards and respond to them. Reaction times are slowed greatly, even if the correct decision is made. If you are under the influence of alcohol, you may be unable to handle an emergency situation that requires quick decision making and reflexes.
The ability to make rapid and correct judgments while driving is critical. Even low levels of BAC (as low as 0.02%) have been shown to adversely affect the judgment of experienced bus drivers trying to negotiate a bus through a narrow passage. This degradation of judgment is greater in younger drivers.
Several key misperceptions develop as a person drinks alcohol. First, intoxicated drivers overestimate their ability to drive. Second, they downplay or minimize the likelihood that something bad will happen. Finally, they lose the ability to estimate how impaired they are. These misperceptions lead to greater risk taking and poor decision making.
Distance, depth, and speed perception are also affected by the consumption of alcohol. This means that an impaired driver may not be able to tell how fast they are driving or how far away the stop sign up ahead is. Their ability to make decisions is severely compromised when they’re not perceiving what’s happening around them correctly.
Awareness also is reduced in drivers who have been drinking. Alcohol-impaired drivers tend to stare rather than scan. This can significantly impair their awareness of developing traffic situations and surrounding vehicles.
Impaired drivers also forget how to perform certain tasks, such as turning on or dimming their headlights. They often forget to buckle their seat belts, increasing their risk of death in a crash.
Alcohol also diminishes a driver’s ability to distinguish objects, particularly if they are dimly lit. Considering that most people increase their alcohol consumption at night, this is not a good situation for impaired drivers. Degraded vision due to alcohol may be another reason for alcohol-related nighttime crashes.
What is BAC?
You’ve probably heard the term "BAC" used when talking about drinking drivers. Blood Alcohol Content (BAC) shows us how much alcohol is in someone’s bloodstream. The only way to accurately measure a person’s BAC is by administering a blood test, urine test, saliva test, or breath test. You can, however, roughly calculate your own BAC.
Drivers age 21 and older are considered intoxicated when their BAC is .08% in most states, though in Utah the limit is .05%. The limit varies for underage drivers based on their state’s Zero Tolerance laws.
BAC depends on a few factors, including what time you started drinking, how much you drank, and your weight. An average drink (e.g., 12 oz. of beer, 5 oz. of wine, or 1 oz. of distilled spirits) will produce a BAC of .020% in a 160-pound person, .030% in a 110-pound person, .015% in a 220-pound person, etc.
Once the alcohol is in your bloodstream, which takes about 15-45 minutes, all people, regardless of weight, will metabolize (i.e., burn up) from .015% to .020% of alcohol in about an hour (e.g., one drink for a 160-pound person). This amount tends to decrease with age, with middle aged people burning less alcohol per hour than younger people.
Most alcohol is metabolized by the liver, where an enzyme called alcohol dehydrogenase (ADH) breaks ethanol down into acetaldehyde. Acetaldehyde, in turn, is broken down by another enzyme into acetate, which then is excreted.
The rate at which alcohol is metabolized and eliminated from the body is critical to understanding how long a person can expect to be affected by drinking. The elimination of alcohol from the body can be affected by two main factors: rate of consumption and tolerance.
How can you tell if a driver has been drinking?
It’s pretty easy for law enforcement to guess when a driver may have a BAC of .08% or higher. Drinking drivers tend to turn with a wide radius and straddle the center of the road or lane markings. They may almost strike other objects or vehicles. Weaving, swerving, drifting, braking erratically, and following too closely are also warning signs. Other indicators include:
- Driving on surfaces other than the designated highway
- Driving more than 10 mph under the speed limit, even though conditions don’t dictate it
- Driving into opposing traffic signals
- Abrupt or illegal turns
- Rapid acceleration or deceleration
- Driving with the headlights off
- Excessive speeding
- Keeping the windows down even in very cold weather
- Failure to use turn signals before turns or changing lanes
Police have better equipment than ever and actively look for drinking or impaired drivers.
We hope this helps you make smart driving decisions. It’s everyone’s responsibility look out for each other on the road, so do your part by driving sober!
Want to learn more about traffic safety? Taking an online defensive driving course or an insurance discount course is a great way to help prepare you for any type of driving situation! Click here to visit our website to see the online courses we offer in your state!