Alcohol and its effect on driving

by | Apr 13, 2018 | Alcohol, Blood Alcohol Content (BAC), Drink and Drive, DUI, Impaired Driving

How Alcohol Impairs Driving?


Alcohol is a major risk to driving. When driving on the road, you need to concentrate by keeping your eyes on the road, reacting to changing road conditions and controlling different aspects of your vehicle. By drinking alcohol and driving, you slow down your ability to control the steering wheel, the brakes and gas pedal. The effect of alcohol on driving is detrimental.

Reaction Time and Physical Impacts

There has been abundance of research that shows Alcohol affects the brain and how it reduces your reaction time. Studies have shown that reaction time increases from 1.5 seconds to 3 seconds when blood alcohol content (BAC) reaches 0.08. If it normally takes you 1.5 seconds to react to something, you will be taking 3 seconds to react. If you’re driving 60mph, you will travel 130 feet in 1.5 seconds so that means if you drink and drive, you will be stopping 130 feet later than if you are sober. The brain is part of the Central Nervous System (CNS) and it’s made up of billions of neurons. The neurons forms a network that carries information to the neck and arms, trunk, legs, skeletal muscles, and internal organs. Muscle coordination decreases while intoxicated and the driver is very likely to respond incorrectly to their environment. This means if you see a change in signal, you may not respond properly by braking and instead accelerate instead. You may also not respond at all because you are not concentrated at the task at hand. This is extremely dangerous to both the driver, passenger and other drivers and pedestrians on the road. A driver will have trouble doing basic tasks to drive a car safely if they are impaired by alcohol. A driver needs to multi-task by scanning the road, adjusting their speed and reacting to other vehicles and pedestrians. All of this will be affected by drinking. Research have shown that behaviors such as steering and braking will be affected with BAC starting at 0.05. Everyday, 28 people in the US die from motor vehicle crashes that’s alcohol related (1 death every 51 minutes).

Effects at different BAC levels:

Blood Alcohol Concentration (BAC)*Typical EffectsPredictable Effects on Driving
.02% About 2 alcoholic drinks**
  • Some loss of judgement
  • Relaxation
  • Slight body warmth
  • Altered mood
  • Decline in visual functions (rapid tracking of a moving target)
  • Decline in ability to perform two tasks at the same time (divided attention)
.05% About 3 alcoholic drinks**
  • Exaggerated behavior
  • May have loss of small-muscle control (e.g., focusing your eyes)
  • Impaired judgment
  • Usually good feeling
  • Lowered alertness
  • Release of inhibition
  • Reduced coordination
  • Reduced ability to track moving objects
  • Difficulty steering
  • Reduced response to emergency driving situations
.08% About 4 alcoholic drinks**
  • Muscle coordination becomes poor (e.g., balance, speech, vision, reaction time, and hearing)
  • Harder to detect danger
  • Judgment, self-control, reasoning, and memory are impaired
  • Concentration
  • Short-term memory loss
  • Speed control
  • Reduced information processing capability (e.g., signal detection, visual search)
  • Impaired perception
.10% About 5 alcoholic drinks**
  • Clear deterioration of reaction time and control
  • Slurred speech, poor coordination, and slowed thinking
  • Reduced ability to maintain lane position and brake appropriately
.15% About 7 alcoholic drinks**
  • Far less muscle control than normal
  • Vomiting may occur (unless this level is reached slowly or a person has developed a tolerance
  • for alcohol)
  • Major loss of balance
  • Substantial impairment in vehicle control, attention to driving task, and in necessary visual and auditory information processing

Making Bad Decisions

Because the prefrontal cortex is not mature, alcohol can harm a teen’s ability to reason and make choices. Teens may do something simply because it is fun or feels good and they can take risks they would not usually take. Because connections between the prefrontal cortex and the ventral striatum are still maturing, alcohol can affect those connections. As a result, teens may do impulsive things, such as drinking and driving or having unprotected sex. Both of these activities can have negative consequences. This will be very dangerous because they may not even know they are impaired and will continue to drive thinking everything is fine. When driving impaired, the driver may take reckless decisions they may not normally make such as driving too quickly or making frequent lane changes. As you can see in the table above, BAC of 0.02 can affect a person’s decision-making abilities. Don’t drink and drive! Check out 101 DUI Tips to avoid getting in trouble and losing your license.

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