no72 2008
Had a Little Bit to Drink - Can I Drive?

  Among the various measures undertaken to fight drunk driving, tightening of regulations has shown
a particularly significant effect. However, in addition to applying heavier penalties to offenders, it is also necessary to provide drivers with attention-grabbing information to help them think on their own about the dangers of drunk driving.
  Drunk driving can be eradicated only when drivers themselves fully understand how alcohol affects the
ability to drive: how it influences the perception of danger and dynamic visual acuity, and how it diminishes the capability to manipulate the steering wheel, accelerator, etc., based on actual statistics, to make them think about how dangerous drunk driving is, and how it can be prevented.
  This issue of ITARDA INFORMATION presents various aspects of drinking and driving, including the correlation between alcohol intake and blood alcohol concentration, and the effect of alcohol on the ability to drive.
Section 1."Drunk Driving" and "Driving under the Influence of Alcohol"

Section 2.Calculating Alcohol Concentration

Section 3.Effect of Alcohol on Driving


  Driving a car is a constant repetition of "perception", "judgment", and "operation".
When a driver has been drinking, a likely scenario would be something like this: the driver is slow to perceive danger, notices a dangerous situation too late, and acts in a flurry, resulting in excess manipulation that causes an accident. Some test subjects showed considerably high breath alcohol concentration even four hours after drinking, and others operated the steering wheel excessively even when they did not drink much.
How much alcohol is safe to drink? How many hours after drinking should I wait before getting behind the steering wheel? Is it safe to drive if I had some sleep? Do not answer these questions based on your own self-serving reasoning, or on a smattering of knowledge picked up somewhere.
The correct answer to the above questions is: Never drive after having a drink, and if you must drive, do not touch any alcohol!

Amount of water in the body differs significantly depending on gender, age, and constitutional makeup.
Some theorize that it is 58%, and others, between 60 and 70%. Here, the largest estimation, 70%, is adopted. Blood alcohol concentration comes out the lowest based on this body water ratio.

Blood alcohol concentration is generally obtained by multiplying the breath alcohol concentration by 2,000.
2 × breath alcohol concentration (mg/l) = blood alcohol concentration (mg/ml)

The two values obtained by deducting loss of alcohol (0.7-0.8) from the theoretical blood alcohol concentration is the concentration immediately after drinking. Since some alcohol remains unabsorbed right after drinking, the actual blood alcohol concentration comes out lower than the calculated values.
  Blood alcohol concentration peaks out 20 to 40 minutes after drinking, when all alcohol is absorbed by the body.

Maximum and minimum values were also obtained for the rate of alcohol decrease. The former is calculated by deducting the minimum decrease value from the blood alcohol concentration immediately after drinking, and the latter, by deducting the maximum decrease value from the same.

The two tests were conducted in different years, using different simulators, on a different set of test subjects. Test A was undertaken on 24 males aged 25 to 57, and Test B on 18 males aged 25 to 51.

Breath alcohol concentration in the legend is the target peak breath alcohol concentration 20 minutes after consuming alcohol. Each subject was directed to consume a certain amount of alcohol to obtain the target value. Individual differences, however, were significant and some subjects drifted considerably from the target value. The target values are therefore only a guide showing whether the amount of consumed alcohol was large or small.

Average reaction interval also showed a significant difference at the 5% level when sober and when alcohol is consumed in the t-test as well.

Institute for Traffic Accident Research and Data Analysis (ITARDA)