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Drink driving offenders are usually detected by their
erratic driving behaviour, committing traffic offences, through being
involved in a crash, or in Random Breath Testing Initiatives.
The presence of alcohol in the bloodstream of a driver
or rider reduces driving skills and affects judgment and risk-taking
behaviour. More than a quarter of all drivers and motorcycle riders
killed in the Adelaide metropolitan area had
Blood Alcohol Concentrations (BACs) above the legal limit of 0.05.
In rural areas, 29% of drivers and riders killed had illegal
BAC levels.
On average, 22 male and 4 female drivers or riders with
a BAC level 0.05 or above are killed in fatal crashes each year.
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The most at risk group are 16-30 year old males. The 21 to 25 year age group
has the greatest number of drink drivers or riders killed.
Overall, 85% of the drink drivers or riders killed are male.
How can we stop drink driving?
Random breath testing (RBT) is one strategy used by the South Australia Police to reduce
and prevent road crashes and to make our roads safer.
Changes in legislation now enable mobile police units to conduct RBT at certain
times of the day or year such as at major holiday periods
During 2000, South Australia Police tested 537 928 drivers across South Australia (313
748 in metropolitan Adelaide and 224 180 in rural South Australia).
Of these drivers:
- 1703 in the metropolitan area
- 585 in rural areas
had a blood alcohol concentration (BAC) at or above 0.05.
The police conduct extensive RBT operations where recreational activity may
lead to increased levels of drinking and there is a higher crash risk. All
police vehicles are equipped to perform RBT operations and do so regularly.
A BAC test is also required for anyone aged 14 years or over who is injured
in a road crash, whether or not he or she was driving the vehicle at the time
of the crash.
Police can also conduct a breath test on a driver if he or she is involved
in a crash, commits a traffic offence, or appears to be driving under the
influence of drugs or alcohol.
Alcohol and crash risk
Blood alcohol concentration (BAC) is the amount of alcohol present in the body,
measured in grams of alcohol per 100 millilitres of blood. Studies have shown
that, as a driver’s blood alcohol level increases, so does the chance
of being involved in a crash.
Above zero, every increase of 0.05 in BAC doubles the risk of being involved
in a casualty crash — the higher the blood alcohol level, the more rapidly
that risk increases.
Drink driving offences
In South Australia, it is illegal to drive a vehicle or put a vehicle in motion
while impaired by alcohol or other drugs.
The Prescribed Concentration of Alcohol (PCA) is the level of blood alcohol
concentration at or above which it is illegal to operate a road vehicle. The
PCA for licensed drivers or “qualified passengers” accompanying
learner drivers is 0.05.
For learners, P-plate drivers, and drivers of transport vehicles such as
buses and trucks, the limit is ZERO.
However, even if you have not exceeded the legal BAC limit, you can still
be charged with a DUI (driving under the influence) offence if it is clear
that you are unable to control a vehicle because of the effects of alcohol
or any other drug.
Standard drinks
A breathalyser or a blood test is the only means of measuring your BAC.
A crude approach is to monitor the alcohol you consume in terms of “standard
drinks” which contain 10 millilitres of alcohol per serving.
Licensed premises serve measured quantities of alcohol in standard glasses
because they are selling it. Packaged beverages are labelled with the number
of standard drinks they contain. At home or at parties, you’re likely
to use non-standard glasses or top up your drink which makes it difficult
to monitor your consumption.
People absorb alcohol into their bloodstream at different rates. Body size
and general health affect the rate and a woman will nearly always have a higher
BAC than a man who drinks the same amount of alcohol.
The rate at which you absorb alcohol can also vary from day to day and will
be influenced by the rate at which you drink and any food you eat.
In South Australia, one standard drink is:
- A pint (425 ml) of light beer (2.7% alcohol)
- A schooner (285 ml) of “heavy” beer (4.9%)
- A small glass* (100 m) of wine (13%)
- A liqueur glass (60 m) of fortified wine (eg, port)
- A nip or shot (30 ml) of spirits
*Note that a normal restaurant glass full of wine could contain nearly two
standard drinks
Physiology - Safety Science
Alcohol affects us when it enters our bloodstream and is carried to our brain
and other organs. Most of the alcohol is absorbed through our small intestines.
When alcohol reaches our brains there are a number of immediate effects starting
with reduced inhibitions, judgment and control. As BAC rises, perception,
coordination, memory and comprehension become impaired. Dizziness and confusion
follow. At very high levels, the person becomes unconscious and could even
die from respiratory arrest.
Tiny amounts of alcohol leave the body through expiration (breathing out),
perspiration, and urination. But the only way that significant amounts of
alcohol are removed from the bloodstream is when it is metabolised in the
liver.
It takes a healthy liver about one hour to process the equivalent of one
standard drink. There’s nothing you can do to speed up this process
— hot coffee and cold showers might wake you up but they have no impact
on BAC.
As blood circulates through the lungs, some alcohol passes through the membranes
and into the air where it is exhaled with the breath. The proportion of alcohol
in the air is directly related to the concentration of alcohol in the blood.
The ratio, called the partition ratio, is about 2100:1 — the quantity
of alcohol in 2100 millilitres or just over two litres of exhaled air will
be the same as in one millilitre of blood. This enables breath analysis devices
— breathalysers — to be calibrated to give a BAC reading.
Pedestrians and cyclists
Attention tends to be focused on people who drink and then get behind the wheel
of a car. They certainly cause the most harm to themselves and others. But pedestrians
represent about 15% of the road toll, and nearly one-third of them were found
to have BACs greater than 0.05.
Drinking and cycling can be even more dangerous. Researchers in the USA have
shown that a single drink increases the risk of death or serious injury by
five times. Cycling requires greater psychomotor skill and physical coordination
than driving a car. Drunk cyclists were also less likely to wear a safety
helmet.
Some people who have lost their licence switch to cycling as a means of transport.
If they continue to drink and use the roads, they could be putting themselves
at even greater risk. Even walking while affected by alcohol is a dangerous
option.
A disturbing trend
Over the last 21 years, the incidence of drink driving has fallen significantly.
The percentage of drivers or riders with a BAC greater than 0.05 who were killed
on the roads reached an all-time low of 22% in 1988.
However, since then, there has been a steady increase to 32% in 2002 and
20% of all drivers or riders seriously injured also had BACs over 0.05.
Other Important Information
For more information, visit the
Department
of Transport and Urban Planning website.
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