Drink and drug driving
Driving under the influence of drugs and in particular alcohol is one of the biggest killers on Tasmanian roads. At least one in four fatalities and one in eight serious injuries can be linked to drink driving. Alcohol and other drugs were a contributing factor in 185 of the 433 fatalities in the 10 years to 31 December 2013.
Six percent of Tasmanians are aged between 17 and 25 but are 28 percent of serious casualties. This age group has a six times greater chance of being a serious road crash casualty – seriously injured or killed – than the rest of the population. Of those casualties, going too fast for the conditions and/or circumstances was a factor in 52 percent, alcohol 37 percent and going over the speed limit 21 percent.
Alcohol and other drugs, whether medicinal or illicit, can decrease your:
- mental alertness, vigilance and concentration
- physical coordination, and
- ability to react quickly and appropriately to what is happening on the road.
Alcohol, alone or in combination with other drugs, does not mix with driving. Many medicines carry labels warning that they may cause drowsiness and advising you not to drive. Although illegal drugs do not carry these warnings they are equally as dangerous.
Blood or breath alcohol concentration
Blood or Breath Alcohol Concentration (BAC) is a measurement of the amount of alcohol in the body. BAC measures milligrams of alcohol per 100 millilitres of blood.
The legal BAC limit for a full licence holder is 0.05, which is 50 milligrams of alcohol per 100 millilitres of blood. For a learner or provisional driver who is unable to drive with any alcohol in their system, it is 0.00. There are other restrictions for various licence holders and for more information about licences see here.
How alcohol affects driving performance
Driving is not a simple task. It requires complex decision making and total concentration at all times. Alcohol affects your ability to be in control of your own actions.
The following table shows the effect of different levels of blood alcohol and your increased crash risk when compared with a driver with a BAC of 0.00.
|BAC||Effect on your driving||Crash risk|
|0.02 – 0.05||
|0.05 – 0.08||
||Five times greater|
|0.08 – 0.12||
||Ten times greater|
If you are planning to drink, then plan not to drive. Plan ahead and arrange overnight accommodation or alternative transport home. You could:
- share a taxi with friends
- catch public transport
- ride with a driver who hasn’t been drinking or taking drugs or
- arrange for a friend or relative to give you a lift.
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Standard drinks and blood alcohol content
Many different factors affect BAC, so you are unlikely to be able to judge your own BAC accurately. Factors that affect your BAC include:
- the amount of alcohol consumed
- the period of time over which alcohol is consumed
- your body weight
- whether or not you have eaten
- how much water you have consumed between drinks
- your fitness level and general health
- the health of your liver.
You need to be aware of standard drinks to estimate your blood alcohol level (BAC). The chart below shows what one stadard drink is for each type of alcohol.
A standard drink has about 10 grams of alcohol. Hotels and restaurants do not always serve alcohol in standard drink size glasses. Wine is normally sold in 140ml or 200ml glasses. One 200ml glass of wine is about two standard drinks. Glasses used at home are unlikely to be standard drink size.
The labels on alcoholic drink bottles and cans show the number of standard drinks they are.
The amount of standard drinks in average alcohol serves
A stubby of full strength beer is 1.4 standard drinks. An average restaurant serving of wine is 1.5 standard drinks. a 30ml nip of 40 percent alcohol volume is one standard drink. For more information click here.
One standard drink an hour will raise your BAC by between 0.01 percent and 0.03 g%. Your BAC is more likely to rise at a greater rate if you:
- Are female
- Have a low body weight
- Are a fast drinker
- Have not eaten recently
- Are drinking highly carbonated drinks such as champagne.
The liver takes about one hour to break down one standard alcoholic drink per hour (the average rate is 7.5 grams per hour but this can vary between four and 12 grams per hour for different people). A liver damaged, for example, by hepatitis, will break down alcohol more slowly.
To prevent your BAC rising further don’t drink more than one standard drink per hour.
The only reliable method of reducing your BAC is to wait out the time for the alcohol to be metabolised.
Cold showers, black coffee, fresh air, exercise, vomiting and other home remedies may help you feel more alert but will not reduce your BAC.
Driving a motor vehicle safely requires good coordination and mental alertness. Many prescription and non-prescription medicines affect your ability to drive safely.
Combining different medications may have an even greater effect on your ability to drive safely.
Some negative effects of prescription and over the counter medications include drowsiness, blurred vision, poor concentration, slower reaction times and feeling aggressive.
Serious penalties and fines apply for drug related offences including driving while affected by prescription medications.
How illegal drugs effect driving
Research shows that a driver who has recently consumed cannabis or an amphetamine-based substance is at the same risk of having a crash as a driver with a BAC above 0.05.
THC (an active component of cannabis) impairs mental function and reduces attention and concentration on driving. THC significantly increases crash risk and affects driving even when there are no outward signs of impairment.
Methamphetamines (speed), MDMA (ecstasy), cocaine, heroin, ketamine and other drugs along with some prescription medicines, increase risk taking and aggression. Some drivers use drugs to temporarily allow them to continue to drive even though they are too tired to do so safely.