Drink and Drug driving

Driving under the influence of drugs and in particular alcohol is one of the biggest killers on Tasmanian roads. Every year, at least one in four fatalities and one in eight serious injuries can be linked to drink driving. Between 2004 and 2008 inclusive, alcohol and other drugs were a contributing factor to 134 fatalities.

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.

What is 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 drink with any alcohol in their system, it is 0.00. Other restrictions apply for various licence holders with further details available at www.transport.tas.gov.au.

How does alcohol affect 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
  • ability to see or locate moving lights correctly: diminished
  • ability to judge distances: diminished
  • tendency to take risks: increased
  • ability to respond to more than one thing happening at once: diminished.

Double

0.05 - 0.08
  • ability to judge distances: reduced further
  • sensitivity to red lights: impaired
  • reactions: slower
  • concentration span: much shorter.

Five times greater

0.08 - 0.12
  • euphoria sets in
  • overestimation of ability leads to reckless and unsafe driving
  • peripheral vision: impaired (often results in crashes due to hitting passing vehicles and obstacles).

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.

Standard Drinks and Blood Alcohol

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.

Everyone is different and some people need to drink less than the standard hourly recommendations to maintain a BAC level below the legal limit.

Remember the ONLY thing that will lower your BAC is time.

All the above factors will affect the level of your BAC but none will actually lower it.

When monitoring your alcohol intake, it is important that you are monitoring standard units of alcohol, not the number of actual drinks consumed. Alcoholic drinks served in bars and clubs are often much more than a standard unit. For example a 375ml bottle of beer can range from 1.4 to 1.8 standard units, a glass of wine is generally 150ml, which is 1.5 standard units. For more information click here.

How do drugs affect driving performance?

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.