Alcohol, speed and driving

[3-000] Alcohol and road accidents

Drink driving is a factor in about 18 per cent of all fatal crashes in NSW. Seventy per cent of all fatal drink drive crashes occur in country NSW. The majority of drink drivers in fatal crashes are male (90 per cent) and one third of all drink drivers in fatal crashes are aged 17–24 years (despite making up only about one seventh of all licensed drivers). Thirty per cent of all fatal drink drive crashes occur between 9 pm and 3 am on Thursday, Friday and Saturday nights.

See: Transport for NSW, Road User Handbook.

[3-020] Increased risk with alcohol

A driver’s risk of being involved in a crash increases with the amount of alcohol in the blood stream. At .05 the risk of a crash for the average driver is about twice that of zero blood alcohol. The risk keeps getting higher as the blood alcohol level rises:

  • at .05 is double that at zero

  • at .08 it is about 7 times higher than at zero

  • at .15 it is 25 times higher than at zero.

On Thursday, Friday and Saturday nights about 50 per cent of crashes involve alcohol. Crashes involving alcohol are generally more serious.

[3-040] Measuring your blood alcohol concentrate (BAC)

Measuring your BAC is impossible without an Australian standards approved breath testing machine.

Guessing your BAC is inaccurate because:

  • alcohol concentration of the drink may vary from 2.5 per cent (light beer), 5 per cent (eg full strength beer) to over 40 per cent (eg, vodka, whisky)

  • beer may be served in schooners, middies, etc. Wine glasses vary from 100 to 280 mls

  • in many situations, drinks are topped up making it difficult to know how many standard drinks are consumed

  • many drinks come in non-standard sizes — eg, pre-mixed drinks in cans and bottles may contain more than one standard drink.

Factors such as your gender, size, weight, health and liver function will affect your BAC:

  • size and weight — a smaller person may have a higher BAC from the same amount of alcohol

  • liver function — an unhealthy liver processes alcohol more slowly

  • gender — a woman of the same height and weight as a man drinking the same amount may have higher BAC

  • consumption of food — lack of food in the stomach means faster absorption of alcohol into the blood stream. Eating after drinking will not reduce the BAC

  • general health condition and level of fitness can affect a person’s ability to process alcohol. A person’s BAC can be higher if they are not feeling well, or are tired or stressed

  • consumption of other drugs affects a person’s ability to process alcohol.

[3-060] How alcohol affects driving

  • brain function (alcohol being a depressant drug) so you can’t respond to situations, make decisions or react quickly

  • reduces ability to judge speed and distance

  • gives false confidence

  • makes it harder to do more than one task

  • makes you sleepy or fatigued.

  • affects your sense of balance and coordination.

[3-080] Staying under the limit guidelines no longer apply

The Road and Traffic Authority no longer suggests guidelines as to the number of standard drinks per hour because of the variations in alcohol content and factors that are referred to above that may affect the BAC.

[3-100] Speed and driving

Speeding was a factor in 43 per cent of all fatalities and approximately 17 per cent of all crashes. Twenty nine per cent of all speeding drivers and motor cycle riders involved in fatal crashes were males aged 17–25 years.