Ferris, Jason

Mazerolle, Lorraine

University of Queensland eSpace

page4
Random Breath Testing: Impact on Alcohol Related Crashes
Project Update
Overview 
In 1962, the World Health Organisation released a seminal paper 
on road traffic accidents noting that “there is much evidence 
to indicate that alcohol consumption by a road user is a major 
factor in road traffic accident causation”.1 Yet, forty-years on, 
driving whilst under the influence of alcohol remains an ongoing 
and serious problem in motorised countries. 
Random Breath Testing (RBTs) as a mechanism to reduce alcohol-
related traffic accidents was introduced in Australia in 1976. 
Following the introduction there was a significant decline in 
alcohol-related traffic crashes (ARTC) with RBTs being attributed 
to an almost 50% reduction in the number of fatal accidents; and 
by extension the introduction of RBTs has resulted in a reduction 
in the social and economic impacts of alcohol-related crashes. 
Figure 1 highlights the year in which each state first conducted 
an RBT program and the estimated reduction on road fatalities 
associated with RBTs.  
The effectiveness of RBTs in reducing ARTC has principally 
resulted from deterring drivers from drink-driving for fear of 
being caught.  That is, the mechanisms of deterrence models, as 
describe by Ross Homel is to discourage motorists from engaging 
in acts of criminality – in this case driving under the influence of 
alcohol – of which RBTs are an effective deterrence model.2
The Emergence of Random Breath Testing in 
Australia
The abuse of alcohol is one of the most prominent causes of 
preventable illness, injury and fatality within Australia. Four 
1  L. G. Norman (1962). Road traffic accidents: Epidemiology, control and prevention. 
Geneva, Switzerland, World Health Organisation. P62
2  R. Homel (1988). ‘Random Breath Testing in Australia: A complex deterrent.’ Austral-
ian Drug and Alcohol Review 7(3): 231-241.
people are killed and 90 people are injured daily on Australian 
roads as a result of alcohol-related traffic accidents. The social 
and economic costs are staggering. In order to reduce alcohol-
related crashes and their related impact on individuals and 
society, significant resources have been allocated to develop 
appropriate strategies to reduce and deter drink-driving; one of 
these measures was the introduction of RBTs. 
RBTs: A ratio against licensed drivers
Currently in Australia no federal regulatory policy exists to 
set how many RBTs should be conducted annually.  Whilst 
Queensland police has an ‘in-house’ agreement for the annual 
number of RBTs to be conducted  (1 RBT:1  licensed driver), most 
other states and territories simply adopted Homel’s original 
suggestion of 1 RBT per 3 licensed drivers.3 Our research provides 
a preliminary analysis of alcohol related crash outcomes for two 
states – Queensland and Western Australia.
Data sources
Our research draws on three administrative data sources: the 
number of annual random breath tests conducted; the monthly 
number of ARTC - where blood alcohol concentration reaches or 
exceeds 0.05g/dL of alcohol in blood; and the annual number 
of licensed drivers (all supplied by jurisdictional police).  For 
Western Australia, administrative data from all three sources 
spans was available from January 2001 to December 2010 
(inclusive). Due to administrative restrictions, Queensland data 
for RBTs spanned January 2000 to December 2011, for ARTC July 
2004 to June 2009, and for number of licensed drivers, June 
2002 to December 2011.
Results
The primary finding of this research reveals different patterns of 
RBTs and ARTC exists between Queensland and Western Australia 
(see Figure 2). In Queensland (see Figure 2a), the average rate of 
RBTs has steadily increased to maintain the 1:1 RBT to licenced 
driver ratio. The average number of ARTC between 2004 and 
2008 remained relatively steady with an average of 150 crashes 
per month, before the number of ARTC slowly increased, with 
an average of 163 crashes per month between 2008 and 2009.  
In Western Australia, the monthly average of RBTs conducted 
decreased over the ten year period.  The average number of 
RBTs conducted in 2010 was almost half that of the number of 
RBTs conducted in 2001.  This highlights a notable shift from a 
deterrence-based to a targeted-based RBT initiative. Between 
2005 and 2009 the rate of RBTs decreased by one-third, yet 
drink-driving charges were on the rise. This data reflects a 
transition towards targeting resources to apprehend drink 
drivers. Notably, this approach contradicts the purpose of RBTs 
as a deterrent. And as other crash data shows, the steady rate of 
alcohol-related crashes averaging 77 per month between 2001 
and 2006, surged dramatically between 2006 and 2009 to an 
average of 100 ARTC per month.
3  R. Homel (1989). Crime on the Roads: Drinking and Driving. Alcohol and Crime 
Conference, Perth, Australian Institute of Criminology.
Figure 1: By state, year of first RBT and estimated impact of road 
fatalities
By Mr Jason Ferris and Prof. Lorraine Mazerolle
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(2a). Queensland (2b). Western Australia
While the absolute number of ARTC in Queensland is roughly 
twice that observed in Western Australia (see Figure 2 above), 
the total number of licensed drivers in Queensland is more than 
double that of Western Australia. We have adjusted for this 
difference by modelling the proportion of alcohol related traffic 
accidents relative to the number of monthly RBTs conducted 
(presented per 10,000 RBTs).
Figure 3 highlights a downward trend between the number of 
ARTC per 10,000 RBTs (y-axis) and the ratio of RBTs conducted 
against the annual number of licensed drivers (x-axis).  The 
nature of the data suggests that where the ratio of RBTs 
to licensed drivers is less than 1:1 (or 100%), the gain by 
improving the ratio of RBTs to licensed drivers on reducing 
ARTC is substantially greater compared 
to ratios that exceed 1:1. Our results 
suggest that increasing the ratio of 
RBTs to the number of licensed drivers 
from the Australian default of 1:3 to the 
Queensland standard of 1:1 could result 
in a reduction of 17 ARTC for every 
10,000 RBTs conducted.  While exceeding 
the Queensland ratio of 1:1 should 
result in fewer ARTC, the gain is not as 
substantial.  For example, increasing 
the Queensland ratio to 1.5:1 from 1:1, 
the reduction of ARTC per 10,000 RBTs 
would be approximately two.
The Need to Create a National 
RBT Minimum 
Our research demonstrates a strong link 
between the number of RBTs conducted 
annually and the number of alcohol-
related traffic accidents that occur where 
a driver’s BAC reached or exceeded 
0.05g/dL of alcohol in the blood. The 
effectiveness of RBTs lies in deterrence 
and a key component to deterrence is exposure.  Our research 
shows that as the rate of RBTs conducted increases, exposure 
to the presence of police increases. Consequently, the number 
of driver’s willing to risk being detected for drinking driving 
decreases, which in turn lowers the number of ARTC.
The comparison between Western Australia and Queensland 
showed that Queensland’s ARTC rate was almost half the rate 
of Western Australia while their RBT rate was, in some periods, 
over four times that of Western Australia. Moreover, if the 
commonplace RBT ratio of 1:2 in Western Australia doubles 
to a ratio of 1:1 RBTs to the number of licensed drivers, the 
expected number of ARTC per 10,000 RBTs should more than 
halve, from almost sixteen ARTC per month to seven. Using 
data from Western Australia as an example, these results give 
strong credence to the need to increase 
the number of RBTs conducted in most 
states and the Federal Government to 
introduce a national RBT minimum rate. 
Summary 
The introduction and use of RBTs in 
Australia has become an effective 
law enforcement initiative that has 
been embraced by the community as 
both a general and specific deterrent 
measure against drinking and driving. 
This initiative has been adopted by 
law enforcement agencies all over 
the world, and has been in practice 
within Australia for over 35 years. As a 
deterrent measure, its aim is to increase 
an individual’s level of risk towards the 
ramifications of driving while under the 
influence of alcohol as it pertains to 
apprehension or serious injury or death 
from an ARTC. 
Figure 2: Absolute number of alcohol related traffic crashes and RBTs by state
Figure 3: Number of alcohol-related accidents per 10,000 RBTs relative to the percentage of 
RBTs to licensed drivers


Random breath testing: impact on alcohol related crashes

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Random breath testing: impact on alcohol related crashes

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