Characteristics of Fatal Road Traffic Crashes Associated with Alcohol and Illicit Substances in Queensland (2011-2015)

Psychoactive substances affect driver behaviour in different ways, some of which can increase the risk of traffic crashes. This study investigated coroners findings for fatal road traffic crashes in Queensland for crash factors and driver behaviours associated with and without the presence of alcohol or illicit drugs. A total of 701 coroners reports for the period of 2011 to 2015 were analysed revealing 306 fatal incidents involving the detection of either alcohol or target illegal drugs (e.g., methamphetamine, THC [cannabis], cocaine or MDMA). Alcohol was most often detected (223 cases; 72.9% of the drug and alcohol sample and 31.8% of the entire sample), and a majority of fatalities involving alcohol (n = 114, 51% of alcohol cases) were at high range BAC levels (> .150g/100ml). Of these, 37 (32.5% of high range and 16.6% of alcohol cases) were detected with illicit drugs. Single vehicle and multi-vehicle crashes were evenly represented, although males were overrepresented in all crash types. Alcohol and poly-drug consumption were more likely to be associated with single vehicle crashes (81.7% and 64.6% respectively), while detections of methamphetamines and THC in isolation without other substances were slightly overrepresented by multi-vehicle crashes (58.6% and 59.4% respectively). Single vehicle crashes usually involved speeding, loss of control and failure to negotiate a curve while multi-vehicle crashes were disproportionately represented by reckless driving and misjudging traffic conditions. Overall, an important theme to emerge was the contribution of illicit drugs and alcohol to the majority of single vehicle crashes, highlighting the increased risk of this type of crash for drivers who are positive with these substances.