The Crash Study: An epidemiological approach to the analysis of motorcycle crashes in Tasmania 2012-2016

This report describes an in-depth study of transport-related motorcycle crashes reported to police in Tasmania over the period 2013-2016. The aim of the study was to identify trends and patterns in motorcycle crashes and the factors that contributed to those crashes. The objective was to improve understanding of the factors contributing to motorcycle crashes to inform crash countermeasures within a Safe System approach. The study framework analysed single and multivehicle crashes separately by crash type and key vehicle status based on the DCA (Definitions for Classifying Accident) system. The role of other contributing factors was then introduced including demographics, behaviour, road environment and weather conditions. The analysis included 1,479 crashes which were associated with 1,228 motorcycle riders and pillion passenger casualties. They included 34 fatally injured, 307 hospitalised with serious injuries and 685 treated in hospital but not admitted. Tasmanian motorcycle crash rates, particularly for young riders, were increasing each year while declining elsewhere. Riders aged 16-25 years were substantially over-represented in crashes, including over half of all riders who crashed on curves. They had over three times the crash rate of riders aged 26-39 and six times the rate of those aged over 40. The human factors identified by police as contributing to all crashes included inexperience (22%) and inattention (15%), excess speed (11%) and alcohol (4.1%). Fatigue was noted in only 2 cases but may have accounted for some of the inexperience and inattention noted. Higher proportions of fatalities and seriously injured were associated with human factors including respectively: inexperience (29%, 19%), inattention (15%, 16%), excess speed (29%,19%) drugs (21%, 9.8%) and alcohol (5.9%, 8.8%). Twelve crash sub-codes were found to account for 67% of all motorcycle rider and pillion casualties, including 71% of fatalities and 72% of serious injuries. The most injurious crash sub-code was Head-on (not overtaking) which accounted for 24% of fatalities and 9% of seriously injured. Three sub-codes, all relating to single vehicle crashes on curves, accounted for 18% of fatalities and 26% seriously injured. The majority of head on (not overtaking) crashes also occurred on curves (79%) with the key vehicle almost equally apportioned to the other driver (53%) and motorcyclist (47%). Rear end crashes accounted for 21% of all multivehicle crashes and the motorcycle was the key vehicle in 74%. Crashes on curves accounted for over half (52%) of all single vehicle crashes. Road surface defects were present at 15% of all crashes but 24% of single vehicle crashes. Loose gravel on a sealed surface was a factor for 10% of all casualties including 11% of those seriously injured. The study identified four crash types as a priority for attention: crashes on curves, head-on (not overtaking), rear end and intersection crashes. Countermeasures are suggested that may reduce the prevalence and severity of these types of crashes and the substantial proportion of casualties they represent. The analysis confirms the importance of examining single vehicle and multivehicle motorcycle crashes separately, in order to identify contributing factors more accurately. The results also demonstrate the relevance of pre-crash events to accurately capturing the factors leading to motorcycle crashes. The review of current coding practices found that using the last movement before impact as the sole basis for coding, is less appropriate to one-track (motorcycles) than for two track vehicles for understanding crash causes. It is accordingly recommended that coding practices be revised to enable precipitating events prior to the first impact, be incorporated into crash coding practices, particularly for single track vehicles. However, the inaccurate coding of almost half of the crashes, suggests a lack of appreciation of the importance and value of incorporating all precipitating factors into crash codes. This indicates an urgent need for training and quality control monitoring of crash coding practices. The findings of this report also underline the importance of taking a safe system approach to motorcycle crash investigations. A key recommendation is that motorcycles be adopted as the criteria vehicle in road infrastructure design and maintenance protocols due to their unique vulnerability to road conditions. Other countermeasures proposed include establishing centralized mapping and protocols for motorcycle crash investigations, to identify high risk roads for special measures such as head-on avoidance space on curves.