#51 Seasonal and Monthly Road Crashes

The summer holiday season invariably brings appeals from road authorities and safety advocates for road users to take extra care while travelling. The tragic loss of life and the serious injuries seen during this period attracts media attention and requests for drivers to appropriately manage risks such as speed, fatigue, impairment, and other factors often associated with rural crashes. This week, we look objectively at trends in serious transport-related injuries by month and season to offer a statistical context for the prevailing narrative.

Statistics sourced from the Australian Government Institute of Health and Welfare show national trends by month for the recent 5-year average transport-related deaths and hospitalisations. Figure 1 shows the number of people killed or seriously injured (KSI) combined for the 5 years up to 2021 and 2022, respectively. This shows that, overall, deaths and injuries combined tend to be fewer in the winter months and, notably, February, and most frequent in the months of October (5,759), December (5,726) and March (5,692).

However, looking closer at the trends for fatalities versus serious injuries reveals some interesting differences, as shown in Figure 2. While the highest proportion (%) of injury cases by month was seen in October, relatively fewer fatalities occurred in that month (and also September). December accounted for the highest proportion (9.1%) of fatalities by month, suggesting a higher fatal crash rate per head of population in the early part of the summer holiday season. Compared with December, numbers decline somewhat in January for both fatalities and injuries, but are still higher than monthly averages across the 5 years of data (noting that relatively low fatality numbers lead to greater fluctuation and lower statistical reliability).

Earlier research by the Centre for Automotive Safety Research (CASR) examined monthly trends for South Australia, looking at a range of factors including rural versus urban differences[1]. This research found that, from 1982-2013, while injury crash rates declined in urban areas in December and January, they increased significantly for the same period in rural areas, suggesting an association with increased rural travel in the summer holiday period. Overall, the national trends and other research provide justification for targeted road safety campaigns in the summer holiday season.

[1] Kloeden, C. & Hutchinson, T. (2015).  Variations in road injury crash numbers in South Australia by time of year (CASR128). University of Adelaide.