Towards linking climate and weather phenomena to road safety outcomes part 2 of 3: Longer-term influences of climate drivers

This paper is Part 2 of a three-part series illustrating how climate phenomena and weather metrics vary within a year and between years that can effect road safety. Part 1 identified the breadth of weather factors collectively contributing to crash risk and consolidated relevant research. The key climate drivers for Victoria produce complex interactions forming short-term and long-term weather patterns influencing crash occurrence and their spatial and temporal distribution across the state. The study found that the Southern Annular Mode (SAM) with its roughly 14-day cycle has the most significant influence on Victorian casualty crashes (also cyclic). A Chi-Square Goodness-of-Fit Test showed a statistically significant association (at the 0.05 significance level) between casualty crash numbers and each of the climate drivers. For fatal crashes, however, there was no statistically significant association, likely due to low numbers and randomness. Whilst this paper focuses on Victoria, other jurisdictions can use the approach presented using their local context of climate, latitude, and geography to identify patterns and influences on crashes. Understanding climate influences on crash occurrence within and between years assists strategy development for improving road safety and reaching the target of zero deaths.