Research Papers (2009 – 2013)

Abstract

Purpose: Many studies have established that inclement weather conditions are associated with elevated collision risk. Of particular concern are heavy precipitation events, which are overrepresented in crashes involving serious injury. As global climate changes in the coming decades, climate modellers project altered patterns of precipitation. The objectives of this study are twofold: to develop an approach for projecting the effects of climate change on traffic safety; and to evaluate the implications of changing rainfall patterns for road safety in Canadian cities. Method: Existing climatological records were integrated with the national collision database to establish present-day rainfall-related crash risk for two large urban areas in Canada – the Greater Toronto Area and Greater Vancouver. Global circulation models were used to establish scenarios of macro-climatic change. Downscaling methods were utilized to project localized changes in precipitation patterns for each city over the next 50 years. Baseline risk rates were then combined with projected future rain day frequencies in order to derive a first estimate of the possible effects of climate change on road safety in Canada. Results: Climate change projections show that southern Canada is likely to see an increase in total annual precipitation and altered seasonal precipitation patterns, with increased winter and spring precipitation and less summer precipitation. Greater frequency and variability of rainfall and extreme storm events are likely, with implications for driver adaptation and awareness of seasonal conditions. A slight to moderate increase in annual rainfall days is anticipated for Toronto, while Vancouver could see fewer rain days each year. Conclusion: Over the past 25 years, injury risk during rainfall has decreased significantly, but still remains highly elevated relative to dry conditions. Moving forward, it is likely that more frequent rain events in Toronto will result in a marginal increase in collision and casualty incidents over the next 50 years, while Vancouver could see a net safety benefit due to less frequent rainfall.

Derrick Hambly