Projected implications of climate change for rainfall-related collision risk

摘要

Purpose: Many studies have established that inclement weather conditions are associated withelevated collision risk. Of particular concern are heavy precipitation events, which areoverrepresented in crashes involving serious injury. As global climate changes in the comingdecades, climate modellers project altered patterns of precipitation. The objectives of this studyare 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 toestablish present-day rainfall-related crash risk for two large urban areas in Canada – theGreater Toronto Area and Greater Vancouver. Global circulation models were used to establishscenarios of macro-climatic change. Downscaling methods were utilized to project localizedchanges in precipitation patterns for each city over the next 50 years. Baseline risk rates werethen combined with projected future rain day frequencies in order to derive a first estimate of thepossible effects of climate change on road safety in Canada. Results: Climate changeprojections show that southern Canada is likely to see an increase in total annual precipitationand altered seasonal precipitation patterns, with increased winter and spring precipitation andless summer precipitation. Greater frequency and variability of rainfall and extreme stormevents 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 Vancouvercould see fewer rain days each year. Conclusion: Over the past 25 years, injury risk duringrainfall 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 marginalincrease in collision and casualty incidents over the next 50 years, while Vancouver could see anet safety benefit due to less frequent rainfall.