Despite similar population densities, levels of urbanization, climates, and levels of economic development,road accidents across the province of Qu´ebec (and the rest of Canada) are twice ashigh as in Sweden, as measured by accident frequency and severity. Some of this disparity maybe explained by differences in road geometry, but some of this disparity is hypothesized to also beattributed to latent behavioural factors present in the general population.The objective of this research is to investigate latent differences in road user behaviour that mayexplain differences in accident history beyond any road safety effects derived from road design andtraffic composition. To that aim, a number of roundabouts in Qu´ebec and Sweden are selectedon the basis of similarity in design, for cross-sectional comparison. The modern roundabout ischosen as a case study as its implementation in North America is identical to that of Europe (wherethe design originated), and because roundabout operation relies heavily on road user behaviour(right-of-way is performed exclusively through rules of priority). This approach to intersectioncontrol is in stark contrast with typical stop-sign and traffic light control used throughout NorthAmerica. Analysis is performed using automated computer-vision-based trajectory extraction ofroad users from video data, coupled with surrogate safety methods to analyse behaviour andresulting safety proactively. Surrogate safety measures of interest for this study include speed andtime-to-collision, modelled using motion-pattern motion-prediction.Accident records recorded at the sample of roundabouts studied are found to be consistent withnational averages of each country respectively (twice as high and severe in Qu´ebec as in Sweden).After controlling for various geometric design features, land use, construction year, trafficexposure, and traffic patterns, an overall tendency of lower speeds and fewer serious conflicts (asmeasured by time-to-collision) are found at the Swedish roundabouts.These results are found to be consistent with local and national accident records, and would suggestthat some important latent regional factors-possibly related to educational or enforcement-are at play at the microscopic level. Further investigation of these regional factors is warranted infuture road safety studies.
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