International Crash Experience Comparisons Using Prediction Models

Comparisons of crash frequencies are often done with a view to identifying how individual countries are performing relative to others in road safety experience. While such comparisons can be quite useful from a public health management perspective, they can be misleading to those who want a sense of how specific road safety initiatives are performing compared to similar ones in other countries. In particular, these comparisons will not allow engineers in one country to assess how well their designs for individual roadway elements are performing relative to the experience in other countries, or to the earlier experience in the same country. This paper has been prepared with two fundamental objectives in mind. Comparisons of selected crash prediction models from New Zealand, North America, Sweden, Italy and Australia are made to 1) illustrate how such comparisons might be used to learn lessons from differences in crash experience for similar roadway elements and 2) illustrate how to assess the transferability of these models among jurisdictions (countries or states). The results show that it is possible to transfer models from one jurisdiction to the next. However there are a number of differences between jurisdictions as a result of different reporting rates, design standards, speed limits and climate conditions that need to be accounted for when transferring models.