This report provides an understanding of the potential for Crash Risk Migration (CRM) to occur as a result of a range of road safety improvement treatments, focusing on situations where CRM may occur as a result of traffic redistribution. Existing research on CRM is methodologically flawed and inconclusive but it appears that CRM may occur due to traffic redistribution, and that the areas to which crash risk may migrate vary depending upon the treatment implemented. There is a need for local research to determine whether CRM is a real phenomenon or an artifact of reverse regression to the mean, and to identify the circumstances under which different treatments may produce CRM effects. However, an enormous investment would be required in order to fully understand CRM. Both the ARRB project team and Austroads representatives believe that such an investment is not warranted at present. At this stage it is recommended that the findings of this project can be used to inform practitioners of the issue of CRM and encourage their consideration of the potential impacts of engineering projects on crash risk at other sites. (Author/publisher)
Samenvatting