This research project investigated the relationship between roadside slope (embankment) characteristics and the severity of run-off-road crashes, with the aim of quantifying the safety risks associated with different batter slope configurations and demonstrating their relative safety benefits. The study reviewed national and international design practices, examined the influence of slope features on crash likelihood and severity, and assessed rollover risk. While slope and historical crash data were analysed, no significant relationship between crash risk and slope characteristics could be established due to limitations in the available slope data. During the project, the release of the updated 2020 Austroads Guide to Road Design Part 6 shifted the focus toward reviewing and updating Trauma Indices for roadside slopes, as existing severity indices were not supported by robust research. Although revised Trauma Indices were proposed, differences in fatal and serious injury rollover rates in Queensland highlighted the need for further locally based research before updates can be adopted. As a result, additional work is required to validate the proposed model and determine how the findings can be effectively implemented in practice.
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