Landslide hazard and risk along the Unanderra to Moss Vale railway line

This paper concerns slope stability and the potential for landsliding along the Unanderra to Moss Vale Railway Line, in the state of New South Wales, Australia. Reference is made to different types (Type I Type II and Type III) of landslide hazard and risk assessment ranging from largely qualitative to significantly quantitative. These different types of hazard and risk assessment have been defined and discussed in earlier published works. In this paper quantitative assessments (Type III) are highlighted. The approach adopted is demonstrated with reference to a particular case study site along the railway route referred to earlier. Most landslides in the study area are triggered by rainfall. Therefore, analysis of rainfall, observational data and slope stability analyses are considered together to make coherent assessments of hazard. To facilitate realistic assessment of risk, it is necessary to consider the elements at risk and their vulnerability. In particular attention should be focussed on risk to human safety. There are always a number of uncertainties relating to subsurface data that arise mainly from limited site investigation. In many instances, the cost of more comprehensive investigations cannot be justified. In other cases, there may not be enough time to carry out further investigation. Calculated or assessed risk levels should be considered in relation to levels that may be acceptable or tolerable. Measures adopted as part of risk management can reduce existing risk levels significantly. An important challenge is to link risk assessment and risk management for economical, efficient and safe railway operations.