Mariamawit WoldeGabriel , Tewodros Gemechu
Several factors are considered when deciding upon the route alignment of a new railway line. Geohazards, such as landslides, are often ignored in this phase and are given attention in later advanced stages of the project. This tacit practice may result in unsafe and/or uneconomic designs and/or make the design process a futile task if careful evaluation results in a redo of the whole design. This paper makes the case for due consideration of geotechnical hazards from the very early stages of route selection. This is accomplished through quantifying landslide hazards associated with the ‘suggested’ alternative routes, carrying out appropriate analysis of geotechnical data, performing probabilistic slope stability analyses using various methods and quantifying the reliability of a system of landslide hazards along a certain route to select the better alternative. System failure probabilities for the two alternative alignments of the planned railway are evaluated with Event Trees and Minimal Cut Sets with the assumption that the initiating event of the ground water level rise had occurred and that failure events in the designated landslide zones are mutually independent. It has been showcased that the better alternative can be chosen based on probability of failure calculated using several reliability methods. The efficiency of the methods in determining component and system reliability parameters has also been discussed.