Henok, Fikre (PhD)Fikadu, Mengistu2019-06-012023-11-042019-06-012023-11-042017-07http://etd.aau.edu.et/handle/123456789/18384One of the major problem in ballasted railroad is ballast flying and it should be studied and has to be minimized. Ballast flying is defined as the projection of ballast particles from its resting position as the train pass over the track structure. Ballast particles become airborne by overcoming gravity and friction (interlocking) forces from neighboring particles. The primary objectives of this paper are to identify the behavior of the railway ballast flying and to suggest possible solutions by assessing the ballast flying risk possibility (Addis – Adama project) and by determining the major causes of ballast flying in the project mentioned above mainly using discrete element modeling. Literatures have been thoroughly reviewed and the preliminary analysis were performed prior to the Discrete Element Method (DEM) analysis with a software Particle Flow Code (PFC). In this research modeling of the ballast material using PFC3D is done to get vibrational velocity of ballast used to construct from Addis to Adama project. The analysis is comprised of an impact load and ballast material behavior. Two types of gradation were used for the modeling and it shows different vibrational speed due to its mass. Finally conclusions were made based on the result. The result of the discrete element modeling (DEM) shows that ballast maximum vibrational speed is 0.014m/s. Addis – Adama is double truck and the summation of the speed of two trains at their passing point is about 250km/h. A train having 300km/h can lift ballast if vibrational speed is 0.02m/s. The ballast vibrational speed used for Addis – Adama is less than 0.02m/s and there is no ballast flight in the network. Even though there is no ballast flying some precautions have to be done.en-USBallast flyingDiscrete element modelingBallast vibrational speedBallast massThesis