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The lateral resistance is one of the main functions of continuously welded rails that are influenced by various factors such as rail temperature, specifications of fastening systems, sleepers, ballast layer, the maintenance process of rails, etc. Nowadays, heavy haul and high-speed railways are operated under extremely complicated conditions, with the structure of the ballasted track and sleeper types also being constantly innovated. Therefore, research on the lateral resistance of ballasted tracks needs further investigation. In this paper, the ballasted track profile, the characteristics of the ballast aggregates, maintenance, and innovative sleepers were investigated and categorized to precisely examine the lateral behaviour of the ballasted tracks. In addition, the changes in the specifications of the abovementioned factors and components were also investigated. It was concluded that the geometry of the ballast layer and the interaction between the ballast and the sleeper are the main factors that led to the higher lateral resistance. In this regard, changes in the shape and type of sleepers as well as the ballast could increase the resistance. The influence of the loading frequency induced by trains and environmental conditions should be considered in further studies.

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The lateral displacement of sleepers is one of the key issues in railroads, which is caused by different factors such as the geometry of the ballast layer as well as the shape of the sleepers. Several methods have been proposed to improve the lateral resistance of sleepers on ballasted tracks. In this paper, a series of single tie push tests have been carried out to assess the performance of end-winged, middle-winged, and bumped sleepers on ballasted tracks with a variety of shoulder ballast widths and heights. Based on the experimental results, 500 mm and 150 mm were proposed as the optimum shoulder width and height, respectively. In addition, among the abovementioned sleepers, the EW_sleeper shows a significant increase in the total lateral resistance. Discrete element method (DEM) simulations were performed using PFC3D to determine the optimum size of the EW_sleeper wings. It was found that using a pair of wings measuring 14 cm in length and 13 cm in width can increase the lateral resistance compared to other alternatives.