The main objective of the project was to conceptually design a friction stir welding machine for joining rails. The applicability of friction stir welding types and its application in rail joining was investigated. A number of machine concepts for joining rail using friction stir welding techniques were developed and a final workable concept was laid out. In addition, the existing methods and machines for joining rails were considered, including arc welding, exothermic welding, flash butt welding and manual joining (rails joined by means of splice plate). After comparing different methods of joining rails, an optimized method was selected. The capabilities of the new conceptual machine, such as its ability to accommodate various rail profiles, were demonstrated through designs and various calculations. The development cost analysis was performed and a comparison was made with the other three methods of joining rails. Consequently, it was concluded that friction stir welding concept could be applied in rail joining and the costs associated with it could be lowered