Welded rails have considerably improved the problems of wear and dynamic overloads that were the main causes of failure with mechanically joined rails. The weld material has been characterized by a series of tests performed at different temperatures for determining tensile properties and fracture toughness. Rails are welded together by utilizing flash butt welding to form one continuous rail that may be several kilometers long, or thermite welding to repair or splice together existing CWR segments. This form of track is very strong, gives a smooth ride and needs less maintenance. The trains can travel on it at higher speeds and with less friction. Welded rails are more expensive to lay than jointed tracks, but have much lower maintenance costs. The first welded track was used in Germany at 1924 and in US at 1930, and it has become common on main lines since the 1950s. There are two common types of rail welding: thermite rail welding and electric flash butt rail welding 3, 8, 9.