Field investigation on the lateral resistance of ballasted tracks with strengthened steel sleepers using the multi sleeper push test

Lack of lateral resistance is one of the emerging problems in continuously welded rails. Lateral resistance is a type of resistance in which the railway track mobilizes against the applied lateral forces. Thus, curved tracks, especially sharp curves (curves with small radiuses), are the most susceptible segments for the lack of lateral resistance. The reason is, on curved tracks, in addition to the lateral forces applied by the train, longitudinal forces are decomposed into two parts, with one part being tangential (tangent to the curve) and the other part being radial. This radial force causes some defects to the track such as track buckling, transversal shifting of the track, pulling out of fastening shoulders, etc. Therefore, according to the general track instructions, welding of rails is not possible on curved tracks with a radius less than 400 m. With the help of laboratory tests, the authors of this paper previously showed that using two stiffeners under the steel sleeper increased the lateral resistance of the track adequately (by 140%) compared to the track with normal steel sleepers. In this paper, the effect of using two plate stiffeners under the steel sleepers was examined by field investigation on a real track. Two test methods, including the Single Tie (sleeper) Push Test (STPT) and the Multiple Tie (sleeper) Push Test (MTPT), were used to investigate the lateral resistance of the track. The results obtained by the STPT and MTPT methods showed an increase in lateral resistance by 139.6% and 135.5%, respectively. The obtained results are in accordance with the results of the laboratory tests. Moreover, the results showed that using two stiffeners under steel sleepers increased the lateral resistance of the track adequately, thereby enabling rails to be welded on curved tracks.