Field investigation on the effect of the tamping machine and dynamic track stabilizer on changing the rail support modulus

Due to increasing train speed and passage tonnage, the repair and maintenance of ballasted railway tracks is essential. As a result of cyclic train loads on ballasted tracks, the ballast layer can deteriorate. When the ballast bed deteriorates, it can change the track geometry, which leads to uncomfortable ride and an increase in wheel-rail interaction. Tamping is one of the most widely used methods for filling the ballast layer gaps around sleepers and homogenizing ballast beds in order to align the track geometry. After passing the tamping machine, the dynamic stabilizing machine is utilized to improve the quality of the ballast bed. The rail support modulus is an essential parameter for analyzing ballasted railway tracks, and it can change after maintenance operations. This paper extensively discusses the effects of maintenance operations on rail support modulus as an essential safety factor in ballasted tracks. In this study, a series of field tests are planned and conducted at Karaj station in Iran to investigate the effects of passing tamping and stabilizing machines on the rail support modulus in ballasted tracks. In this regard, the rail support modulus of the ballasted track according to deflection basins was measured in three stages (before tamping, after tamping, and after stabilizing), and the results were analyzed to determine the effects of passing maintenance machines on ballast beds. Based on the results, the tamping operation results in a 75.5% reduction in the rail support modulus, and after stabilizing the railway track, the rail support modulus is increased by 35.8%.